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Quick Biochemistry - Nucleic Acids (Section 3)

1
In which direction does genetic information typically proceed?
Answer
(B)
From DNA to RNA
2
What best describes the genetic code?
Answer
(A)
A collection of codons
3
What is a consequence of the degeneracy of the genetic code?
Answer
(B)
Multiple codons can specify the same amino acids
4
Regarding the genetic code, which statement is generally accepted?
Answer
(B)
It is non-overlapping
5
To what nucleotide sequence is mRNA the complement?
Answer
(A)
Coding strand
6
During DNA replication, which enzyme is essential at the initial stage?
Answer
(B)
Unwinding proteins
7
What is the smallest DNA unit capable of directing polypeptide synthesis?
Answer
(C)
Cistron
8
What element signifies the end of RNA molecule synthesis, recognized by a termination protein?
Answer
(A)
Rho (p) factor
9
Following the completion of RNA synthesis, which factor aids in the initiation of a new RNA molecule's production by recognizing a promoter?
Answer
(D)
σ factor
10
During transcription in bacterial cells, what is required?
Answer
(C)
Both the sigma unit and core enzymes of RNA polymerase are needed for accurate promoter site binding
11
Regarding RNA and DNA polymerases, which statement is accurate?
Answer
(D)
All RNA and DNA polymerases only add nucleotides at the 3' end of the growing polynucleotide chain
12
Regarding eukaryotic nuclear chromosomal DNA, which characteristic is true?
Answer
(A)
It is a linear and unbranched molecule
13
In an operon system, a repressor protein's primary function is to halt synthesis by attaching to
Answer
(B)
A specific region of the operon, preventing structural gene transcription
14
Which sequence is the most common variation found in pribnow boxes?
Answer
(A)
5'-TATAAT-3'
15
The 5' end of an mRNA molecule typically has which of the following attached?
Answer
(B)
7-Methylguanosine triphosphate
16
What is the first codon to be translated on an mRNA strand?
Answer
(A)
AUG
17
The codon AUG, which codes for methionine, is significant because it serves as a
Answer
(D)
A chain initiating codon
18
During protein biosynthesis, which codons signal the termination of the polypeptide chain?
Answer
(A)
UAA, UAG and UGA
19
The formation of an initiation complex during protein synthesis necessitates which factor?
Answer
(A)
IF-III
20
During protein synthesis in E. coli, what amino acid residue typically tags the amino terminal of all polypeptide chains initially?
Answer
(C)
N-formyl methinine
21
Protein synthesis starts when what attaches?
Answer
(A)
40S ribosome unit to mRNA
22
The beginning of protein synthesis needs what molecule?
Answer
(D)
GTP
23
Which enzyme helps add the correct amino acid to a tRNA?
Answer
(B)
tRNA loading with amino acids
24
How many high-energy phosphate bonds are used to prepare amino acids for protein building?
Answer
(C)
Two
25
What is the final product of translation?
Answer
(A)
Protein
26
During chain elongation, what is needed for an aminoacyl tRNA to bind to the A site?
Answer
(A)
Correct codon recognition
27
What molecule is needed for the new aminoacyl tRNA to enter the A site?
Answer
(D)
EF-I
28
Which enzyme helps a new amino acid attach to the existing chain?
Answer
(C)
Peptidyl transferase
29
When a new amino acid joins the chain, how many ATP molecules are used?
Answer
(A)
Zero
30
What molecules are needed for the peptidyl tRNA to move from the A site to the P site?
Answer
(A)
EF-II, GTP
31
Within eukaryotic cells, which statement is accurate regarding translation?
Answer
(B)
Cyclohexamide interferes with the elongation phase of translation
32
Amanitin, a toxin found in certain mushrooms, inhibits
Answer
(B)
mRNA production
33
Tetracylin disrupts polypeptide synthesis by
Answer
(D)
Preventing aminoacyl tRNA from binding
34
In prokaryotic cells, the effect of chloramphenicol is
Answer
(A)
To prematurely release the polypeptide chain
35
Streptomycin's impact on polypeptide synthesis involves
Answer
(A)
Halting the initiation stage
36
Erythromycin targets ribosomes and prevents
Answer
(D)
Translocation
37
The interaction of prokaryotic DNA-dependent RNA polymerase with gene promoter sites is blocked by which antibiotic?
Answer
(B)
Rifamycin
38
During gene repression, which gene is transcribed?
Answer
(B)
Regulatory gene
39
In the lac operon, which gene exhibits continuous expression?
Answer
(A)
i
40
What is the smallest functional size of an operator needed for lac repressor binding?
Answer
(D)
17 base pairs
41
For structural gene transcription initiation, which region must be accessible in lac operation?
Answer
(B)
Operator locus
42
In the lac operon model, what is the function of a protein molecule?
Answer
(D)
Repressor
43
Catabolite repression is facilitated by a catabolite gene activator protein (CAP) combined with
Answer
(C)
cAMP
44
What is the primary function of the enzyme DNA ligase?
Answer
(B)
Connects the end of two DNA chains
45
What is the primary function of restriction endonucleases?
Answer
(D)
Act as defensive enzymes to protect the host bacterial DNA from DNA of foreign organisms
46
Which type of mutation is most likely to be lethal?
Answer
(B)
Insertion of one nucleotide
47
In a partial mRNA sequence, a mutation in the template DNA alters codon 91 to UAA. What kind of mutation is this?
Answer
(B)
Silent
48
Restriction endonucleases identify and cleave a particular sequence of
Answer
(B)
Double stranded DNA
49
Positive control of induction is best defined as a control system where an operon operates
Answer
(D)
Only after an inducer protein, which is activated by an inducer, switch it on
50
What describes the nature of Interferon?
Answer
(D)
Requires expression of cellular genes