MCQOPTIONS
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MCQOPTIONS
This section includes 32 Mcqs, each offering curated multiple-choice questions to sharpen your Biochemistry knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Transcription by polymerase occurs in |
| A. | four phases known as initiation, propagation, elongation and termination |
| B. | three phases known as initiation, elongation and termination |
| C. | two phases known as initiation and termination |
| D. | none of the above |
| Answer» C. two phases known as initiation and termination | |
| 2. |
Rho-dependent termination of transcription in |
| A. | requires ATP |
| B. | requires about 50 nucleotides of uncomplexed mRNA |
| C. | both (a) and (b) |
| D. | removes mRNA and holoenzyme from the DNA |
| Answer» D. removes mRNA and holoenzyme from the DNA | |
| 3. |
Which of the following conditions would cause the release of the lac repressor protein from the lac operator site on DNA? |
| A. | Presence of glucose in the growth media |
| B. | Presence of lactose in the growth media |
| C. | Presence of IPTG (isopropyl thiogalactoside) in the growth media |
| D. | Both (b) and (c) |
| Answer» E. | |
| 4. |
In eukaryotes, there are three different RNA polymerases. The RNA polymerase responsible for transcription of mRNA is |
| A. | RNA polymerase I |
| B. | RNA polymerase II |
| C. | RNA polymerase III |
| D. | none of these |
| Answer» C. RNA polymerase III | |
| 5. |
The nucleons of eukaryotic cell has |
| A. | RNA polymerase I |
| B. | RNA polymerase II |
| C. | RNA polymerase III |
| D. | all of these |
| Answer» E. | |
| 6. |
Upstream regions which are essential for correct transcription are called |
| A. | enhancers |
| B. | start codons |
| C. | promoters |
| D. | transcription factors |
| Answer» D. transcription factors | |
| 7. |
Transcription begins |
| A. | at the start codon |
| B. | upstream from the start codon |
| C. | downstream from the start codon |
| D. | none of these |
| Answer» C. downstream from the start codon | |
| 8. |
Most transcripts of protein coding genes are cleaved |
| A. | at the 3' end just after a poly adenylation signal |
| B. | at the 3' end just before a poly adenylation signal |
| C. | at the 5' end immediately after a poly adenylation signal |
| D. | at the 5' end immediately before a poly adenylation signal |
| Answer» B. at the 3' end just before a poly adenylation signal | |
| 9. |
The function of the sigma factor of RNA polymerase is to |
| A. | assure that transcription begins at the proper point |
| B. | assure that transcription ends at the proper point |
| C. | assure that translation begins at the proper point |
| D. | assure that translation ends at the proper point |
| Answer» B. assure that transcription ends at the proper point | |
| 10. |
Transcription results in |
| A. | an amino acid chain |
| B. | messenger RNA |
| C. | complementary DNA |
| D. | Okazaki fragments |
| Answer» C. complementary DNA | |
| 11. |
RNA polymerase holoenzyme initiates transcription which involves |
| A. | recognition of the -10 sequence and -35 sequence |
| B. | recognition of the -10 sequence only |
| C. | recognition of the -35 sequence only |
| D. | none of the above |
| Answer» B. recognition of the -10 sequence only | |
| 12. |
In prokaryotes, transcription is |
| A. | terminated by the stop codon |
| B. | terminated by a protein called rho |
| C. | terminated by a poly A sequence |
| D. | terminated by a start codon |
| Answer» C. terminated by a poly A sequence | |
| 13. |
The major function of RNA polymerase's sigma factor is |
| A. | recognition of the translational stop sequence |
| B. | recognition of the transcriptional start sequence |
| C. | recognition of the transcriptional stop sequence |
| D. | recognition of the translational start sequence |
| Answer» C. recognition of the transcriptional stop sequence | |
| 14. |
What is a promoter? |
| A. | A specific sequence of DNA to which a catabolic repressor binds |
| B. | A specific sequence of DNA to which RNA polymerase binds |
| C. | A specific DNA sequence to which a restriction endonuclease binds |
| D. | None of the above |
| Answer» C. A specific DNA sequence to which a restriction endonuclease binds | |
| 15. |
In both eukaryotes and prokaryotes, a promoter region that is rich in AT bases is called as |
| A. | CATT |
| B. | Shine Dalgarno region |
| C. | TATA box |
| D. | SV40 region |
| Answer» D. SV40 region | |
| 16. |
The RNA polymerases that transcribe bacterial DNA are |
| A. | multisubunit enzymes |
| B. | only active inside the cell |
| C. | interchangable with DNA polymerases |
| D. | highly glycosylated in their active forms |
| Answer» B. only active inside the cell | |
| 17. |
Immediately after transcription |
| A. | a methylated guanine cap is added to the 51 end of the transcript |
| B. | a methylated guanine cap is added to the 31 end of the transcript |
| C. | both (a) and (b) |
| D. | a poly adenylation signal is added |
| Answer» B. a methylated guanine cap is added to the 31 end of the transcript | |
| 18. |
Transcription by E. coli polymerase occurs in |
| A. | four phases known as initiation, propagation, elongation and termination |
| B. | three phases known as initiation, elongation and termination |
| C. | two phases known as initiation and termination |
| D. | none of the above |
| Answer» C. two phases known as initiation and termination | |
| 19. |
Which of the following is necessary for transcription to occur? |
| A. | DNA molecule |
| B. | RNA polymerase |
| C. | DNA polymerase |
| D. | Both DNA & RNA polymerase |
| Answer» E. | |
| 20. |
Multiple copies of 5S genes, located at a chromosomal site distinct from the other rRNA genes |
| A. | are transcribed by rRNA polymerase III and the 5S rRNA |
| B. | are transcribed by rRNA polymerase II |
| C. | are transcribed by rRNA polymerase I and the 5S rRNA |
| D. | are transcribed by DNA polymerase I |
| Answer» B. are transcribed by rRNA polymerase II | |
| 21. |
Each tRNA molecule has a cloverleaf secondary structure consisting of |
| A. | three stem loops |
| B. | two stem loops |
| C. | four stem loops |
| D. | either (a) or (b) |
| Answer» B. two stem loops | |
| 22. |
The closed complex at bacterial promoters is |
| A. | in equilibrium with free RNA polymerase and the promoter |
| B. | not affected by promoter mutations |
| C. | bound more tightly when repressors are present |
| D. | not affected by activator proteins |
| Answer» B. not affected by promoter mutations | |
| 23. |
The regions of a gene located at -10 and -35, with respect to the start of transcription, are termed |
| A. | start codons. |
| B. | oriC regions. |
| C. | Shine Dalgarno sequences. |
| D. | promoters. |
| Answer» E. | |
| 24. |
RNA polymerase in prokaryotes has a removable |
| A. | alpha subunit |
| B. | beta subunit |
| C. | both (a) and (b) |
| D. | sigma subunit |
| Answer» E. | |
| 25. |
Promoters for tRNAs are located |
| A. | upstream from the start codon |
| B. | downstream from the start codon |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» C. both (a) and (b) | |
| 26. |
Rho-dependent termination of transcription in E. coli |
| A. | requires ATP |
| B. | requires about 50 nucleotides of uncomplexed mRNA |
| C. | both (a) and (b) |
| D. | removes mRNA and holoenzyme from the DNA |
| Answer» D. removes mRNA and holoenzyme from the DNA | |
| 27. |
The transcriptional regulatory proteins in eukaryotes which induce transcription usually have |
| A. | at least two distinct domains of protein structure, a DNA binding domain and an activation domain |
| B. | at least two distinct domains of protein structure and a DNA binding domain |
| C. | at least one distinct domains of protein structure, a DNA binding domain and an activation domain |
| D. | none of these |
| Answer» B. at least two distinct domains of protein structure and a DNA binding domain | |
| 28. |
RNA is synthesized on a DNA template in a process called __________ , which utilizes the enzyme __________ |
| A. | translation, RNA polymerase |
| B. | transcription, DNA polymerase |
| C. | transcription, RNA polymerase |
| D. | replication, DNA polymerase |
| Answer» D. replication, DNA polymerase | |
| 29. |
The binding of lac repressor to DNA could be considered to be analogous to |
| A. | competitive inhibition of an enzyme |
| B. | mixed-type inhibition of an enzyme |
| C. | uncompetitive inhibition of an enzyme |
| D. | allosteric effects in enzyme regulation |
| Answer» B. mixed-type inhibition of an enzyme | |
| 30. |
The complex of RNA polymerase, DNA template and new RNA transcript is called |
| A. | transcription bubble |
| B. | replication bubble |
| C. | a translation bubble |
| D. | none of these |
| Answer» B. replication bubble | |
| 31. |
Enhancers are regions that |
| A. | bind RNA polymerase |
| B. | are adjacent to the TATA box |
| C. | are CAT box binding proteins |
| D. | modulate transcription |
| Answer» E. | |
| 32. |
Transcription of each set of rRNA genes by RNA polymerasel produces |
| A. | a single 45S rRNA precursor molecule |
| B. | a single 5S rRNA precursor molecule |
| C. | a single 18S rRNA precursor molecule |
| D. | a single 28S rRNA precursor molecule |
| Answer» B. a single 5S rRNA precursor molecule | |