p.13
Membrane Fluidity and Asymmetry
What is the function of scramblase in relation to phosphatidylserine?
Scramblase flips PS to the extracellular side, causing a negative charge outside.
p.1
Hemochromatosis and Iron Overload
What is hemochromatosis?
A condition of iron overload affecting organs such as the liver, heart, and endocrine organs.
Which lipoprotein has the most protein and the least triglycerides?
HDL (High-Density Lipoprotein).
p.1
Hemochromatosis and Iron Overload
What is a severe form of hemochromatosis caused by?
A hepcidin-resistant ferroportin.
p.5
Lipid Transport Mechanisms
What happens to the vesicle after it fuses with the plasma membrane?
It continues the process until the LDL receptor has lived its lifespan.
p.7
Membrane Lipid Composition and Structure
What types of lipids are found in the outer leaflet of the membrane?
Glycolipids and glycoproteins.
p.6
Familial Hypercholesterolemia
What happens to LDL in the bloodstream due to the receptor mutation?
The receptor does not take up LDL from the bloodstream.
p.6
Membrane Lipid Composition and Structure
How does the composition of lipid bilayers vary?
Compositions vary based on the specific membrane and its functions.
p.11
Membrane Fluidity and Asymmetry
How do saturated fatty acids affect cholesterol and membrane fluidity?
Saturated fatty acids insert cholesterol, spacing out phospholipids and increasing fluidity, but too much cholesterol reduces fluidity.
p.13
Membrane Fluidity and Asymmetry
Why is phosphatidylserine (PS) important to stay in the inner leaflet of the membrane?
Changes in membrane asymmetry can lead to disease.
p.13
Membrane Fluidity and Asymmetry
What diseases are associated with membrane asymmetry?
Sickle-cell anemia, thalassemia, kidney stones, malaria, and pre-eclampsia.
p.1
Anemia Causes and Types
What is hemolytic anemia?
A type of anemia caused by increased destruction of red blood cells, often via macrophages.
p.12
Lipid Transport Proteins and Mechanisms
What does Scramblase require to function?
Calcium; it is not ATP dependent.
p.3
Lipid Transport Mechanisms
What role do adipose cells play in lipid transport?
They extract lipids from chylomicrons via lipoprotein lipases.
p.3
Lipid Transport Mechanisms
How can adipose tissue send lipids to the liver?
In water-soluble carriers.
p.6
Familial Hypercholesterolemia
What are the consequences of too much cholesterol and triglycerides in the bloodstream?
Formation of plaques leading to heart attacks.
p.2
Lipid Absorption and Emulsification
What are bile salts and their characteristics?
Bile salts are amphipathic molecules, meaning one half is hydrophobic and the other half is hydrophilic.
p.9
Membrane Lipid Composition and Structure
What charge does Phosphatidyl carry?
It is negatively charged.
p.13
Membrane Fluidity and Asymmetry
What role do macrophages play in the process of apoptosis related to PS?
Macrophages recognize the exposed PS and facilitate the process of apoptosis.
p.1
Anemia Causes and Types
What are the main causes of anemia?
1. Blood loss 2. Decrease in red blood cell production due to iron deficiencies 3. Increased destruction of red blood cells (hemolytic anemias).
What are chylomicrons composed of?
Cholesterol, triglycerides, phospholipids, and apolipoproteins.
p.4
Lipid Transport Mechanisms
Which lipoproteins are made by the liver?
VLDL (Very-Low-Density Lipoprotein) and LDL (Low-Density Lipoprotein).
p.3
Lipid Transport Mechanisms
What happens to chylomicrons after lipids are extracted?
They shrink down and become chylomicrons lacking fats.
p.3
Lipid Transport Mechanisms
What can excess cholesterol and triglycerides do in the liver?
They can be stored or sent to the rest of the body in water-soluble carriers.
p.7
Membrane Fluidity and Asymmetry
How does the asymmetry of the lipid bilayer affect the shape of cells or organelles?
It directs the overall shape of the cell or organelle.
p.2
Lipid Absorption and Emulsification
What is emulsification?
The breaking down of lipids using bile salts.
p.2
Lipid Absorption and Emulsification
How is cholesterol transported into cells?
Via Niemann-Pick protein.
p.13
Membrane Fluidity and Asymmetry
What happens when phosphatidylserine is exposed on the outer leaflet?
It serves as a recognition signal for apoptosis to proceed.
p.1
Anemia Causes and Types
What are some solutions for treating anemia?
Take more iron, consume red meat, or receive blood transfusions.
p.3
Lipid Transport Mechanisms
How do lipids travel from the intestines to the bloodstream?
Through lacteals to the bloodstream (to vena cava).
p.7
Membrane Lipid Composition and Structure
What are glycoproteins and glycolipids?
Carbohydrates that are attached to proteins or lipids.
p.7
Membrane Lipid Composition and Structure
What is the asymmetry of the lipid bilayer?
Inner and outer leaflets have different lipid types.
p.6
Familial Hypercholesterolemia
What is the effect of heterozygous mutations on LDL levels?
Heterozygotes have 2x LDL in blood and develop cardiovascular disease.
p.6
Membrane Lipid Composition and Structure
What components are found in a lipid bilayer?
Lipids, proteins, cholesterol, glycolipids, and glycoproteins.
p.9
Membrane Lipid Composition and Structure
What is the general structure of glycerophospholipids?
Always consists of Phosphatidyl + R group.
p.11
Membrane Fluidity and Asymmetry
What is the relationship between temperature and membrane fluidity?
Higher temperatures increase membrane fluidity, as seen with butter at room temperature.
p.9
Membrane Lipid Composition and Structure
What is the relationship between cholesterol and phospholipids in certain membrane regions?
There is as much cholesterol as phospholipid in certain regions, such as lipid rafts.
p.10
Membrane Fluidity and Asymmetry
What is the saturation level of stearic acid?
Completely saturated (no double bonds).
p.13
Membrane Fluidity and Asymmetry
What happens to the activity of flippase and floppase during the exposure of PS?
Flippase and floppase are downregulated, allowing scramblase to take over.
p.5
Lipid Transport Mechanisms
What occurs as the lumen of the endosome becomes more acidic?
LDL dissociates from the receptor.
p.7
Membrane Lipid Composition and Structure
Why are there no carbohydrates in the mitochondrial inner membrane?
Proteins and lipids do not go into the ER and do not get glycosylated.
p.4
Lipid Transport Proteins and Mechanisms
What occurs after the LDL receptor binds to its ligand?
The receptor-ligand migrates to the clathrin-coated pit.
p.6
Familial Hypercholesterolemia
What gene mutation is associated with high LDL levels?
The mutation is in the LDL receptor.
p.2
Lipid Absorption and Emulsification
What role do pancreatic lipases and colipases play in lipid digestion?
They break down fats into monoglycerides, which are stored in micelles.
p.2
Chylomicron Formation and Transport
How do chylomicrons enter the bloodstream?
Indirectly through the lymphatic system.
p.10
Membrane Fluidity and Asymmetry
What characterizes an unsaturated fatty acid?
Presence of double bonds.
p.12
Membrane Fluidity and Asymmetry
What are the two types of slow lipid movements across the membrane?
Monomeric exchange and Transbilayer movement.
p.12
Lipid Transport Proteins and Mechanisms
What is the function of Floppase?
Moves lipids from the inner to the outer leaflet and is ATP dependent.
p.12
Lipid Transport Proteins and Mechanisms
What is the role of Scramblase in lipid movement?
Indiscriminately exchanges lipids from the outer to inner or inner to outer leaflet.
p.1
Hemochromatosis and Iron Overload
What happens in hereditary hemochromatosis?
Ferroportin doesn't respond to hepcidin, leading to excess iron in circulation.
p.5
Lipid Transport Mechanisms
What happens to the receptor after processing?
The receptor goes back to the cell membrane and is recycled.
p.4
Lipid Transport Proteins and Mechanisms
What is the first step in the internalization of LDL?
Ligand (LDL) binds to the receptor.
What is the relationship between VLDL, LDL, HDL, and chylomicrons?
They interact in the lipid transport process.
p.10
Membrane Fluidity and Asymmetry
How does the level of unsaturated to saturated fatty acids affect membrane fluidity?
More double bonds increase flexibility; more single bonds increase rigidity.
p.4
Lipid Transport Mechanisms
What happens to HDL after it performs its function?
It is returned to the liver.
p.3
Lipid Transport Mechanisms
Where do chylomicrons go after losing fats?
They go to the liver to be metabolized.
p.7
Membrane Fluidity and Asymmetry
What is one function of the asymmetry of the lipid bilayer?
It provides curvatures of membranes.
p.6
Membrane Lipid Composition and Structure
What is the structure of a lipid bilayer?
A dynamic structure composed of phospholipids.
p.2
Lipid Absorption and Emulsification
How do bile salts help in lipid digestion?
The hydrophilic exterior keeps lipids soluble, allowing for better emulsification.
p.11
Membrane Fluidity and Asymmetry
Where are glycolipids located in the plasma membrane?
On the outer membrane of the plasma membrane.
p.10
Membrane Fluidity and Asymmetry
How do you count the degree of saturation in a fatty acid?
From the end of the fatty acid, not from the OH group.
p.12
Lipid Transport Proteins and Mechanisms
What is the function of Flippase?
Moves lipids from the outer to the inner leaflet and is ATP dependent.
p.5
Lipid Transport Mechanisms
What happens to clathrin after endocytosis?
Clathrin is recycled and loses its coat.
p.5
Lipid Transport Mechanisms
Where do ligands go after dissociation from the receptor?
To either the lysosome or the Golgi apparatus for processing.
p.1
Hemochromatosis and Iron Overload
How can iron overload be treated?
Through phlebotomy (blood-letting) to reduce blood iron levels.
p.6
Familial Hypercholesterolemia
What is the effect of homozygous mutations on LDL levels?
Homozygotes have 4-6x LDL in blood and may experience heart attacks in their 20s.
p.6
Membrane Lipid Composition and Structure
What are the four ways recycling occurs in membrane bilayers?
Transport, biosynthesis, and two other unspecified methods.
p.9
Membrane Lipid Composition and Structure
What is the fatty acid carbon range typically found in glycerophospholipids?
Usually 16-18 carbons, with a range of 12-22.
p.11
Lipid Transport Mechanisms
What is monomeric exchange?
It involves the exchange of monomeric lipids between mitochondria, ER, and the plasma membrane.
p.6
Membrane Lipid Composition and Structure
How does the lipid bilayer maintain itself?
Through continuous replacement and recycling.
p.2
Lipid Absorption and Emulsification
What happens to fatty acids after emulsification?
Fatty acids diffuse into cells.
p.11
Lipid Transport Mechanisms
What are the four types of lipid transport within the cell?
Lateral diffusion, vesicular transport, monomeric exchange, and transbilayer movement.
p.9
Membrane Lipid Composition and Structure
What are the two types of R groups in glycerophospholipids?
1. Positively charged (e.g., Choline, Ethanolamine) 2. Neutral (e.g., Inositol, Serine).
p.2
Chylomicron Formation and Transport
Why are chylomicrons removed by the lymphatic system?
Because they are too large to enter capillaries but can enter lacteals.
p.11
Membrane Fluidity and Asymmetry
What is the distribution of phosphatidylcholine (PC) in the plasma membrane?
More PC is found in the outer membrane of the plasma membrane.
p.2
Chylomicron Formation and Transport
What happens to chylomicrons after they are formed?
They are transported through the Golgi apparatus and then secreted.
p.11
Membrane Fluidity and Asymmetry
What is the role of phosphatidylinositol (PI) in cellular membranes?
PI is found on endosomes.
p.11
Membrane Fluidity and Asymmetry
What are lipid rafts?
Less fluid domains in the membrane that can be affected by cholesterol levels; too much or too little cholesterol can be detrimental.
p.9
Membrane Lipid Composition and Structure
How do the fatty acids differ between plasma membranes and organelles?
Plasma membranes have more saturated fatty acids, while organelles have more unsaturated fatty acids.
p.11
Membrane Fluidity and Asymmetry
Where is phosphatidylserine (PS) located in the plasma membrane?
In the inner membrane of the plasma membrane.
p.11
Lipid Transport Mechanisms
How common is transbilayer movement of lipids?
Transbilayer movement is very rare.
p.11
Lipid Transport Mechanisms
How fast is lateral diffusion of lipids?
Lateral diffusion is fast.
p.11
Lipid Transport Mechanisms
What characterizes vesicular transport?
It is relatively fast and relies on microtubules.
