Quick Biochemistry - Nucleic Acids (Section 8)
1
Which type of tRNA initiates translation in eukaryotic cells?
2
Which tRNA starts translation in prokaryotic cells?
3
In eukaryotic cells, which initiation factor is NOT a part of the 40S pre-initiation complex?
4
To which cellular component do the eukaryotic initiation factors 4A, 4B, and 4F bind?
5
What is the specific codon that signals the start of translation?
6
In association with which factor(s) does the initial amino acyl tRNA approach the 40 S ribosomal subunit?
7
What is the primary function of elF-1A and elF-3?
پاسخ دهید(D)
To prevent binding of 60 S subunit to 40 S subunit
8
Which enzymatic activity is associated with elF-4 A?
9
What is the primary function of elF-4 B?
پاسخ دهید(D)
Unwinds mRNA near its 5' end
10
Where is peptidyl transferase activity found?
11
Following the creation of a peptide bond, what is responsible for moving mRNA along the ribosome?
12
Which of the following substances prevents formylmethionyl tRNA from attaching to the 30S ribosomal subunit in prokaryotes?
13
What is the effect of tetracyclines on the binding of amino acyl tRNAs?
14
Which substance interferes with the peptidyl transferase function of 50S ribosomal subunits?
15
What is the effect of erythromycin's binding to the 50S ribosomal subunit?
16
In which type of cell does puromycin trigger early chain termination?
17
Which process is disrupted by diphtheria toxin?
18
Which of the following is NOT a characteristic of proteins that are secreted from a cell?
پاسخ دهید(D)
They are tagged with ubiquitin
19
Where are the SRP receptors involved in protein export located?
20
At what point is the signal sequence removed from proteins?
پاسخ دهید(B)
In the endoplasmic reticulum
21
What determines how long a protein lasts?
22
In addition to the protein-coding genes, what other sequences are found in DNA that control gene regulation?
23
What are inducers and repressors classified as?
24
Which of the following is a cis-acting element?
25
What is the main function of silencer elements?
پاسخ دهید(C)
Decrease the expression of some structural genes
26
Which of the following are examples of trans-acting factors?
27
Which of the following is NOT a characteristic of enhancer elements?
پاسخ دهید(B)
Each enhancer activates a specific promoter
28
What might cause the dihydrofolate reductase gene to be amplified?
29
What structural motif is commonly found in proteins that influence transcription by interacting with DNA?
30
Where is the Lac operon, a collection of genes, found?
31
What is the composition of the lac operon?
پاسخ دهید(D)
A regulatory gene, an operator, a promoter and three structural genes
32
The regulatory i gene of the lac operon performs which function?
33
Where does the RNA polymerase holoenzyme bind within the lac operon?
34
Which factor prevents the transcription of the z, y, and a genes in the lac operon?
35
What prevents the transcription of the structural genes in the lac operon through the binding of the repressor tetramer?
36
The enzymes produced by the z, y, and a genes of the lac operon are activated by which substance?
37
What promotes the binding of RNA polymerase holoenzyme to the promoter region of the lac operon?
38
How do lactose and its analogs positively regulate the lac operon?
پاسخ دهید(D)
Binding to repressor subunits so that the repressor cannot attach to the operator locus
39
Which of the following does NOT affect the expression of structural genes in the lac operon?
40
Which components are coded for in the lac operon's coding sequences?
41
What is a potential cause of genetic alterations?
42
What compound is capable of inducing mutations?
43
What is the effect of nitrosamine on a specific DNA base?
44
Which alteration can occur in DNA due to ultraviolet radiation exposure?
45
How can DNA damage caused by ultraviolet radiation be fixed?
46
What is the underlying defect in Xeroderma pigmentosum?
47
Which of the following does NOT accurately describe Xeroderma pigmentosum?
پاسخ دهید(B)
Its inheritance is autosomal dominant
48
What type of mutation involves replacing adenine with guanine in DNA?
49
What type of mutation involves replacing thymine with adenine in DNA?
50
What describes a point mutation's origin?
