2011 biochem midterm Flashcards
Which of the following is the last step in DNA synthesis?
A. removal of primers
B. primer binding
C. addition of nucleotide by polymerase
D. ligation of newly synthesized strands
E. separation of DNA strands
D. ligation of newly synthesized strands
What is the biochemical role of vitamin C? A. cross-linkage B. collagen degradation C. protein folding D. hydroxylation of proline E. glycosylation
D. hydroxylation of proline
What happens to albumin in egg white when the egg is boiled? A. degradation B. denaturation C. lipidation D. oligomerization E. hydroxylation
B. denaturation
A competitive inhibitor was introduced to an enzyme catalyzed reaction. What is the effect of this on enzyme activity? A. increase Vmax B. decrease Vmax C. no effect D. decrease Km E. Increase Km
E. Increase Km
What is the effect of nucleotide analogs when they are administered? A. inhibition of DNA synthesis B. catalyze elongation C. degrade the DNA D. denaturation
A. inhibition of DNA synthesis
Which one does NOT affect glycogen degradation in muscles? A. ATP B. AMP C. glucagon D. epinephrine E. Glucose-6-phosphate
C. glucagon
What is the function of copper in the collagen structure? A. Cross-linking B. Hydroxylation C. Glycosylation D. Amino acid removal E. Degradation
A. Cross-linking
What is a metaphasic chromosome? A. naked DNA molecule without histones B. single-stranded DNA C. 4 DNA stands with histones D. double-stranded DNA molecule with histones E. uncompacted DNA
C. 4 DNA stands with histones
What is the action of restriction enzymes?
A. degrading the DNA molecule
B. Cutting Fragments of DNA into nucleotides
C. Restricting the growth of bacteria
D. Cutting DNA at specific nucleotide sequences
E. Prevents the formation of the sugar-phosphate backbone
D. Cutting DNA at specific nucleotide sequences
What is the significance of the annealing temperature in a PCR reaction? A. degrading primers B. elongation of DNA strands C. binding of primers D. separation of the DNA strands E. denaturation of Taq DNA polymerase
C. binding of primers
Glucosyl-transferase identifies what? A. Misfolded sequences B. Correctly folded proteins C. NH2 groups on proteins D. Hydrophilic amino acids
A. misfolded sequences
What is the function of the leader sequence?
A. targeting to peroxisomes
B. targeting of nuclear proteins
C. targeting of proteins to mitochondria
D. limiting cytoplasmic proteins to specific regions
E. coupling of ribosomes to ER
E. coupling of ribosomes to ER
A lysosomal protein has its leader sequence cleaved in ER, where does it end up? A. plasma membrance B. lysosome C. peroxisome D. nucleus E. ER
B. lysosome
What is the function of DNA polymerase? A. ligation of DNA strands B. stabilizing single-stranded DNA C. removes primers D. adding nucleotides E. relaxing the double helix
D. adding nucleotides
Which technique do we use to separate DNA molecules on the basis of size? A. PCR B. Gel electrophoresis C. DNA sequencing D. DNA probing E. Hybridization
B. Gel electrophoresis
What are proto-oncogenes? A. genes involved in cell death B. genes that restrict growth C. genes involved in normal cell function and regulation D. activated genes E. cancer-causing genes
C. genes involved in normal cell function and regulation
Where are proteins targeted if they have mannose-6-phosphate? A. mitochondria B. peroxisomes C. lysosome D. plasma membrane E. cytoplasm
C. lysosome
If an antibiotic binds to the 30s subunit, what will be inhibited? A. elongation B. initiation C. translocation D. termination E. mRNA reading
B. initiation
What is a structural feature of collagen? A. heavily hydroxylated B. beta sheets C. made of tetrapeptide repeats D. rich in phenylalanine
A. heavily hydroxylated
What nucleotide modification is involved in the regulation of large chromosome regions? A. methylation B. lipidation C. hydroxylation D. oligomerization E. glycosylation
A. methylation
What is the difference between HbS and HbA? A. S-S bonds B. Covalent linkage C. Ionic attractions D. Primary structure E. Hydrogen bonds
D. Primary structure
Relating temperature to enzyme activity, what is the reason behind decreased enzyme activity at higher temperatures? A. Denaturation B. Decreased ΔG C. Substrates degrade D. Decreased activation energy
A. Denaturation
What is the effect of an allosteric effector on an enzyme?
A. interacting with the active site covalently
B. changing the protein configuration
C. always decreases enzyme activity
D. regulating enzyme activity reversibly via the active site
E. always increases enzyme activity
B. changing the protein configuration
Which is most probably used to regulate a metabolic pathway?
A. regulating the first step that ends in the product
B. regulation of a step that branches
C. allosteric regulation of the fastest step in the pathway
D. regulating the step with ΔG=0
E. regulating the final step leading to the formation of the product
A. regulating the first step that ends in the product
What is a feature of 5’ capping?
A. the cap is added is a 5’-3’ direction
B. it is catalyzed by RNA polymerase II
C. It is made of a 7-methylguanosine
D. The cap is added after polyadenylation and splicing
E. It is added to the 20th nucleotide in the mRNA
C. It is made of a 7-methylguanosine
What is a characteristic of hemophilia A?
A. mutation is the immunosuppressive factor VIII
B. deficiency in the immunosuppressive factor VIII
C. excess of blood clotting factor VIII
D. platelet abnormalities
E. prolonged bleeding
E. prolonged bleeding
In cystic fibrosis, which ion is transported by the transmembrane regulator protein? A. K+ B. Na+ C. Cl- D. Ca++ E. Mg+
C. Cl-
If one parent is normal and one is a carrier of cystic fibrosis, what is the % of children that will have cystic fibrosis? A. 0% B. 25% C. 50% D. 75% E. 100%
A. 0%
autosomal recessive trait
What is the difference between the infectious prion protein and the normal prion protein in Creutzfeldt-Jakob disease? A. increased alpha helices B. disrupted covalent linkages C. S-S bonding deficient D. Increased beta sheets E. Ionic bonds
D. Increased beta sheets
What is the substrate that is used by glycogen synthase to synthesize glycogen? A. UTP-glucose B. UDP-glucose C. Glucose-6-phosphate D. Glucose-1-phosphate E. D-glucose
B. UDP-glucose
What is the difference between eukaryotic and prokaryotic translation?
A. using less energy
B. searching for the start codon in initiation
C. using less initiation factors
D. Tu delivers charged t-RNA
E. Smaller ribosomes
B. searching for the start codon in initiation
At what level does interferon regulation of gene expression occur? A. transcription initiation B. transcription termination C. polyadenylation and splicing D. mRNA stability E. global regulation
A. transcription initiation
Why isn’t DNA synthesis in DNA sequencing PCR geometric?
A. two primers used
B. one primer used
C. higher annealing temperature
D. half the number of initial strands used
E. because of using a slower polymerase
B. one primer used
What characterizes RNA polymerase I? A. not sensitive to α-amanitin B. catalyzes t-RNA synthesis C. has a proofreading activity D. uses dNTP’s E. catalyzes mRNA synthesis
A. not sensitive to α-amanitin
A defect in which repair system leads to HNPCC? A. base excision repair B. nucleotide excision repair C. 3’-5’ exonuclease activity D. DNA mismatch repair E. Dimer repair
D. DNA mismatch repair
HNPCC= Hereditary nonpolyposis colorectal cancer
What group in ddNTP is responsible for termination in a PCR reaction? A. 1’OH B. 2’H C. 3’H D. 4’OH E. 5’OH
C. 3’H
What are ribozymes? A. splicing RNA B. ribosome forming RNA C. catalytic RNA D. amino acid carrying RNA E. Protein synthesizing RNA
C. catalytic RNA
What do chaperones bind to in a protein to assist in folding? A. buried hydrophobic amino acids B. exposed hydrophilic amino acids C. basic amino acids D. buried hydrophilic amino acids E. exposed hydrophobic amino acids
E. exposed hydrophobic amino acids
An enzyme is stored as an inactive precursor. It is activated irreversibly by cleavage of a section of the polypeptide. What is this mechanism of activation called? A. allostery B. cooperativity C. covalent activation D. proteolysis
D. proteolysis
What is the function of the BCR-ABL protein? A. Serine-threonine kinase B. tyrosine kinase C. transcription factor D. protein folding E. apoptosis regulation
B. tyrosine kinase
