p.6
Lipid Digestion and Absorption
What is the product of triglyceride digestion by pancreatic lipase?
Fatty acids and monoacylglycerides.
p.32
Nucleic Acid Digestion
How are the products of nucleic acid digestion absorbed?
Through the alimentary canal wall.
p.13
Absorption Mechanisms in the Small Intestine
How do water-soluble nutrients enter cells?
They use transport molecules embedded in the cell's plasma membrane.
p.6
Digestive Enzymes and Their Functions
What do nucleases target in the digestive process?
Ribonucleic acids and deoxyribonucleic acids.
p.28
Lipid Digestion and Absorption
What role do bile salts play in lipid absorption?
They speed up lipid digestion and are essential for absorbing the end products of lipid digestion.
p.25
Protein Digestion and Absorption
How are proteins absorbed in the small intestine?
Using an active transport mechanism, primarily in the duodenum and jejunum.
p.13
Absorption Mechanisms in the Small Intestine
What are lacteals?
Lymphatic capillaries in the small intestine that absorb dietary fats.
p.28
Lipid Digestion and Absorption
How do short-chain fatty acids enter the absorptive cells?
They are relatively water-soluble and can enter directly via simple diffusion.
p.1
Types of Digestion: Mechanical and Chemical
What is mechanical digestion?
A physical process where food is broken into smaller pieces without chemical change.
p.6
Digestive Enzymes and Their Functions
What is the function of trypsin in digestion?
To break down proteins into peptides.
p.18
Carbohydrate Digestion and Absorption
How is fructose absorbed and transported?
By facilitated diffusion alone.
p.19
Absorption Mechanisms in the Small Intestine
What is the function of glucose transporters (GLUTs)?
They enable glucose entrance and exit into cells.
p.34
Digestive Disorders and Malabsorption Issues
What is malabsorption?
A term used to characterize abnormalities of both digestion and absorption across the gastrointestinal tract.
p.33
Nucleic Acid Digestion and Absorption
What happens to the end products of nucleic acid digestion after they are absorbed?
They enter the bloodstream.
p.35
Digestive Disorders and Malabsorption Issues
What is lactose intolerance?
A digestive disorder caused by the inability to digest lactose due to a deficiency of lactase.
p.2
Types of Digestion: Mechanical and Chemical
Which substances in food must be chemically digested?
Carbohydrates, proteins, lipids, and nucleic acids.
p.38
Digestive Disorders and Malabsorption Issues
What are the treatment options for Irritable Bowel Syndrome?
Managing diet, lifestyle, and stress; in some cases, medication may be required.
p.5
Digestive Enzymes and Their Functions
What products result from the digestion of nucleotides?
Phosphates, nitrogenous bases, and pentoses.
p.38
Digestive Disorders and Malabsorption Issues
What is Crohn's disease?
A type of inflammatory bowel disease (IBD) that affects the large intestine.
p.39
Digestive Disorders and Malabsorption Issues
What amino acid absorption is primarily affected in Hartnup disease?
Nonpolar amino acids, specifically tryptophan.
p.10
Absorption Mechanisms in the Small Intestine
What is the primary goal of mechanical and chemical digestion?
To convert food into molecules small enough to be absorbed by epithelial cells of the intestinal villi.
p.3
Digestive Enzymes and Their Functions
Where are digestive enzymes secreted from?
Exocrine glands or the mucosal layer of epithelium lining the gastrointestinal tract.
p.21
Protein Digestion and Absorption
What is trypsinogen converted to?
Trypsin, its active form.
p.19
Absorption Mechanisms in the Small Intestine
Where is GLUT 2 predominantly found?
In the liver and pancreatic beta cells.
p.25
Protein Digestion and Absorption
What are dipeptides and tripeptides?
Short chains of two amino acids (dipeptides) or three amino acids (tripeptides) that are also transported actively.
p.1
Types of Digestion: Mechanical and Chemical
When does mechanical digestion begin?
With the first bite of food and continues as you chew.
p.23
Protein Digestion and Absorption
What is the function of rennin in milk digestion?
It coagulates milk to slow down its passage from the stomach.
p.2
Nucleic Acid Digestion and Absorption
What do nucleic acids break down into?
Nitrogen bases and sugars.
p.10
Absorption Mechanisms in the Small Intestine
What is absorption in the context of digestion?
The process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph.
p.33
Nucleic Acid Digestion and Absorption
How are the end products of nucleic acid digestion transported across the villus epithelium?
By carriers via active transport.
p.34
Digestive Disorders and Malabsorption Issues
What are some causes of abnormalities in digestion and absorption?
Enzyme deficiencies (like lactose intolerance), digestive failure (like bile acid/bile salt malabsorption), and infective agents.
p.34
Digestive Disorders and Malabsorption Issues
What are common symptoms of digestion and absorption abnormalities?
Bleeding, bloating, constipation, diarrhea, heartburn, incontinence, nausea, vomiting, stomach cramps, swallowing problems, weight loss or gain.
p.32
Nucleic Acid Digestion
Which intestinal brush border enzymes further break down nucleotides?
Nucleosidase and phosphatase.
p.37
Digestive Disorders and Malabsorption Issues
What is galactosemia?
An inherited condition in which galactose cannot be converted to glucose.
p.35
Digestive Disorders and Malabsorption Issues
What are some common symptoms of lactose intolerance?
Abdominal cramps, diarrhea, flatulence, bloating, nausea, vomiting, and occasionally constipation.
p.36
Digestive Disorders and Malabsorption Issues
What are some symptoms of GGM in newborns?
Diarrhea, dehydration, difficulties in weight gain, and glucosuria.
p.21
Protein Digestion and Absorption
What triggers the release of the hormone cholecystokinin in the duodenum?
The arrival of amino acids.
p.21
Protein Digestion and Absorption
What does cholecystokinin stimulate the secretion of?
Several pancreatic enzymes.
p.1
Absorption Mechanisms in the Small Intestine
What are the final products of digestion absorbed primarily?
From the digestive tract, primarily in the small intestine.
p.18
Carbohydrate Digestion and Absorption
What happens to monosaccharides after disaccharides are broken down?
They combine with transport proteins immediately.
p.2
Types of Digestion: Mechanical and Chemical
What is chemical digestion?
The biochemical process in which macromolecules in food are changed into smaller molecules that can be absorbed into body fluids.
p.14
Absorption Mechanisms in the Small Intestine
What is the absorption mechanism for glucose?
Co-transport with sodium ions.
p.25
Protein Digestion and Absorption
How do amino acids enter the capillary blood after absorption?
Via diffusion after being broken down from dipeptides and tripeptides.
p.30
Lipid Digestion and Absorption
Where do chylomicrons enter after being released from the cell?
The large pores of lacteals.
p.5
Digestive Enzymes and Their Functions
What does dipeptidase break down?
Dipeptides into amino acids.
What advantage do micelles provide during lipid digestion?
They increase surface area for lipase action and orient hydrophilic heads of fatty acids outward.
p.30
Lipid Digestion and Absorption
What happens to the breakdown products of triglycerides after passing through capillary walls?
They are used for energy by cells or stored in adipose tissue as fat.
p.9
Digestive Enzymes and Their Functions
What are the main functions of pancreatic enzymes?
To digest proteins, peptides, nucleic acids, and fats in the small intestine.
p.47
Metabolism: Catabolism and Anabolism
What happens during the reactions of the TCA cycle?
Release of ATP, NADH, and FADH2.
p.8
Lipid Digestion and Absorption
What are the products of emulsified triglycerides digestion by pancreatic lipase?
Fatty acids and monoacylglycerides.
p.48
Metabolism: Catabolism and Anabolism
What is the role of ATP in metabolism?
ATP serves as the energy currency of the cell.
p.88
Metabolism: Catabolism and Anabolism
What are the reactants involved in Reaction 7 of glycolysis?
2 ATP and phosphoglycerate.
p.76
Metabolism: Catabolism and Anabolism
What is the effect of elevated ATP levels on PFK-1?
ATP inhibits PFK-1 allosterically, indicating an abundance of high-energy compounds.
p.61
Metabolism: Catabolism and Anabolism
What is metabolism composed of?
The catabolism and anabolism of an organism.
p.76
Metabolism: Catabolism and Anabolism
What triggers the activation of PFK-1?
High concentrations of AMP activate PFK-1, signaling depleted energy stores.
p.6
Digestive Enzymes and Their Functions
What is the role of pancreatic elastase?
To break down proteins into peptides.
Where does digestion begin and end?
It begins in the mouth and ends in the small intestine.
p.23
Protein Digestion and Absorption
In what form is rennin present in the human body?
In its inactive form called prorennin.
p.1
Types of Digestion: Mechanical and Chemical
What are the two types of digestion in the digestive system?
Mechanical and chemical digestion.
p.38
Digestive Disorders and Malabsorption Issues
What is Irritable Bowel Syndrome (IBS)?
A condition involving irritation of the small intestine, leading to diarrhea or constipation.
p.30
Lipid Digestion and Absorption
Why can't chylomicrons pass through the basement membranes of blood capillaries?
Because of their large size.
p.29
Lipid Digestion and Absorption
What happens to free fatty acids and monoacylglycerides once inside epithelial cells?
They are reincorporated into triglycerides to form chylomicrons.
p.5
Digestive Enzymes and Their Functions
What type of enzymes are peptidases?
Brush border enzymes in the small intestine.
p.20
Protein Digestion and Absorption
What neutralizes the acidic chyme as it enters the small intestine?
Bile from the liver and bicarbonate from the pancreas.
p.20
Protein Digestion and Absorption
What happens to proteins in the stomach during digestion?
They are broken down into smaller polypeptides by HCl and pepsin.
p.42
Metabolism: Catabolism and Anabolism
What is metabolism?
Metabolism refers to the set of life-sustaining chemical reactions in organisms that convert food into energy.
p.44
Metabolism: Catabolism and Anabolism
What is the primary function of metabolism related to energy?
To obtain chemical energy from fuel molecules like carbohydrates, lipids, and proteins.
p.82
Overview of Digestion
What is the substrate for Reaction 4 in glycolysis?
Fructose 1,6-bisphosphate.
p.13
Absorption Mechanisms in the Small Intestine
How do lipid-soluble nutrients enter cells?
They can diffuse directly through the plasma membrane.
p.13
Absorption Mechanisms in the Small Intestine
What happens to lipid-soluble nutrients once inside the cell?
They are packaged for transport and enter the lacteals of the villi.
p.29
Lipid Digestion and Absorption
What is a micelle?
A tiny sphere with polar ends facing the watery environment and hydrophobic tails turned inward, enabling absorption of long-chain fatty acids.
p.25
Protein Digestion and Absorption
What is the role of sodium in the absorption of amino acids?
Most carriers for amino acids are linked to the active transport of sodium.
p.11
Absorption Mechanisms in the Small Intestine
What is the fourth mechanism of absorption?
Co-transport (or secondary active transport).
p.29
Lipid Digestion and Absorption
What is a chylomicron?
A water-soluble lipoprotein made of triglycerides, phospholipids, cholesterol, and surrounded by a protein coat.
p.19
Absorption Mechanisms in the Small Intestine
Where is GLUT 5 predominantly located and what does it transport?
In the small intestine, acting as a fructose transporter.
p.4
Digestive Enzymes and Their Functions
What are the products of Lingual lipase?
Free fatty acids, mono- and diglycerides.
p.39
Digestive Disorders and Malabsorption Issues
What type of disorder is Hartnup disease?
An autosomal recessive metabolic disorder.
p.15
Carbohydrate Digestion
What role does saliva play in carbohydrate digestion?
It lubricates food and provides alkaline conditions for amylase.
p.7
Digestive Enzymes and Their Functions
What end products are formed from the action of salivary amylase?
Disaccharides (maltose) and oligosaccharides.
p.35
Digestive Disorders and Malabsorption Issues
What is the treatment for lactose intolerance?
Removal of dairy products from the diet.
p.77
Digestive Enzymes and Their Functions
How does fructose 2,6-bisphosphate affect gluconeogenesis?
It inhibits fructose 1,6-bisphosphatase, an enzyme of gluconeogenesis.
p.65
Metabolism: Catabolism and Anabolism
What does the aerobic pathway of glycolysis lead to?
Oxidative decarboxylation of pyruvate to acetyl CoA.
p.65
Metabolism: Catabolism and Anabolism
What is the result of alcoholic fermentation pathway?
Pyruvate is converted to ethanol and carbon dioxide.
p.94
Metabolism: Catabolism and Anabolism
What is the role of pyruvate kinase (PK) in glycolysis?
It catalyzes the conversion of PEP to pyruvate, which is the third irreversible reaction of glycolysis.
p.81
Digestive Enzymes and Their Functions
What are the two products of the cleavage of fructose 1,6-bisphosphate?
Dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate.
p.12
Absorption Mechanisms in the Small Intestine
What is active transport?
Movement of a substance across a cell membrane from lower concentration to higher concentration.
p.13
Absorption Mechanisms in the Small Intestine
Where do water-soluble nutrients go after entering the capillary blood in the villi?
They travel to the liver via the hepatic portal vein.
p.33
Nucleic Acid Digestion and Absorption
What are the end products of nucleic acid digestion?
Pentose sugars, nitrogenous bases, and phosphate ions.
p.32
Nucleic Acid Digestion
What types of enzymes are involved in the digestion of dietary nucleic acids?
Pancreatic enzymes and enzymes produced by the small intestine.
p.21
Protein Digestion and Absorption
What do trypsin and chymotrypsin do to proteins?
They break down proteins into peptides.
p.6
Carbohydrate Digestion and Absorption
What types of carbohydrates does pancreatic amylase act on?
Polysaccharides (starches), producing α-Dextrins, disaccharides, and trisaccharides.
p.29
Lipid Digestion and Absorption
What additional substances do micelles contain?
Cholesterol and fat-soluble vitamins.
p.29
Lipid Digestion and Absorption
How do micelles facilitate lipid absorption?
They squeeze between microvilli and allow lipid substances to exit via simple diffusion.
p.29
Lipid Digestion and Absorption
What are the components that enter epithelial cells from micelles?
Free fatty acids and monoacylglycerides.
p.14
Absorption Mechanisms in the Small Intestine
Where do carbohydrates like glucose and galactose enter after absorption?
Capillary blood in villi.
p.15
Carbohydrate Digestion
Where does the chemical digestion of polysaccharides begin?
In the mouth, aided by amylase in saliva.
What role does bile play in lipid digestion?
Bile emulsifies large globules of food lipids into smaller ones called micelles.
p.9
Digestive Enzymes and Their Functions
What is the primary function of pepsin?
To break down proteins into peptides.
p.15
Carbohydrate Digestion
What happens to salivary α-amylase in the stomach?
It is inactivated by the low pH.
p.30
Lipid Digestion and Absorption
What are the breakdown products of triglycerides once processed?
Free fatty acids and glycerol.
p.42
Metabolism: Catabolism and Anabolism
What is anabolism?
The process of building up larger molecules from smaller ones, typically requiring energy.
p.43
Metabolism: Catabolism and Anabolism
What aspects are involved in metabolism?
Production, storage, and utilization of metabolic energy.
p.51
Overview of Digestion
What are some examples of compartments involved in inter-compartmental crossing?
Cellular compartments such as the cytoplasm, nucleus, and organelles like mitochondria.
p.8
Lipid Digestion and Absorption
What are the products of triglycerides digestion by lingual lipase?
Free fatty acids, and mono- and diglycerides.
p.48
Metabolism: Catabolism and Anabolism
What is anabolism?
The synthesis of all compounds needed by the cells.
p.60
Metabolism: Catabolism and Anabolism
What is metabolism?
The set of life-sustaining chemical reactions in organisms.
p.65
Metabolism: Catabolism and Anabolism
What happens to pyruvate in the anaerobic pathway?
It is reduced to lactate.
p.81
Digestive Enzymes and Their Functions
What does aldolase cleave in Reaction 4?
Fructose 1,6-bisphosphate.
p.54
Metabolism: Catabolism and Anabolism
What is the relationship between the product of one reaction and the substrate of the next in a metabolic pathway?
The product of one reaction serves as the substrate for the subsequent reaction.
p.78
Metabolism: Catabolism and Anabolism
How does ATP affect PFK-1 activity?
High levels of ATP inhibit PFK-1 activity, indicating sufficient energy levels in the cell.
p.66
Overview of Digestion
Where do the reactions of glycolysis occur in the cell?
In the cytosolic compartment.
p.3
Digestive Enzymes and Their Functions
What are enzymes?
Proteins that catalyze, or speed up, biochemical reactions.
p.12
Absorption Mechanisms in the Small Intestine
What is co-transport?
Movement of one molecule from higher to lower concentration powering the movement of another from lower to higher concentration.
p.18
Carbohydrate Digestion and Absorption
In what form are all carbohydrates absorbed?
As monosaccharides (Glucose, galactose, and fructose).
p.2
Types of Digestion: Mechanical and Chemical
What is the purpose of mechanical digestion?
To increase the surface area of food particles for more effective action by digestive enzymes.
p.20
Protein Digestion and Absorption
What must proteins be broken down into before absorption?
Their constituent amino acids.
What are the most common dietary lipids?
Triglycerides, made up of a glycerol molecule and three fatty acid chains.
p.30
Lipid Digestion and Absorption
What are chylomicrons and where are they processed?
Chylomicrons are lipoproteins processed by the Golgi apparatus.
p.15
Carbohydrate Digestion
What process reduces the length of polysaccharides during digestion?
The breaking of bonds between glucose monomers.
p.36
Digestive Disorders and Malabsorption Issues
What symptoms can adults experience with GGM?
Bloating, nausea, diarrhea, abdominal cramps, and frequent urination.
p.14
Absorption Mechanisms in the Small Intestine
What is the absorption mechanism for amino acids?
Co-transport with sodium ions.
p.37
Digestive Disorders and Malabsorption Issues
What long-term problems can occur despite treatment for Classic galactosemia?
Intellectual deficits, movement disorders, and premature ovarian failure (in females).
p.17
Digestive Enzymes and Their Functions
What substrates does salivary amylase act on?
Polysaccharides (starch).
p.8
Lipid Digestion and Absorption
What are the products of triglyceride digestion by gastric lipase?
Fatty acids and monoacylglycerides.
p.45
Metabolism: Catabolism and Anabolism
What is the primary function of anabolic reactions?
To consume energy to build complex molecules.
p.49
Metabolism: Catabolism and Anabolism
What is the primary function of anabolism?
To build up large molecules from smaller ones.
p.10
Absorption Mechanisms in the Small Intestine
Where in the small intestine are the end products of digestion primarily absorbed?
In the jejunum and ileum regions.
p.12
Absorption Mechanisms in the Small Intestine
What characterizes facilitated diffusion?
Movement of substances from higher to lower concentration using a carrier protein in the cell membrane.
p.3
Digestive Enzymes and Their Functions
What part of the digestive system secretes enzymes besides the mouth?
The stomach lining and the small intestine lining.
p.12
Absorption Mechanisms in the Small Intestine
What is endocytosis?
A transportation process where the cell membrane engulfs material, requiring energy, usually in the form of ATP.
p.25
Protein Digestion and Absorption
What happens to dipeptides and tripeptides once inside absorptive epithelial cells?
They are broken down into their amino acids before leaving the cell.
p.20
Protein Digestion and Absorption
What does Gastrin stimulate the secretion of?
HCl by parietal cells and pepsinogen by chief cells.
p.26
Digestive Enzymes and Their Functions
What are the three lipases responsible for lipid digestion?
Lingual lipase, gastric lipase, and pancreatic lipase.
p.7
Digestive Enzymes and Their Functions
What substrate does salivary amylase act on?
Polysaccharides (Starch).
p.39
Digestive Disorders and Malabsorption Issues
How is steatorrhea treated?
By correcting the underlying cause and using digestive enzyme supplements.
p.17
Digestive Enzymes and Their Functions
What are the end products of salivary amylase activity?
Disaccharides (maltose) and oligosaccharides.
p.43
Metabolism: Catabolism and Anabolism
What role do enzymes play in metabolism?
Enzymes catalyze the chemical reactions, being highly specific and regulated.
p.47
Metabolism: Catabolism and Anabolism
What occurs in the second stage of catabolism?
Degradation of monomers to Acetyl-CoA.
p.17
Digestive Enzymes and Their Functions
Where do oligosaccharidases act in the digestive system?
In the small intestine at the brush border membrane.
p.48
Metabolism: Catabolism and Anabolism
What are the two main phases of metabolism?
Catabolism and Anabolism.
p.65
Metabolism: Catabolism and Anabolism
What are the two main pathways glycolysis can lead to under different conditions?
Aerobic and anaerobic pathways.
p.74
Metabolism: Catabolism and Anabolism
What role does glucose-6-phosphate play in cellular metabolism?
It serves as a substrate for glycolysis and the pentose phosphate pathway.
p.66
Overview of Digestion
What are the two main phases of glycolysis?
Energy-investment phase and energy-generation phase.
p.75
Metabolism: Catabolism and Anabolism
What significant role does PFK-1 play in glycolysis?
It is the most important control point and the rate-limiting step.
p.53
Metabolism: Catabolism and Anabolism
What characterizes the fed state in metabolic conditions?
Increased energy storage.
p.91
Metabolism: Catabolism and Anabolism
How does the Rapoport-Luebering shunt affect hemoglobin's affinity for oxygen?
By increasing 2,3-BPG levels, it decreases hemoglobin's affinity for oxygen, facilitating oxygen delivery to tissues.
p.85
Metabolism: Catabolism and Anabolism
What is produced during the oxidation of Glyceraldehyde 3-phosphate?
NADH and 1,3-bisphosphoglycerate.
p.85
Metabolism: Catabolism and Anabolism
What enzyme catalyzes the oxidation of Glyceraldehyde 3-phosphate?
Glyceraldehyde 3-phosphate dehydrogenase.
p.12
Absorption Mechanisms in the Small Intestine
What is passive diffusion?
The movement of substances from an area of higher concentration to an area of lower concentration.
p.18
Carbohydrate Digestion and Absorption
How are glucose and galactose transported into epithelial cells?
By common protein carriers via secondary active transport with sodium ions.
p.32
Nucleic Acid Digestion
What are the end products of nucleic acid digestion in the small intestine?
Pentoses, phosphates, and nitrogenous bases.
p.19
Absorption Mechanisms in the Small Intestine
What role does GLUT 4 play in the body?
It transports glucose into muscles and fat cells.
p.28
Lipid Digestion and Absorption
How do bile salts and lecithin assist in the absorption of long-chain fatty acids?
They enclose them in a micelle.
p.5
Digestive Enzymes and Their Functions
What enzymes are involved in the breakdown of nucleotides?
Nucleosidases and phosphatases.
p.38
Digestive Disorders and Malabsorption Issues
What are the symptoms of Crohn's disease?
Abdominal pain, severe diarrhea, fatigue, weight loss, and malnutrition.
p.39
Digestive Disorders and Malabsorption Issues
What does steatorrhea indicate?
A disorder of lipid absorption.
p.7
Digestive Enzymes and Their Functions
What are the end products of pancreatic amylase?
Disaccharides (maltose) and monosaccharides.
p.45
Metabolism: Catabolism and Anabolism
What is anabolism?
Synthetic reactions that build up molecules.
p.45
Metabolism: Catabolism and Anabolism
What is the primary function of catabolic reactions?
To release energy by breaking down complex molecules.
p.47
Metabolism: Catabolism and Anabolism
What is the final stage in catabolism?
ATP formation in the electron transport chain.
p.48
Metabolism: Catabolism and Anabolism
What is catabolism?
The breakdown of molecules to obtain energy.
p.88
Metabolism: Catabolism and Anabolism
What is produced in Reaction 7 of glycolysis?
Phosphoglycerate synthesis.
p.77
Metabolism: Catabolism and Anabolism
What mechanism does fructose 2,6-bisphosphate employ to prevent futile cycles?
It activates glycolysis while inhibiting gluconeogenesis, ensuring both pathways are not fully active at the same time.
p.74
Carbohydrate Digestion and Absorption
What is glucose-6-phosphate?
A phosphorylated form of glucose that plays a key role in carbohydrate metabolism.
p.75
Metabolism: Catabolism and Anabolism
What is the product of the phosphorylation of fructose 6-phosphate?
Fructose 1,6-bisphosphate.
p.70
Digestive Enzymes and Their Functions
Which anomers of glucose can these isozymes act upon?
Both the α- and β-anomers of glucose.
p.60
Metabolism: Catabolism and Anabolism
What is anabolism?
The process of synthesizing larger molecules from smaller units.
p.73
Metabolism: Catabolism and Anabolism
Is the reaction of glucose 6-phosphate to fructose 6-phosphate reversible?
Yes, the reaction is readily reversible.
p.75
Metabolism: Catabolism and Anabolism
How many ATP molecules are consumed during the reaction catalyzed by PFK-1?
Two ATP molecules are consumed.
p.6
Digestive Enzymes and Their Functions
Where are pancreatic enzymes produced?
In the pancreatic acinar cells.
p.34
Digestive Disorders and Malabsorption Issues
What can malabsorption lead to?
Malnutrition and a variety of anaemias.
p.4
Digestive Enzymes and Their Functions
What is the product of Gastric lipase?
Fatty acids and monoacylglycerides.
p.23
Protein Digestion and Absorption
What activates prorennin to produce active rennin?
Hydrochloric acid produced in the stomach.
p.28
Lipid Digestion and Absorption
What pathway do short-chain fatty acids take after absorption?
They enter the blood capillary of a villus, similar to monosaccharides and amino acids.
p.36
Digestive Disorders and Malabsorption Issues
What is Glucose-Galactose Malabsorption (GGM)?
An inherited metabolic disorder causing inability to absorb glucose and galactose.
p.28
Lipid Digestion and Absorption
Why can't long-chain fatty acids and glycerol be absorbed directly?
Because they are insoluble in water.
p.36
Digestive Disorders and Malabsorption Issues
What causes GGM?
A mutation in the gene responsible for the sodium/glucose cotransport protein I (SGLT1).
p.38
Digestive Disorders and Malabsorption Issues
What are common symptoms of Irritable Bowel Syndrome?
Abdominal pain, unpredictable bowel movements, variation in stool consistency, bloating, flatulence, nausea, headache, fatigue, depression, anxiety, and difficulty concentrating.
p.14
Absorption Mechanisms in the Small Intestine
What is the destination for absorbed carbohydrates?
Liver via hepatic portal vein.
p.35
Digestive Disorders and Malabsorption Issues
What are the two main types of lactose intolerance?
Primary and secondary lactose intolerance.
p.37
Digestive Disorders and Malabsorption Issues
What enzyme is completely deficient in Classic galactosemia (Type 1)?
Galactose-1-phosphate uridyl transferase (GALT).
p.38
Digestive Disorders and Malabsorption Issues
What medications are used to manage Crohn's disease?
Steroids and immunosuppressants are used to slow disease progression.
p.42
Metabolism: Catabolism and Anabolism
What are the two main types of metabolism?
Catabolism and Anabolism.
p.47
Metabolism: Catabolism and Anabolism
What is the first stage of catabolism?
Hydrolysis of macromolecules to building blocks, such as polysaccharides to glucose and proteins to amino acids.
p.17
Digestive Enzymes and Their Functions
What are the end products of pancreatic amylase?
Disaccharides (maltose) and monosaccharides.
p.50
Metabolism: Catabolism and Anabolism
What metabolic process occurs in the nucleus?
DNA replication and transcription.
p.52
Metabolism: Catabolism and Anabolism
Where does metabolism primarily occur in the body?
In tissues and organs such as the blood, liver, muscle, adipose tissue, brain, kidney, and adrenals.
p.52
Metabolism: Catabolism and Anabolism
What role does the brain have in metabolism?
The brain is also involved in metabolic processes.
p.55
Metabolism: Catabolism and Anabolism
What does a reaction pathway illustrate?
The sequence of steps in a chemical reaction.
p.70
Digestive Enzymes and Their Functions
How do these isozymes respond to conditions like diabetes or insulin?
They are non-inducible enzymes and are not affected by diabetes or insulin.
p.78
Metabolism: Catabolism and Anabolism
What are the main allosteric regulators of PFK-1?
Citrate (inhibitor) and AMP (activator).
p.73
Metabolism: Catabolism and Anabolism
Is the isomerization of glucose 6-phosphate a rate-limiting step?
No, it is not a rate-limiting or regulated step.
p.59
Metabolic Disorders and Malabsorption Issues
What is G6PD deficiency?
A metabolic disease caused by a genetic enzyme deficiency.
p.71
Digestive Enzymes and Their Functions
What role does glucokinase play in hypothalamic neurons?
It serves as a glucose sensor, key in the adrenergic response to hypoglycemia.
p.21
Protein Digestion and Absorption
What enzymes do the cells of the brush border secrete to further break down peptides?
Aminopeptidase and dipeptidase.
p.13
Absorption Mechanisms in the Small Intestine
What does the absorption of most nutrients through the intestinal villi require?
Active transport fueled by ATP.
p.21
Protein Digestion and Absorption
What is the final result of protein digestion in the small intestine?
Molecules small enough to enter the bloodstream.
p.16
Carbohydrate Digestion and Absorption
What are the simple sugars produced from carbohydrate digestion?
Glucose, fructose, and galactose.
p.15
Carbohydrate Digestion
What is the main component of dietary carbohydrates?
The plant polysaccharide amylose and animal polysaccharide glycogen.
p.34
Digestive Disorders and Malabsorption Issues
What factors can impair the absorption of nutrients?
Single or multiple nutrient abnormalities depending on the condition.
p.4
Digestive Enzymes and Their Functions
What role does Enteropeptidase serve in digestion?
It activates Trypsinogen to Trypsin.
p.20
Digestive Enzymes and Their Functions
What are the three primary enzymes involved in protein digestion?
Pepsin, trypsin, and chymotrypsin.
p.2
Lipid Digestion and Absorption
What are lipids broken down into?
Fatty acids and glycerol.
p.39
Digestive Disorders and Malabsorption Issues
What are some symptoms of Hartnup disease?
Failure to thrive, photosensitivity, intermittent ataxia, nystagmus, and tremor.
p.37
Digestive Disorders and Malabsorption Issues
What is characteristic of Galactokinase deficiency (Type 2)?
A deficiency of the enzyme galactokinase 1, typically causing only cataracts.
p.9
Digestive Enzymes and Their Functions
What are brush border enzymes?
Enzymes present in the small intestine that break down peptides and nucleotides.
p.45
Metabolism: Catabolism and Anabolism
What is catabolism?
Degradative reactions that break down molecules.
p.44
Metabolism: Catabolism and Anabolism
What macromolecules are assembled from building blocks in metabolism?
Carbohydrates, proteins, lipids, nucleic acids, and other cell components.
p.61
Metabolism: Catabolism and Anabolism
In which living things does metabolism occur?
In bacteria, plants, animals, and humans.
p.55
Metabolism: Catabolism and Anabolism
What are the key components of a reaction pathway?
Reactants, intermediates, and products.
p.85
Metabolism: Catabolism and Anabolism
What is Glyceraldehyde 3-phosphate (G3P)?
A three-carbon sugar involved in glycolysis and the Calvin cycle.
p.71
Digestive Enzymes and Their Functions
What is the primary function of glucokinase in β cells?
To act as a glucose sensor and determine the threshold for insulin secretion.
p.83
Digestive Enzymes and Their Functions
What does triose phosphate isomerase do?
It interconverts dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate.
p.92
Metabolism: Catabolism and Anabolism
What role does 3-Phosphoglycerate play in the Calvin cycle?
It is formed from ribulose bisphosphate and carbon dioxide.
p.67
Carbohydrate Digestion and Absorption
Which enzymes catalyze the phosphorylation of glucose?
Hexokinase or glucokinase.
p.67
Carbohydrate Digestion and Absorption
Why do phosphorylated sugar molecules not readily penetrate cell membranes?
There are no specific transmembrane carriers, and they are too polar to diffuse through the lipid bilayer.
p.18
Carbohydrate Digestion and Absorption
How do monosaccharides leave epithelial cells?
Via facilitated diffusion and then enter capillaries through intercellular clefts.
p.2
Types of Digestion: Mechanical and Chemical
Where does most chemical digestion occur?
In the first part of the small intestine (duodenum).
p.14
Lipid Digestion and Absorption
How do long-chain fatty acids enter intestinal cells?
Diffusion, combined with proteins to create chylomicrons.
p.22
Digestive Enzymes and Their Functions
What are the end products of carboxypeptidase's action?
Amino acids and peptides.
p.7
Digestive Enzymes and Their Functions
What does pancreatic amylase act on?
Polysaccharides (Starch).
p.9
Digestive Enzymes and Their Functions
What does aminopeptidase primarily act on?
Amino acids at the amino end of peptides.
p.9
Digestive Enzymes and Their Functions
What does chymotrypsin do?
Breaks down proteins and peptides in the small intestine.
p.9
Digestive Enzymes and Their Functions
What do ribonuclease and deoxyribonuclease target?
Ribonucleic acids and deoxyribonucleic acids, respectively.
p.17
Digestive Enzymes and Their Functions
What are the monosaccharides produced by oligosaccharidases?
Glucose, fructose, and galactose.
p.77
Digestive Enzymes and Their Functions
What is the role of fructose 2,6-bisphosphate in glycolysis?
It is the most potent activator of PFK-1.
p.58
Metabolism: Catabolism and Anabolism
How does the metabolic status affect metabolic regulation?
It distinguishes between fed or starved states, influencing metabolism control.
p.54
Metabolism: Catabolism and Anabolism
What is a metabolic pathway?
A sequence of chemical reactions occurring within a cell.
p.75
Digestive Enzymes and Their Functions
Which enzyme phosphorylates fructose 6-phosphate?
Phosphofructokinase-1 (PFK-1).
p.74
Metabolism: Catabolism and Anabolism
What are the main pathways that utilize glucose-6-phosphate?
Glycolysis and the pentose phosphate pathway.
p.66
Metabolism: Catabolism and Anabolism
What occurs during the energy-investment phase of glycolysis?
Phosphorylated forms of intermediates are synthesized at the expense of ATP.
p.56
Metabolism: Catabolism and Anabolism
How many ATP molecules are produced in the glycolytic pathway per glucose molecule?
A net gain of 2 ATP molecules.
p.54
Metabolism: Catabolism and Anabolism
Can reaction steps in a metabolic pathway be reversible?
Yes, a reaction step may be reversible or irreversible.
p.83
Metabolism: Catabolism and Anabolism
Why must dihydroxyacetone phosphate (DHAP) be isomerized?
It must be isomerized to glyceraldehyde 3-phosphate for further metabolism by the glycolytic pathway.
p.69
Digestive Enzymes and Their Functions
What does a low Km indicate for hexokinase?
A high affinity for glucose.
p.79
Metabolism: Catabolism and Anabolism
What causes PFK-2 to be active in the well-fed state?
Dephosphorylation of PFK-2 due to increased fructose 2,6-bisphosphate.
p.72
Metabolism: Catabolism and Anabolism
How does glucokinase help minimize hyperglycemia during the absorptive period?
By preventing large amounts of glucose from entering the systemic circulation after a meal.
p.86
Metabolism: Catabolism and Anabolism
What is linked to carbon 1 of the 1,3-BPG product?
A phosphate group by a high-energy bond.
p.36
Digestive Disorders and Malabsorption Issues
What is the role of SGLT1 in glucose and galactose absorption?
It carries both sugars into the intestines.
p.23
Protein Digestion and Absorption
What role does calcium play in the milk digestion process?
It helps rennin change casein into paracasein and forms calcium paracaseinate.
What does pancreatic lipase do to triglycerides?
It breaks them down into two free fatty acids and a monoglyceride.
What types of fatty acids are included in lipid digestion?
Both short-chain (less than 10 to 12 carbons) and long-chain fatty acids.
p.39
Digestive Disorders and Malabsorption Issues
What causes steatorrhea?
A deficit in bile secretion or pancreatic juice into the intestine.
p.39
Digestive Disorders and Malabsorption Issues
What is the manifestation of steatorrhea?
Presence of excess fats in feces.
p.46
Metabolism: Catabolism and Anabolism
What is amphibolism?
It involves reaction processes that include both synthesis and breakdown of molecules.
p.50
Metabolism: Catabolism and Anabolism
What is the role of the endoplasmic reticulum in metabolism?
It is involved in the synthesis of lipids and proteins.
p.48
Metabolism: Catabolism and Anabolism
How do catabolism and anabolism interact?
Catabolism provides the energy and building blocks for anabolic processes.
p.60
Metabolism: Catabolism and Anabolism
What are the two main types of metabolism?
Catabolism and Anabolism.
p.60
Metabolism: Catabolism and Anabolism
What is catabolism?
The process of breaking down molecules to obtain energy.
p.82
Carbohydrate Digestion and Absorption
What are the products of the cleavage of Fructose 1,6-bisphosphate?
Dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P).
p.65
Metabolism: Catabolism and Anabolism
Which organisms primarily utilize the alcoholic fermentation pathway?
Mainly prokaryotes, such as yeast and some strains of bacteria.
p.94
Metabolism: Catabolism and Anabolism
What type of phosphorylation occurs during the conversion of PEP to pyruvate?
Substrate-level phosphorylation.
p.55
Metabolism: Catabolism and Anabolism
What is the significance of activation energy in a reaction pathway?
It is the energy required to initiate a chemical reaction.
p.64
Metabolism: Catabolism and Anabolism
Is glycolysis used by all tissues?
Yes, all tissues use glycolysis for glucose oxidation.
p.71
Digestive Enzymes and Their Functions
How does glucokinase differ from other hexokinases regarding inhibition?
Glucokinase activity is not directly inhibited by glucose 6-phosphate.
p.85
Metabolism: Catabolism and Anabolism
What is the role of NAD+ in the oxidation of Glyceraldehyde 3-phosphate?
It acts as an electron carrier, being reduced to NADH.
p.79
Metabolism: Catabolism and Anabolism
What is the effect of low fructose 2,6-bisphosphate during fasting?
It inhibits glycolysis and activates gluconeogenesis.
p.87
Metabolism: Catabolism and Anabolism
How is the reaction catalyzed by phosphoglycerate kinase unique?
It is physiologically reversible, unlike most other kinases.
p.63
Metabolism: Catabolism and Anabolism
What happens to pyruvate after glycolysis under aerobic conditions?
It enters the mitochondria for further oxidation in the citric acid cycle.
p.72
Metabolism: Catabolism and Anabolism
What is the specificity of glucokinase?
Glucokinase has absolute specificity for glucose.
p.86
Metabolism: Catabolism and Anabolism
What role does the high-energy phosphate play in glycolysis?
It drives ATP synthesis in the next reaction.
p.86
Digestive Disorders and Malabsorption Issues
What additional effect does arsenate have besides harming glycolysis?
It inhibits ATP synthase in the electron transport chain (ETC).
p.35
Digestive Disorders and Malabsorption Issues
What causes primary lactose intolerance?
A decrease in lactase production with age.
p.37
Digestive Disorders and Malabsorption Issues
What are early signs and symptoms of Classic galactosemia?
Liver dysfunction, susceptibility to infections, failure to thrive, and cataracts.
p.35
Digestive Disorders and Malabsorption Issues
What causes secondary lactose intolerance?
Illnesses such as a stomach bug or celiac disease, leading to inflammation in the gut wall.
p.5
Digestive Enzymes and Their Functions
What does carboxypeptidase do?
Breaks down amino acids at the carboxyl end of peptides.
p.5
Digestive Enzymes and Their Functions
What is chymotrypsin's role in digestion?
Breaks down proteins into peptides.
p.14
Nucleic Acid Digestion and Absorption
How are nucleic acid digestion products absorbed?
Active transport via membrane carriers.
p.43
Metabolism: Catabolism and Anabolism
What does the term 'metabolism' mean?
It comes from the Greek word 'metabole,' which means change.
p.43
Metabolism: Catabolism and Anabolism
What does metabolism comprise?
All the chemical reactions that take place in a living system.
p.44
Metabolism: Catabolism and Anabolism
What do metabolic processes convert exogenous nutrients into?
Building blocks or precursors of macromolecular cell components.
p.44
Metabolism: Catabolism and Anabolism
What roles do metabolic processes play in relation to biomolecules?
They form and degrade biomolecules required for specialized functions in cells.
p.49
Metabolism: Catabolism and Anabolism
What is the primary function of catabolism?
To break down large molecules to form smaller ones.
p.36
Digestive Disorders and Malabsorption Issues
How is GGM treated?
By avoiding milk, milk products, and foods containing glucose and galactose.
p.14
Lipid Digestion and Absorption
Where do long-chain fatty acids go after absorption?
Lacteals of villi to systemic circulation via lymph entering thoracic duct.
p.37
Digestive Disorders and Malabsorption Issues
What enzyme deficiency causes Galactose epimerase deficiency (Type 3)?
UDP-galactose-4-epimerase.
p.7
Digestive Enzymes and Their Functions
What are the end products of the brush border enzymes?
Monosaccharides (e.g., glucose, fructose, galactose).
p.42
Metabolism: Catabolism and Anabolism
What is catabolism?
The process of breaking down molecules to obtain energy.
p.17
Digestive Enzymes and Their Functions
What substrates does pancreatic amylase act on?
Polysaccharides (starch).
p.51
Metabolism: Catabolism and Anabolism
Why is inter-compartmental crossing important?
It allows for the exchange of nutrients and waste products between compartments, supporting various metabolic processes.
p.47
Metabolism: Catabolism and Anabolism
What is the nature of catabolism?
Catabolism is convergent in nature.
p.58
Metabolism: Catabolism and Anabolism
What are the main factors that regulate metabolic pathways?
Enzymes, hormones, compartmentalization, specialized products, and metabolic status.
p.76
Metabolism: Catabolism and Anabolism
How does citrate affect PFK-1 activity?
Citrate inhibits PFK-1, favoring glucose use for glycogen synthesis.
p.73
Digestive Enzymes and Their Functions
What enzyme catalyzes the isomerization of glucose 6-phosphate?
Phosphohexoseisomerase (phosphoglucoseisomerase).
p.64
Metabolism: Catabolism and Anabolism
What is the primary purpose of the glycolytic pathway (EMP pathway)?
To oxidize glucose to provide energy (as ATP) and intermediates for other metabolic pathways.
p.61
Metabolism: Catabolism and Anabolism
When does metabolism begin and end in an organism?
It starts at conception and stops at death.
p.71
Digestive Enzymes and Their Functions
Where is glucokinase predominantly found?
In liver parenchymal cells and pancreatic β cells.
p.53
Metabolism: Catabolism and Anabolism
What is the main challenge during the diseased state?
Metabolic struggle for survival.
p.69
Digestive Enzymes and Their Functions
What important regulatory role does hexokinase play?
It is a regulatory enzyme of glycolysis, inhibited by glucose-6-phosphate.
p.63
Metabolism: Catabolism and Anabolism
What are the two phases of glycolysis?
The energy investment phase and the energy payoff phase.
p.72
Metabolism: Catabolism and Anabolism
What effect does glucokinase's high Vmax have on glucose metabolism?
It allows the liver to effectively remove the flood of glucose delivered by the portal blood.
p.80
Regulation of Glycolysis
What activates PFK-1 in the liver?
Fructose-2,6-bisphosphate (F-2,6-bisP).
p.84
Digestive Enzymes and Their Functions
Why must NADH be oxidized back to NAD+?
To allow glycolysis to continue due to limited NAD+ in the cell.
p.15
Carbohydrate Digestion
What does the brush border enzyme α-dextrinase do?
It breaks off one glucose unit at a time from α-dextrin.
p.14
Lipid Digestion and Absorption
How are monoacylglycerides absorbed?
Diffusion into intestinal cells, combined with proteins to create chylomicrons.
p.9
Digestive Enzymes and Their Functions
What is the function of dipeptidase?
To break down dipeptides into amino acids.
p.9
Digestive Enzymes and Their Functions
What are nucleosidase and phosphatase responsible for?
Breaking down nucleotides into phosphates, nitrogenous bases, and pentoses.
p.51
Absorption Mechanisms in the Small Intestine
What does inter-compartmental crossing refer to?
The process of substances moving between different compartments in a biological system.
p.51
Absorption Mechanisms in the Small Intestine
How is inter-compartmental crossing regulated?
Through specific transport proteins and channels that facilitate the movement of molecules across compartment membranes.
p.70
Digestive Enzymes and Their Functions
What is the characteristic of these isozymes regarding maximal velocity (Vmax) for glucose?
They have a low maximal velocity (Vmax) for glucose, limiting glucose phosphorylation to what the cell can use.
p.82
Carbohydrate Digestion and Absorption
What occurs during the cleavage of Fructose 1,6-bisphosphate?
It is split into two three-carbon molecules: dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (G3P).
p.56
Metabolism: Catabolism and Anabolism
What is the main function of the glycolytic pathway?
To convert glucose into pyruvate, producing energy.
p.66
Overview of Digestion
What is the overall process of glycolysis?
The conversion of glucose to pyruvate in two stages.
p.78
Metabolism: Catabolism and Anabolism
What role does PFK-1 play in glycolysis?
It is a key regulatory enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.
p.92
Metabolism: Catabolism and Anabolism
What is the significance of 3-Phosphoglycerate in metabolic reactions?
It serves as an intermediate in glycolysis and the Calvin cycle.
p.55
Digestive Enzymes and Their Functions
What role do enzymes play in reaction pathways?
Enzymes act as catalysts, speeding up the reaction steps.
p.60
Metabolism: Catabolism and Anabolism
Why is metabolism important?
It provides energy for vital processes and helps in the growth and repair of tissues.
p.66
Metabolism: Catabolism and Anabolism
What happens during the energy-generation phase of glycolysis?
A net of two molecules of ATP are formed by substrate-level phosphorylation per glucose molecule metabolized.
p.53
Metabolism: Catabolism and Anabolism
What happens during the starved state?
Increased energy release.
p.75
Metabolism: Catabolism and Anabolism
What is formed from fructose 6-phosphate by phosphofructokinase-2 (PFK-2)?
Fructose 2,6-bisphosphate.
p.69
Digestive Enzymes and Their Functions
Where is hexokinase found?
In all cells/tissues (ubiquitous).
p.91
Metabolism: Catabolism and Anabolism
In which pathway does the Rapoport-Luebering shunt operate?
It operates within the glycolytic pathway.
p.81
Digestive Enzymes and Their Functions
What does Aldolase B do in addition to cleaving fructose 1,6-bisphosphate?
It also cleaves fructose 1-phosphate and functions in dietary fructose metabolism.
p.91
Metabolism: Catabolism and Anabolism
What is the significance of 2,3-bisphosphoglycerate (2,3-BPG) in RBCs?
It plays a crucial role in modulating oxygen release from hemoglobin.
p.83
Metabolism: Catabolism and Anabolism
What is the net production of glyceraldehyde 3-phosphate from the cleavage products of fructose 1,6-bisphosphate?
Two molecules of glyceraldehyde 3-phosphate.
p.70
Digestive Enzymes and Their Functions
What does the broad substrate specificity of these isozymes mean?
They can phosphorylate several hexoses, such as fructose, mannose, and galactose, though at a slower rate.
p.74
Carbohydrate Digestion and Absorption
How is glucose-6-phosphate formed?
By the phosphorylation of glucose, catalyzed by the enzyme hexokinase.
p.64
Metabolism: Catabolism and Anabolism
What are the end products of glycolysis?
Pyruvate, energy (ATP), and NADH.
p.92
Metabolism: Catabolism and Anabolism
What reactions are associated with 3-Phosphoglycerate?
Reactions 8, 9, and 10 in the glycolytic pathway.
p.60
Metabolism: Catabolism and Anabolism
What role do enzymes play in metabolism?
They act as catalysts to speed up chemical reactions.
p.55
Digestive Disorders and Malabsorption Issues
How can a reaction pathway be affected by inhibitors?
Inhibitors can slow down or halt the reaction by affecting enzyme activity.
p.79
Metabolism: Catabolism and Anabolism
What happens to fructose 2,6-bisphosphate during fasting?
It decreases due to elevated glucagon and low insulin levels.
p.80
Regulation of Glycolysis
Which enzyme is considered the major regulatory enzyme of glycolysis?
PFK-1 (Phosphofructokinase-1).
p.79
Metabolism: Catabolism and Anabolism
What happens to PFK-2 during fasting?
PFK-2 is phosphorylated, making it inactive.
p.84
Digestive Enzymes and Their Functions
What is the first oxidation-reduction reaction of glycolysis?
The oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.
p.86
Digestive Disorders and Malabsorption Issues
How does pentavalent arsenic (arsenate) affect glycolysis?
It prevents net ATP and NADH production by competing with Pi as a substrate for glyceraldehyde 3-phosphate dehydrogenase.
p.59
Metabolic Disorders and Malabsorption Issues
What mainly causes metabolic diseases or inborn errors of metabolism?
Genetic enzyme deficiencies.
p.74
Metabolism: Catabolism and Anabolism
What can glucose-6-phosphate be converted into?
It can be converted into glucose, glycogen, or enter the pentose phosphate pathway.
p.81
Digestive Enzymes and Their Functions
Is the cleavage reaction catalyzed by aldolase reversible?
Yes, the reaction is reversible.
p.79
Metabolism: Catabolism and Anabolism
What hormones are elevated during the well-fed state?
Insulin levels are elevated, and glucagon levels are decreased.
p.93
Metabolism: Catabolism and Anabolism
What occurs in Reaction 8 of glycolysis?
The phosphate group shifts from carbon 3 to carbon 2 of phosphoglycerate, forming 2-Phosphoglycerate.
p.89
Metabolism: Catabolism and Anabolism
What is the Rapoport Luebering Glycolytic Shunt?
A modified glycolysis pathway in RBCs that includes shunt reactions.
p.69
Digestive Enzymes and Their Functions
Why is a high affinity for glucose beneficial for hexokinase?
It allows efficient phosphorylation and metabolism of glucose even at low tissue concentrations.
p.93
Metabolism: Catabolism and Anabolism
What characterizes phosphoenolpyruvate (PEP)?
It contains a high-energy enol phosphate.
p.67
Carbohydrate Digestion and Absorption
What is the consequence of the irreversible phosphorylation of glucose?
It traps glucose as cytosolic glucose-6-phosphate, committing it to further metabolism.
p.89
Metabolism: Catabolism and Anabolism
Why is 2,3-BPG present at high concentrations in RBCs?
Because it plays a crucial role in oxygen delivery, unlike most cells where it is found in trace amounts.
p.80
Regulation of Glycolysis
How does PFK-II relate to F-2,6-bisP?
PFK-II synthesizes F-2,6-bisP and is regulated by phosphorylation.
p.57
Metabolism: Catabolism and Anabolism
What pathway generates NADPH and ribose-5-phosphate for nucleotide synthesis?
Pentose phosphate shunt pathway.
p.91
Metabolism: Catabolism and Anabolism
What is the primary function of the Rapoport-Luebering glycolytic shunt in red blood cells (RBCs)?
To generate 2,3-bisphosphoglycerate (2,3-BPG), which regulates oxygen release from hemoglobin.
p.92
Metabolism: Catabolism and Anabolism
What is produced from 3-Phosphoglycerate during glycolysis?
Pyruvate is ultimately produced after further conversion.
p.78
Metabolism: Catabolism and Anabolism
What is the effect of fructose-2,6-bisphosphate on PFK-1?
It acts as a potent activator of PFK-1.
p.67
Carbohydrate Digestion and Absorption
What is the first reaction in the glycolytic pathway involving glucose?
The phosphorylation of glucose to glucose-6-phosphate.
p.87
Metabolism: Catabolism and Anabolism
What is produced during the conversion of 1,3-BPG to 3-phosphoglycerate?
ATP is synthesized from ADP.
p.93
Metabolism: Catabolism and Anabolism
Is the reaction forming PEP reversible?
Yes, despite the high-energy nature of the product.
p.87
Metabolism: Catabolism and Anabolism
What type of phosphorylation is described in this reaction?
Substrate-level phosphorylation.
p.80
Regulation of Glycolysis
What inhibits pyruvate kinase?
ATP, acetyl CoA, and phosphorylation.
p.57
Metabolism: Catabolism and Anabolism
What process occurs in the mitochondria to produce ATP using electron transport?
Oxidative phosphorylation.
p.63
Metabolism: Catabolism and Anabolism
What is glycolysis?
A metabolic pathway that converts glucose into pyruvate, generating ATP and NADH.
p.79
Metabolism: Catabolism and Anabolism
What effect does a carbohydrate-rich meal have on fructose 2,6-bisphosphate?
It increases the levels of hepatic fructose 2,6-bisphosphate.
p.79
Metabolism: Catabolism and Anabolism
What is the role of fructose 2,6-bisphosphate in the well-fed state?
It acts as an intracellular signal of glucose abundance, increasing glycolysis and inhibiting gluconeogenesis.
p.83
Metabolism: Catabolism and Anabolism
What is dihydroxyacetone phosphate (DHAP) used for?
It is used for the synthesis of glycerol-3-phosphate utilized in triacylglycerol synthesis.
p.93
Metabolism: Catabolism and Anabolism
What role does enolase play in the conversion of 2-Phosphoglycerate?
Enolase catalyzes the dehydration of 2-Phosphoglycerate to form PEP.
p.89
Metabolism: Catabolism and Anabolism
Why is the lack of ATP production advantageous for RBCs?
It allows the accumulation of 2,3-BPG and enables glycolysis to proceed when ATP needs are minimal.
p.72
Metabolism: Catabolism and Anabolism
How is glucokinase regulated in the body?
Its synthesis is induced by insulin and repressed in diabetes.
p.86
Digestive Disorders and Malabsorption Issues
What does arsenate form when it competes with Pi?
A complex that spontaneously hydrolyzes to form 3-phosphoglycerate.
p.56
Metabolism: Catabolism and Anabolism
What are the two major phases of glycolysis?
The energy investment phase and the energy payoff phase.
p.63
Metabolism: Catabolism and Anabolism
How many ATP molecules are produced during glycolysis?
A net gain of 2 ATP molecules per glucose molecule.
p.72
Metabolism: Catabolism and Anabolism
What is the function of glucokinase in the liver following a carbohydrate-rich meal?
It requires a higher glucose concentration for half-saturation, functioning effectively when intracellular glucose levels are elevated.
p.63
Metabolism: Catabolism and Anabolism
What happens to pyruvate after glycolysis under anaerobic conditions?
It is converted to lactic acid or ethanol, depending on the organism.
p.72
Metabolism: Catabolism and Anabolism
What role does GLUT-2 play in glucose metabolism?
It ensures that blood glucose equilibrates rapidly across the hepatocyte membrane.
p.84
Metabolism: Catabolism and Anabolism
What are the two major mechanisms for oxidizing NADH to NAD+?
Reduction of pyruvate to lactate by lactate dehydrogenase and the electron transport chain.
p.57
Metabolism: Catabolism and Anabolism
What metabolic processes involve the formation and breakdown of glycogen?
Glycogenesis and glycogenolysis.
p.69
Digestive Enzymes and Their Functions
What is the function of glucose-6-phosphate in relation to hexokinase?
It inhibits hexokinase to control glucose uptake in extrahepatic tissues.
p.93
Metabolism: Catabolism and Anabolism
What happens in Reaction 9 of glycolysis?
2-Phosphoglycerate undergoes dehydration to form phosphoenolpyruvate (PEP).
p.89
Metabolism: Catabolism and Anabolism
What is the ATP production status when glycolysis takes the Rapoport Luebering Shunt pathway?
There is no production of ATP.
p.84
Digestive Enzymes and Their Functions
What enzyme catalyzes the oxidation of glyceraldehyde 3-phosphate?
Glyceraldehyde 3-phosphate dehydrogenase.
p.86
Digestive Disorders and Malabsorption Issues
What is arsenate poisoning in the context of glycolysis?
It bypasses the synthesis of 1,3-BPG, depriving the cell of energy normally obtained from glycolysis.
p.80
Regulation of Glycolysis
What primarily controls the rate of glycolysis?
Allosteric regulation of three key enzymes: hexokinase, PFK-1, and pyruvate kinase.
p.89
Metabolism: Catabolism and Anabolism
What is the primary role of 2,3-BPG in RBCs?
To increase oxygen delivery by enabling the unloading of oxygen from oxyhemoglobin.
p.87
Metabolism: Catabolism and Anabolism
How many molecules of 1,3-BPG are formed from each glucose molecule?
Two molecules of 1,3-BPG.
p.89
Metabolism: Catabolism and Anabolism
What enzyme converts 1,3-BPG to 2,3-BPG in RBCs?
Bisphosphoglycerate mutase.
p.93
Metabolism: Catabolism and Anabolism
What is the purpose of fluoride/oxalate bottles in blood collection?
To preserve the carbons of glucose for estimation.
p.67
Carbohydrate Digestion and Absorption
What is the role of ATP in glucose phosphorylation?
ATP is used to phosphorylate glucose, converting it to glucose-6-phosphate.
p.89
Metabolism: Catabolism and Anabolism
How is 2,3-BPG converted back to an intermediate in glycolysis?
It is hydrolyzed by a phosphatase to 3-phosphoglycerate.
p.87
Metabolism: Catabolism and Anabolism
What does the kinase reaction replace regarding ATP usage?
It replaces the two ATP molecules consumed by the earlier formation of glucose 6-phosphate and fructose 1,6-bisphosphate.
p.86
Metabolism: Catabolism and Anabolism
What happens to the aldehyde group of glyceraldehyde 3-phosphate during oxidation?
It is oxidized to a carboxyl group, coupled with the attachment of Pi.
p.93
Metabolism: Catabolism and Anabolism
How does fluoride affect enolase?
Fluoride inhibits enolase.
p.87
Metabolism: Catabolism and Anabolism
Where does the energy for ATP production come from in substrate-level phosphorylation?
From a high-energy substrate rather than from the electron transport chain (ETC).
p.80
Regulation of Glycolysis
What hormone inhibits glycolysis?
Glucagon, by repressing the synthesis of F-2,6-bisP.
p.57
Metabolism: Catabolism and Anabolism
What is the process of breaking down and synthesizing amino acids called?
Amino acid degradation and synthesis.
