Logo
memo(formerly PDF2Anki)
What type of enzyme acts on the 5’-end of primary tRNA transcripts? A) Endonuclease B) Exonuclease C) Ribozyme D) DNA polymerase E) RNA polymerase
A) Endonuclease Explanation: An endonuclease acts on the 5’-end of primary tRNA transcripts, playing a crucial role in the processing of tRNA molecules.
What is a major catabolic product of pyrimidines in humans? A) Uric acid B) Beta-alanine C) Urea D) Fumarate E) Dihydrofolate
D) Fumarate Explanation: Fumarate is a significant catabolic product of pyrimidines in humans, resulting from the breakdown of these nucleotides, which plays a role in various metabolic pathways.
1/32
p.3
RNA Processing and Splicing

What type of enzyme acts on the 5’-end of primary tRNA transcripts?
A) Endonuclease
B) Exonuclease
C) Ribozyme
D) DNA polymerase
E) RNA polymerase

A) Endonuclease
Explanation: An endonuclease acts on the 5’-end of primary tRNA transcripts, playing a crucial role in the processing of tRNA molecules.

p.6
Catabolism of Pyrimidines

What is a major catabolic product of pyrimidines in humans?
A) Uric acid
B) Beta-alanine
C) Urea
D) Fumarate
E) Dihydrofolate

D) Fumarate
Explanation: Fumarate is a significant catabolic product of pyrimidines in humans, resulting from the breakdown of these nucleotides, which plays a role in various metabolic pathways.

p.1
Enzyme Inhibition Mechanisms

A substrate that causes a conformational change in an enzyme to enhance its own binding is:
A) Competitive inhibitor
B) Heterotropic modulator
C) Homotropic modulator
D) Inactivator
E) Uncompetitive inhibitor

C) Homotropic modulator
Explanation: A homotropic modulator is a substrate that binds to an enzyme and induces a conformational change that enhances its own binding, thus facilitating the reaction.

p.3
Kinetic Parameters in Enzyme Reactions

Which of the following can influence the speed of an enzyme's reaction without affecting its equilibrium position?
A) ΔG reaction
B) ΔG ±
C) ΔH reaction
D) Q, the reaction quotient
E) Temperature

D) Q, the reaction quotient
Explanation: The reaction quotient (Q) can influence the rate at which an enzyme speeds up a reaction, but it does not change the position of the equilibrium.

p.1
Enzyme Inhibition Mechanisms

What effect does the presence of a substrate analog (an inhibitor) have on the reaction catalyzed by the enzyme?
A) Decrease
B) Increase
C) No change
D) Not enough information
E) Stabilize

A) Decrease
Explanation: The presence of a substrate analog, which acts as an inhibitor, would typically decrease the rate of the reaction by competing with the natural substrate for binding to the enzyme.

p.6
RNA Processing and Splicing

What does a decrease in light absorbance at 260 nm indicate?
A) Increase in DNA concentration
B) Degradation of nucleic acids
C) Formation of a double helix
D) Increase in RNA concentration
E) Presence of proteins

B) Degradation of nucleic acids
Explanation: A decrease in light absorbance at 260 nm typically indicates the degradation of nucleic acids, as intact DNA and RNA absorb light at this wavelength.

p.2
Cofactors and Their Biological Roles

Which of the following is a cofactor derived from the B-vitamin niacin (B3)?
A) Biotin
B) Nicotinamide adenine dinucleotide (NAD)
C) Coenzyme A
D) Thiamine pyrophosphate (TPP)
E) Flavin adenine dinucleotide (FAD)

B) Nicotinamide adenine dinucleotide (NAD)
Explanation: NAD is a cofactor that is derived from niacin (B3) and plays a crucial role in various metabolic processes, including oxidation-reduction reactions.

p.5
Thermal Denaturation of DNA

Thermal denaturation of DNA is characterized by:
A) A broad (100°C) denaturation range for a homogenous DNA molecule.
B) Cleavage of the phosphodiester linkages between bases
C) A sharp denaturation point at 75°C
D) The formation of secondary structures
E) The complete loss of all hydrogen bonds

A) A broad (100°C) denaturation range for a homogenous DNA molecule.
Explanation: Thermal denaturation of DNA typically occurs over a range of temperatures, reflecting the stability of the DNA molecule and the interactions between base pairs.

p.1
Cofactors and Their Biological Roles

Which of the following cofactors can serve as an activated carrier of electrons for reductive biosynthesis?
A) NAD+
B) FAD
C) Coenzyme A
D) ATP
E) Biotin

A) NAD+
Explanation: NAD+ serves as an activated carrier of electrons in various biochemical reactions, particularly in reductive biosynthesis, by accepting electrons and becoming reduced to NADH.

p.6
Thermal Denaturation of DNA

What is a characteristic of DNA melting-point temperature?
A) It varies inversely with adenine-thymine base-pair content
B) It remains constant regardless of base-pair content
C) It varies directly with guanine-cytosine base-pair content
D) It is lower than that of RNA
E) It is unaffected by temperature changes

C) It varies directly with guanine-cytosine base-pair content
Explanation: The melting-point temperature of DNA increases with the guanine-cytosine base-pair content due to the stronger hydrogen bonding between these base pairs compared to adenine-thymine pairs.

p.4
Anticancer Agents and Mechanisms

Which of the following agents is classified as an anti-cancer, folate antagonist?
A) Aminopterin
B) Ciprofloxacin
C) Actinomycin
D) Fluorouracil
E) Rifampicin

A) Aminopterin
Explanation: Aminopterin is known as an anti-cancer agent that acts as a folate antagonist, inhibiting the synthesis of nucleotides necessary for DNA replication, thus affecting rapidly dividing cancer cells.

p.1
Kinetic Parameters in Enzyme Reactions

How would the substrate analog (inhibitor) affect the apparent Vmax of the reaction catalyzed by the same enzyme?
A) Decrease
B) Increase
C) No change
D) Not enough information
E) Stabilize

C) No change
Explanation: The apparent Vmax of the reaction remains unchanged because the inhibitor does not affect the maximum rate of reaction when enough substrate is present; it primarily affects the Km.

p.1
Enzyme Inhibition Mechanisms

What type of inhibition is evident from the attached plot, and which kinetic parameter is changed?
A) Competitive inhibition: Km
B) Mixed inhibition: Vmax
C) No inhibition: Vmax stays the same
D) Non-competitive inhibition: Km
E) Uncompetitive inhibition: Vmax

A) Competitive inhibition: Km
Explanation: In competitive inhibition, the Km increases because the inhibitor competes with the substrate for the active site, while Vmax remains unchanged.

p.3
RNA Processing and Splicing

How does prokaryotic mRNA differ from eukaryotic mRNA?
A) Can be translated during transcription
B) Requires a primer for synthesis
C) Is synthesized in a 5’ to 3’ direction
D) Contains introns
E) Is polyadenylated

A) Can be translated during transcription
Explanation: Prokaryotic mRNA can be translated while it is still being transcribed, which is a key difference from eukaryotic mRNA that undergoes additional processing before translation.

p.4
RNA Processing and Splicing

Which method is specifically used to detect RNA and measure differences in levels of specific mRNAs in different tissues?
A) DNA fingerprint analysis
B) Northern blot analysis
C) Restriction fragment length polymorphism (RFLP) linkage analysis
D) Southern blot analysis
E) Western blot analysis

B) Northern blot analysis
Explanation: Northern blot analysis is a technique specifically designed to detect and quantify RNA, allowing researchers to measure the expression levels of specific mRNAs across different tissues.

p.5
Enzyme Inhibition Mechanisms

Which of the following statements is true regarding enzyme inhibitors?
A) The apparent Km is smaller in the presence of the inhibitor
B) The inhibitor binds to the substrate
C) The inhibitor binds to the allosteric site of the enzyme
D) The inhibitor can be overcome with progressively higher concentrations of substrate
E) The inhibitor reacts with a different critical residue of the enzyme

D) The inhibitor can be overcome with progressively higher concentrations of substrate
Explanation: This statement describes a competitive inhibitor, which can be overcome by increasing substrate concentration, thereby increasing the likelihood of substrate binding to the active site.

p.3
Thermal Denaturation of DNA

Which single-stranded DNA molecule would be palindromic in the double-stranded state?
A) ATGCCGTA
B) ATGCTACG
C) GCTATGAC
D) CTATCTAT
E) GTCATGAC

D) CTATCTAT
Explanation: The sequence CTATCTAT is palindromic because its complementary base pairs would read the same backward in the double-stranded state.

p.5
Enzyme Inhibition Mechanisms

What is the common strategy by which catalysis occurs, and what part of an enzyme binds to the substrate?
A) Decreasing the concentration of active enzyme; active site
B) Increasing the probability of product formation; initiation site
C) Shifting the reaction equilibrium; transformation site
D) Stabilization of the concentration of active enzyme; active site

D) Stabilization of the concentration of active enzyme; active site
Explanation: The active site of an enzyme binds to the substrate, stabilizing the transition state and increasing the likelihood of product formation.

p.3
RNA Processing and Splicing

What does it mean that the genetic code is degenerate?
A) Most tRNAs transport more than one amino acid
B) Most life forms use the same three-letter (triplet) code to specify amino acids
C) Most codons specify more than one amino acid
D) Most aminoacyl-tRNA synthetases can utilize more than one amino acid
E) Most amino acids are specified by more than one codon

E) Most amino acids are specified by more than one codon
Explanation: The degeneracy of the genetic code refers to the fact that most amino acids are encoded by more than one codon, allowing for some redundancy in the genetic code.

p.6
RNA Processing and Splicing

What is a unique feature of the formation of a triple helix in nucleic acids?
A) It requires only adenine and thymine
B) It is more stable than a double helix
C) It involves three strands of nucleotides
D) It is a common form of RNA
E) It occurs only in prokaryotes

C) It involves three strands of nucleotides
Explanation: The formation of a triple helix involves three strands of nucleotides, which is a unique structural feature compared to the more common double helix structure of DNA.

p.2
Kinetic Parameters in Enzyme Reactions

What effect does activated AMPK (AMP-activated protein kinase) have?
A) Stimulates insulin secretion by the pancreas
B) Promotes fatty acid synthesis and deposition in adipose tissue
C) Stimulates glycogen synthesis in the liver
D) Enhances cholesterol synthesis in the liver
E) Increases glucose uptake by skeletal muscle

E) Increases glucose uptake by skeletal muscle
Explanation: Activated AMPK promotes energy-generating processes, including increasing glucose uptake in skeletal muscle, which is crucial during low-energy states.

p.4
Polymerase Chain Reaction (PCR) Applications

What is a major advantage of the polymerase chain reaction (PCR) technique?
A) Allows amplification of specific DNA sequences
B) Allows insertion of genes that can replicate
C) Allows synthesis of mRNA
D) Can be performed at 98.6°F
E) Requires highly purified and cloned DNA

A) Allows amplification of specific DNA sequences
Explanation: The primary advantage of PCR is its ability to amplify specific DNA sequences, making it a powerful tool in molecular biology for various applications such as cloning, gene analysis, and forensic science.

p.3
Genome Editing Technologies

What does the SARS-CoV-2 viral genome provide information for?
A) DNA-dependent DNA polymerase
B) DNA-dependent RNA polymerase
C) rRNAs
D) tRNAs
E) Viral polypeptides (proteins)

E) Viral polypeptides (proteins)
Explanation: The SARS-CoV-2 viral genome contains the information necessary for the immediate production of viral polypeptides (proteins), which are essential for the virus's replication and function.

p.2
Genome Editing Technologies

Which genome editing tool utilizes a guide RNA (gRNA) for targeting specific DNA sequences?
A) CRISPR/Cas9
B) PCR
C) siRNA
D) TALENs
E) ZFNs

A) CRISPR/Cas9
Explanation: CRISPR/Cas9 is a revolutionary genome editing technology that uses guide RNA to direct the Cas9 enzyme to specific DNA sequences for editing.

p.4
Kinetic Parameters in Enzyme Reactions

At equilibrium, which statement is true regarding the moles of ATP and ADP?
A) More moles of ADP than ATP
B) More moles of ATP than ADP
C) Equal moles of ATP and ADP
D) Cannot tell from this information given

C) Equal moles of ATP and ADP
Explanation: At equilibrium in a closed system, the concentrations of ATP and ADP will stabilize, leading to a balance where the moles of ATP and ADP are equal, assuming no external influences.

p.5
RNA Processing and Splicing

What mechanism allows for the production of calcitonin and calcitonin gene-related proteins?
A) A polycistronic eukaryotic mRNA
B) An alternative splicing and polyadenylation choice mechanism
C) RNA editing
D) The recombination of two different segments of DNA
E) The transcription of the two genes coding for them

B) An alternative splicing and polyadenylation choice mechanism
Explanation: Calcitonin and calcitonin gene-related proteins are produced through alternative splicing, which allows for different protein products from the same gene.

p.2
Genome Editing Technologies

What is the biological role of restriction enzymes?
A) Aid recombinant DNA research
B) Degrade foreign DNA that enters a bacterium
C) Make bacteria resistant to antibiotics
D) Restrict the damage to DNA by UV light
E) Restrict the size of DNA in certain bacteria

B) Degrade foreign DNA that enters a bacterium
Explanation: Restriction enzymes function primarily to recognize and cut foreign DNA, such as that from viruses, thereby protecting bacteria from potential threats.

p.2
RNA Processing and Splicing

What type of enzyme is RNase D?
A) Endonuclease on the 3’-end of primary tRNA transcripts
B) Exonuclease on the 5’-end of mRNA
C) Ligase for DNA fragments
D) Polymerase for RNA synthesis
E) Helicase for unwinding DNA

A) Endonuclease on the 3’-end of primary tRNA transcripts
Explanation: RNase D is specifically an endonuclease that acts on the 3’-end of primary tRNA transcripts, playing a role in RNA processing.

p.4
Histone Function and Characteristics

How are histones best described?
A) Acidic proteins containing a high proportion of glutamic and aspartic acid residues
B) Basic proteins containing a high proportion of lysine and arginine residues
C) Proteins that bind with rRNA to form ribosomes
D) Proteins that primarily bind to mitochondrial DNA
E) Proteins that control the rate of mRNA translation

B) Basic proteins containing a high proportion of lysine and arginine residues
Explanation: Histones are basic proteins rich in lysine and arginine, which play a crucial role in DNA packaging and regulation of gene expression by forming nucleosomes.

p.5
RNA Processing and Splicing

Which of the following is a component of the splicing reactions necessary to convert heterogeneous nuclear (hnRNA) to mature mRNA in eukaryotes?
A) Poly (A) polymerase
B) Ribonuclease P
C) Small nuclear ribonucleoprotein (snRNP)
D) The sequence AAUAAA within the intron
E) The sequences guanine-uracil and adenine-thymine

C) Small nuclear ribonucleoprotein (snRNP)
Explanation: snRNPs are essential components of the spliceosome, which is responsible for the splicing of hnRNA to produce mature mRNA.

p.4
Enzyme Inhibition Mechanisms

What conclusion can be drawn if the Vmax is the same in the presence of an inhibitor?
A) The inhibitor is a competitive inhibitor
B) The inhibitor is a non-competitive inhibitor
C) The inhibitor has no effect on the enzyme
D) The inhibitor increases the reaction rate
E) The inhibitor is irreversible

B) The inhibitor is a non-competitive inhibitor
Explanation: If Vmax remains unchanged in the presence of an inhibitor, it indicates that the inhibitor does not affect the maximum rate of reaction, characteristic of non-competitive inhibition.

p.5
Kinetic Parameters in Enzyme Reactions

Which one of the following DNA polymerases is essential for both replication and removal of RNA primers?
A) DNA Polymerase I
B) DNA polymerase α
C) DNA polymerase II
D) DNA polymerase δ

A) DNA Polymerase I
Explanation: DNA Polymerase I is crucial for removing RNA primers during DNA replication and replacing them with DNA, making it essential for both processes.

Study Smarter, Not Harder
Study Smarter, Not Harder