Lecture 7: DNA Transcription

Question 1

Which of the following correctly describes a difference between DNA and RNA?
a) RNA contains thymine instead of uracil.
b) RNA has deoxyribose sugar, while DNA has ribose sugar.
c) RNA has uracil instead of thymine, and DNA has deoxyribose instead of ribose.
d) DNA contains a hydroxyl group at the 2’ position, while RNA has a hydrogen.

Answer 1

Answer: c) RNA has uracil instead of thymine, and DNA has deoxyribose instead of ribose.

Question 2

During transcription in bacteria, the sigma factor:
a) Synthesizes RNA from DNA.
b) Provides energy for phosphodiester bond formation.
c) Helps RNA polymerase recognize the promoter sequence.
d) Cleaves the DNA strands.

Answer 2

Answer: c) Helps RNA polymerase recognize the promoter sequence.

Question 3

Arrange the RNA types by their abundance in a cell (from most to least):
a) tRNA, rRNA, mRNA
b) rRNA, tRNA, mRNA
c) mRNA, rRNA, tRNA
d) rRNA, mRNA, tRNA

Answer 3

Answer: b) rRNA, tRNA, mRNA

Question 4

Which of the following is FALSE about bacterial transcription?
a) Initiation of transcription occurs at the ATG start codon.
b) Promoters are regulatory DNA sequences found upstream of genes.
c) Different sigma factors allow transcription of different genes.
d) Efficiency of RNA synthesis increases in the elongation phase compared to initiation.

Answer 4

Answer: a) Initiation of transcription occurs at the ATG start codon.

Question 5

What is the primary function of the TATA-binding protein (TBP) in transcription initiation?
a) To unwind the DNA double helix.
b) To phosphorylate RNA polymerase II.
c) To recognize and bind the TATA box in the promoter region.
d) To synthesize RNA from a DNA template.

Answer 5

Answer: c) To recognize and bind the TATA box in the promoter region.

Question 6

Problem: Given the DNA template strand:
5’…GCATCACTTC…3’

What is the sequence of the transcribed RNA?

Answer 6

Answer: RNA sequence: 5’…CGUAGUGGAAG…3’

Question 7

Problem: If the promoter sequence is located on the bottom strand of a DNA segment, and transcription proceeds in the 5’ to 3’ direction, which strand is used as the template?

Answer 7

Answer: The top strand will be the template strand.

Question 8

Problem: You are designing an experiment to test RNA synthesis using reverse transcriptase. Which type of RNA would you convert to cDNA for sequencing the spike protein?

Answer 8

Answer: mRNA.

Question 9

Problem: If a protein synthesis starts at the N-terminus, which direction does the ribosome move along the mRNA?

Answer 9

Answer: 5’ to 3’.

Question 10

Problem: Describe how the termination of transcription is signaled in bacterial cells.

Answer 10

Answer: The RNA forms a hairpin loop structure by folding back on itself due to complementary base pairing, which signals the RNA polymerase to stop transcription.

Question 11

Which of the following is NOT part of the central dogma of molecular biology?
a) DNA replication
b) RNA transcription
c) Protein synthesis
d) RNA to DNA synthesis

Answer 11

Answer: d) RNA to DNA synthesis

Question 12

What is the role of reverse transcriptase?
a) To convert DNA into RNA
b) To convert RNA into DNA
c) To sequence DNA for proteins
d) To store genetic information permanently

Answer 12

Answer: b) To convert RNA into DNA

Question 13

Why is reverse transcriptase used in RT-PCR?
a) To amplify DNA directly from cells
b) To create cDNA from RNA for further analysis
c) To degrade RNA after protein synthesis
d) To enhance the stability of RNA molecules

Answer 13

Answer: b) To create cDNA from RNA for further analysis

Question 14

Which statement best describes the function of DNA in cells?
a) DNA acts as transient storage for genetic information.
b) DNA permanently stores genetic information.
c) DNA is synthesized from RNA.
d) DNA is primarily used for catalytic functions.

Answer 14

Answer: b) DNA permanently stores genetic information.

Question 15

RNA is referred to as “transient storage” because:
a) It is used for long-term storage of genetic information.
b) It temporarily holds genetic information needed for protein synthesis.
c) It is resistant to degradation compared to DNA.
d) It serves as a catalyst in DNA replication.

Answer 15

Answer: b) It temporarily holds genetic information needed for protein synthesis.

Question 16

In protein synthesis, mRNA is:
a) Stored in the nucleus for long-term use.
b) Transported to ribosomes for translation into protein.
c) Converted directly into DNA.
d) Broken down immediately after transcription.

Answer 16

Answer: b) Transported to ribosomes for translation into protein.

Question 17

Why is mRNA often degraded after protein synthesis?
a) To prevent the production of excess proteins.
b) Because it is a permanent storage molecule.
c) To ensure long-term genetic stability.
d) To convert back into DNA.

Answer 17

Answer: a) To prevent the production of excess proteins.

Question 18

Which of the following applications uses reverse transcriptase?
a) DNA fingerprinting
b) Reverse transcription PCR (RT-PCR)
c) Genome editing with CRISPR
d) Protein synthesis in ribosomes

Answer 18

Answer: b) Reverse transcription PCR (RT-PCR)

Question 19

During transcription, RNA is:
a) Complementary to the coding strand of DNA.
b) Complementary to the template strand of DNA.
c) Identical to the template strand, except “T” is replaced with “U.”
d) Identical to the coding strand, including “T.”

Answer 19

Answer: b) Complementary to the template strand of DNA.

Question 20

What is a key structural difference between RNA and DNA?
a) RNA contains thymine, while DNA contains uracil.
b) DNA has ribose, while RNA has deoxyribose.
c) RNA contains ribose, which has a hydroxyl group at the 2’ position.
d) DNA is more reactive than RNA due to the hydroxyl group in its sugar.

Answer 20

Answer: c) RNA contains ribose, which has a hydroxyl group at the 2’ position.

Question 21

Why is RNA more reactive and less stable than DNA?
a) RNA contains uracil instead of thymine.
b) RNA lacks the 3’ hydroxyl group needed for stability.
c) RNA has an extra hydroxyl group at the 2’ position of its sugar.
d) RNA is single-stranded, while DNA is double-stranded.

Answer 21

Answer: c) RNA has an extra hydroxyl group at the 2’ position of its sugar.

Question 22

What is true about the RNA sequence relative to the coding strand of DNA?
a) RNA is complementary to the coding strand.
b) RNA has the same sequence as the coding strand, except “T” is replaced with “U.”
c) RNA has the same sequence as the coding strand, including “T.”
d) RNA is identical to the template strand of DNA.

Answer 22

Answer: b) RNA has the same sequence as the coding strand, except “T” is replaced with “U.”

Question 23

What is required for forming phosphodiester bonds during RNA elongation?
a) The presence of uracil in the template strand.
b) The 2’ hydroxyl group in ribose.
c) The 3’ hydroxyl group in ribose.
d) The removal of thymine from the RNA sequence.

Answer 23

Answer: c) The 3’ hydroxyl group in ribose.

Question 24

What is the primary function of mRNA?
a) Catalyzing peptide bond formation
b) Storing genetic information permanently
c) Coding for proteins
d) Splicing introns from pre-mRNA

Answer 24

Answer: c) Coding for proteins

Question 25

What is the role of ribosomal RNA (rRNA) in cells? a) Coding for proteins b) Catalyzing peptide bond formation and forming ribosome structure c) Transporting amino acids to ribosomes d) Regulating gene expression

Answer 25

Answer: b) Catalyzing peptide bond formation and forming ribosome structure

Question 26

Transfer RNA (tRNA) plays what role in protein synthesis? a) Synthesizing ribosomes b) Translating mRNA codons into amino acids c) Splicing pre-mRNA d) Binding to ribosomal subunits

Answer 26

Answer: b) Translating mRNA codons into amino acids

Question 27

Small nuclear RNAs (snRNAs) are involved in: a) Protein synthesis b) Splicing and modifying pre-mRNA c) Transporting mRNA to the ribosome d) Catalyzing tRNA binding

Answer 27

Answer: b) Splicing and modifying pre-mRNA

Question 28

Small interfering RNAs (siRNAs): a) Bind to ribosomes to catalyze protein synthesis b) Regulate gene expression by degrading mRNA or establishing chromatin structures c) Form ribosome subunits d) Facilitate DNA replication

Answer 28

Answer: b) Regulate gene expression by degrading mRNA or establishing chromatin structures

Question 29

What percentage of total RNA in a cell is ribosomal RNA (rRNA)? a) 3–5% b) 10–15% c) 75–80% d) Less than 5%

Answer 29

Answer: c) 75–80%

Question 30

Which RNA type makes up less than 5% of total RNA in a cell? a) tRNA b) rRNA c) mRNA d) lncRNA

Answer 30

Answer: d) lncRNA

Question 31

What is the primary function of piwi-interacting RNA (piRNA)? a) Synthesizing ribosomal proteins b) Regulating gene expression through mRNA degradation c) Protecting germ line cells from transposable elements d) Acting as adaptors between mRNA and amino acids

Answer 31

Answer: c) Protecting germ line cells from transposable elements

Question 32

Telomerase RNA (TERC) functions as: a) A catalyst for DNA replication at chromosome ends b) A template for extending chromosome ends c) A component of ribosomes d) A regulator of mRNA degradation

Answer 32

Answer: b) A template for extending chromosome ends

Question 33

Which RNA type is known for having structural and regulatory roles, but not for encoding proteins? a) rRNA b) tRNA c) lncRNA d) snRNA

Answer 33

Answer: c) lncRNA

Question 34

The RNA transcribed from the template strand of DNA: a) Is identical to the template strand except for "U" replacing "T." b) Is complementary to the template strand and has "U" instead of "T." c) Has the same sequence as the template strand, including "T." d) Has "U" instead of "T" but is identical to the coding strand.

Answer 34

Answer: b) Is complementary to the template strand and has "U" instead of "T."

Question 35

RNA is less stable than DNA because: a) It contains uracil instead of thymine. b) It has an extra hydroxyl group at the 2’ position of ribose. c) It forms double-stranded helices. d) It has a deoxyribose sugar.

Answer 35

Answer: b) It has an extra hydroxyl group at the 2’ position of ribose.

Question 36

The most abundant RNA type in cells is: a) mRNA b) rRNA c) tRNA d) siRNA

Answer 36

Answer: b) rRNA

Question 37

What is the primary role of RNA polymerase? a) To synthesize DNA from RNA templates. b) To synthesize RNA from DNA templates. c) To replicate DNA. d) To repair DNA strands.

Answer 37

Answer: b) To synthesize RNA from DNA templates.

Question 38

Which statement best describes the primer requirement for RNA polymerase? a) RNA polymerase requires an RNA primer to initiate synthesis. b) RNA polymerase does not require a primer to initiate synthesis. c) RNA polymerase requires a DNA primer for transcription. d) RNA polymerase uses ribozymes as primers.

Answer 38

Answer: b) RNA polymerase does not require a primer to initiate synthesis.

Question 39

Which polymerase has a more efficient proofreading mechanism? a) RNA polymerase b) DNA polymerase c) Both have equal proofreading efficiency. d) Neither has a proofreading mechanism.

Answer 39

Answer: b) DNA polymerase

Question 40

RNA polymerase has an error rate of approximately: a) 1 in 10⁴ rNTPs incorporated b) 1 in 10⁷ rNTPs incorporated c) 1 in 10⁹ rNTPs incorporated d) No measurable error rate

Answer 40

Answer: a) 1 in 10⁴ rNTPs incorporated

Question 41

RNA polymerase uses __________ as substrates to catalyze the formation of phosphodiester bonds. a) Deoxyribonucleotides (dNTPs) b) Ribonucleotides (rNTPs) c) Both dNTPs and rNTPs d) None of the above

Answer 41

Answer: b) Ribonucleotides (rNTPs)

Question 42

DNA polymerase requires which of the following to initiate synthesis? a) A pre-existing primer (either DNA or RNA) b) A promoter region on the DNA template c) A ribonucleotide sequence d) No primer is required

Answer 42

Answer: a) A pre-existing primer (either DNA or RNA)

Question 43

Both RNA polymerase and DNA polymerase synthesize nucleic acids in which direction? a) 3’ to 5’ b) 5’ to 3’ c) Both directions simultaneously d) Direction depends on the template strand orientation

Answer 43

Answer: b) 5’ to 3’

Question 44

How does the error rate of DNA polymerase compare to that of RNA polymerase? a) DNA polymerase has a higher error rate. b) RNA polymerase has a higher error rate. c) Both have the same error rate. d) RNA polymerase has no error rate.

Answer 44

Answer: b) RNA polymerase has a higher error rate.

Question 45

RNA polymerase and DNA polymerase both catalyze the formation of which type of bond? a) Hydrogen bonds between bases b) Phosphodiester bonds between nucleotides c) Peptide bonds between amino acids d) Glycosidic bonds in sugars

Answer 45

Answer: b) Phosphodiester bonds between nucleotides

Question 46

What is the primary role of DNA polymerase? a) To repair RNA during transcription b) To replicate DNA during cell division c) To synthesize proteins from DNA templates d) To degrade incorrect RNA sequences

Answer 46

Answer: b) To replicate DNA during cell division

Question 47

What is the role of the sigma (σ) factor in RNA polymerase? a) Synthesizing ribonucleotides. b) Recognizing promoter sequences in DNA. c) Unwinding double-stranded DNA. d) Rewinding DNA after transcription.

Answer 47

Answer: b) Recognizing promoter sequences in DNA.

Question 48

In E. coli, RNA polymerase is made up of: a) Four subunits and two sigma factors. b) Five subunits in the core enzyme and one sigma factor. c) Five sigma factors and no core enzyme. d) Six subunits, including the promoter.

Answer 48

Answer: b) Five subunits in the core enzyme and one sigma factor.

Question 49

The promoter sequences recognized by RNA polymerase in prokaryotes include: a) TATA box and -10 sequences. b) -10 and -35 sequences. c) TATAAT box and transcription start site.

Answer 49

d) -35 and -45 sequences. Answer: b) -10 and -35 sequences.

Question 50

During elongation, RNA polymerase performs all of the following EXCEPT: a) Synthesizing RNA complementary to the DNA template. b) Rewinding DNA behind it. c) Releasing sigma factors. d) Terminating transcription automatically.

Answer 50

Answer: d) Terminating transcription automatically.

Question 51

The holoenzyme of RNA polymerase is: a) The core enzyme without the sigma factor. b) The core enzyme plus the sigma factor. c) Only the sigma factor. d) RNA polymerase without any subunits.

Answer 51

Answer: b) The core enzyme plus the sigma factor.

Question 52

Which of the following statements about the sigma factor is NOT true? a) It binds to promoter sequences to initiate transcription. b) It remains attached throughout the transcription process. c) It forms part of the RNA polymerase holoenzyme. d) It dissociates once elongation begins.

Answer 52

Answer: b) It remains attached throughout the transcription process.

Question 53

Which of the following is NOT true about promoters in E. coli? a) They are recognized by sigma factors. b) They include the -10 and -35 sequences. c) They are transcribed into RNA. d) They determine the transcription start site.

Answer 53

Answer: c) They are transcribed into RNA.

Question 54

Which of the following is FALSE regarding RNA polymerase activity? a) It synthesizes RNA in the 5' to 3' direction. b) It catalyzes the formation of phosphodiester bonds. c) It requires a primer to initiate synthesis. d) It incorporates ribonucleotides complementary to the DNA template strand.

Answer 54

Answer: c) It requires a primer to initiate synthesis.

Question 55

Which of the following is NOT true about prokaryotic RNA polymerase? a) It has only one type of core enzyme. b) Different sigma factors allow recognition of different promoters. c) It can recognize promoters without the sigma factor. d) It synthesizes RNA complementary to the template strand.

Answer 55

Answer: c) It can recognize promoters without the sigma factor.

Question 56

Which of the following is FALSE about the RNA polymerase holoenzyme? a) It requires sigma factors to identify promoter sequences. b) It synthesizes RNA complementary to the coding strand. c) It unwinds DNA at the transcription start site. d) It releases the sigma factor after initiation.

Answer 56

Answer: b) It synthesizes RNA complementary to the coding strand.

Question 57

During the initiation phase of transcription, which event occurs first? a) Formation of the transcription bubble b) Sigma factor binds the promoter c) RNA polymerase synthesizes short abortive transcripts d) Core enzyme binds sigma factor to form the holoenzyme

Answer 57

Answer: d) Core enzyme binds sigma factor to form the holoenzyme

Question 58

What happens when the RNA polymerase holoenzyme binds the promoter? a) Transcription bubble forms b) A closed complex forms where DNA is still double-stranded c) Sigma factor is released d) RNA polymerase begins elongation

Answer 58

Answer: b) A closed complex forms where DNA is still double-stranded

Question 59

Which of the following is NOT true about the initiation phase of transcription? a) The sigma factor guides RNA polymerase to the promoter. b) The DNA double helix is unwound to form a transcription bubble. c) RNA polymerase releases the core enzyme after initiation. d) Abortive transcripts are synthesized before promoter clearance.

Answer 59

Answer: c) RNA polymerase releases the core enzyme after initiation.

Question 60

What triggers promoter clearance in the initiation phase? a) The formation of the transcription bubble b) The release of the sigma factor c) Scrunching of DNA causing tension d) Binding of ribonucleotides

Answer 60

Answer: c) Scrunching of DNA causing tension

Question 61

During elongation, what happens to the DNA behind RNA polymerase? a) It remains single-stranded. b) It is rewound into its double-helix form. c) It is degraded by nucleases. d) It forms a hairpin structure.

Answer 61

Answer: b) It is rewound into its double-helix form.

Question 62

Which of the following is TRUE about the elongation phase? a) Sigma factor is still attached to RNA polymerase. b) RNA polymerase reads the coding strand to synthesize RNA. c) RNA polymerase adds ribonucleotides complementary to the template strand. d) The transcription bubble closes completely.

Answer 62

Answer: c) RNA polymerase adds ribonucleotides complementary to the template strand.

Question 63

What signals the end of the elongation phase? a) Rebinding of the sigma factor b) The formation of a hairpin structure in the RNA c) The addition of ribonucleotides d) The rewinding of DNA behind RNA polymerase

Answer 63

Answer: b) The formation of a hairpin structure in the RNA

Question 64

What happens to the RNA polymerase core enzyme after termination? a) It dissociates from the DNA and RNA completely. b) It reassociates with a sigma factor to begin a new transcription cycle. c) It continues elongation without the sigma factor. d) It binds to the RNA for translation.

Answer 64

Answer: b) It reassociates with a sigma factor to begin a new transcription cycle.

Question 65

Which of the following is NOT part of the termination phase? a) RNA forms a hairpin loop b) RNA polymerase transcribes the termination sequence c) DNA is left single-stranded d) The RNA strand is released from RNA polymerase

Answer 65

Answer: c) DNA is left single-stranded

Question 66

Arrange the steps of bacterial transcription in order: i. Formation of the holoenzyme ii. Sigma factor release iii. Hairpin loop formation iv. Open complex formation a) i, iv, ii, iii b) iv, i, iii, ii c) i, ii, iv, iii d) iv, iii, i, ii

Answer 66

Answer: a) i, iv, ii, iii

Question 67

During the transcription cycle, when does the sigma factor dissociate? a) After the formation of the holoenzyme b) During the elongation phase c) At the end of the initiation phase d) After the termination phase

Answer 67

Answer: c) At the end of the initiation phase

Question 68

What ensures the specificity of RNA polymerase for different genes in prokaryotes? a) Different core enzymes b) Different sigma factors c) Different types of promoters d) Different ribonucleotides

Answer 68

Answer: b) Different sigma factors

Question 69

What does the 5’ untranslated region (UTR) refer to in a gene? a) The coding region of the gene. b) The region upstream of the translation start codon, not translated into protein. c) The portion of RNA containing the promoter sequences. d) The part of the gene transcribed but not part of the final RNA product.

Answer 69

Answer: b) The region upstream of the translation start codon, not translated into protein.

Question 70

Why are the transcription start and stop sites located outside the translation start and stop codons? a) To include UTRs necessary for RNA stability and translation regulation. b) To prevent the gene from being transcribed into mRNA. c) To directly code for ribosomal proteins. d) To allow RNA polymerase to bind to ribosomes.

Answer 70

Answer: a) To include UTRs necessary for RNA stability and translation regulation.

Question 71

What marks the boundaries of the coding region in a prokaryotic gene? a) Promoter and terminator. b) Transcription start and stop sites. c) Translation start (AUG) and stop codons. d) Upstream and downstream sequences.

Answer 71

Answer: c) Translation start (AUG) and stop codons.

Question 72

In translation, the N-terminus of the protein corresponds to: a) The 3’ end of the mRNA. b) The 5’ end of the mRNA. c) The transcription start site of the gene. d) The carboxyl terminus of the polypeptide.

Answer 72

Answer: b) The 5’ end of the mRNA.

Question 73

During translation, amino acids are added to: a) The N-terminus of the growing polypeptide chain. b) The C-terminus of the growing polypeptide chain. c) Both ends simultaneously. d) The ribosome itself.

Answer 73

Answer: b) The C-terminus of the growing polypeptide chain.

Question 74

What is the purpose of the transcription bubble? a) To separate ribosomes for translation. b) To expose the DNA template strand for RNA synthesis. c) To signal the termination phase of transcription. d) To rewind DNA after transcription.

Answer 74

b)To expose the DNA template strand for RNA synthesis.

Question 75

Which statement is TRUE about the elongation phase of transcription? a) RNA polymerase synthesizes DNA complementary to the RNA template strand. b) DNA ahead of RNA polymerase unwinds, while DNA behind rewinds. c) Sigma factor remains bound to RNA polymerase throughout elongation. d) The promoter sequence is transcribed into RNA.

Answer 75

Answer: b) DNA ahead of RNA polymerase unwinds, while DNA behind rewinds.

Question 76

In prokaryotic transcription, termination occurs when: a) The RNA polymerase reaches the promoter region. b) The RNA transcript forms a hairpin loop. c) The ribosome signals RNA polymerase to stop. d) The sigma factor rebinds to the RNA polymerase.

Answer 76

Answer: b) The RNA transcript forms a hairpin loop.

Question 77

Which of the following statements is FALSE about transcription in bacteria? a) Initiation of transcription occurs at the ATG start codon. b) Promoters are regulatory DNA sequences found upstream of genes. c) Different sigma factors allow transcription of specific genes. d) The elongation phase is more efficient than the initiation phase.

Answer 77

Answer: a) Initiation of transcription occurs at the ATG start codon.

Question 78

Which of the following is NOT true about the 3' untranslated region (3’ UTR)? a) It is transcribed but not translated. b) It contains signals for RNA stability and translation regulation. c) It codes for the final amino acid of the polypeptide. d) It is located downstream of the coding region.

Answer 78

Answer: c) It codes for the final amino acid of the polypeptide.

Question 79

What is the primary determinant of which DNA strand is used as the template for transcription? a) The presence of ribosomes on the DNA strand. b) The asymmetry and orientation of the promoter sequence. c) The direction of the coding sequence. d) The 3' end of the DNA strand.

Answer 79

Answer: b) The asymmetry and orientation of the promoter sequence.

Question 80

If RNA polymerase moves from 5’ to 3’ on the RNA being synthesized, which direction is the template strand being read? a) 3’ to 5’ b) 5’ to 3’ c) Both directions simultaneously d) Template strand orientation does not matter

Answer 80

Answer: a) 3’ to 5’

Question 81

The template strand of DNA is also known as: a) The sense strand. b) The coding strand. c) The antisense strand. d) The promoter strand.

Answer 81

Answer: c) The antisense strand.

Question 82

How does the orientation of the promoter influence transcription? a) It determines the length of the RNA transcript. b) It dictates which strand of DNA is used as the template and the direction RNA polymerase moves. c) It determines where the ribosome will bind. d) It controls the 3’ end of the RNA transcript.

Answer 82

Answer: b) It dictates which strand of DNA is used as the template and the direction RNA polymerase moves.

Question 83

If RNA polymerase binds to a promoter facing left to right (5’ to 3’ direction), which strand is the template strand? a) The bottom strand b) The top strand c) Both strands simultaneously d) Neither strand

Answer 83

Answer: a) The bottom strand

Question 84

What allows genes within the same DNA molecule to be transcribed using different template strands? a) Different orientations of the promoter sequence. b) The placement of stop codons. c) The simultaneous binding of RNA polymerase to both strands. d) The length of the coding region.

Answer 84

Answer: a) Different orientations of the promoter sequence.

Question 85

If Gene A uses the bottom strand as the template and Gene B uses the top strand, what explains this difference? a) The two genes have different promoter sequences with specific orientations. b) Gene B is not transcribed in the 5’ to 3’ direction. c) RNA polymerase recognizes only the coding strand. d) Gene A is longer than Gene B.

Answer 85

Answer: a) The two genes have different promoter sequences with specific orientations.

Question 86

What is indicated by the "blunt" end and "pointy" end notation on DNA diagrams? a) The 3’ end is the blunt end, and the 5’ end is the pointy end. b) The 5’ end is the blunt end, and the 3’ end is the pointy end. c) Both ends are blunt in double-stranded DNA. d) The pointy end represents the end of transcription.

Answer 86

Answer: b) The 5’ end is the blunt end, and the 3’ end is the pointy end.

Question 87

How many types of RNA polymerases are present in eukaryotes? a) 1 b) 2 c) 3 d) 5

Answer 87

Answer: c) 3

Question 88

Which RNA polymerase in eukaryotes is responsible for transcribing mRNA? a) RNA Polymerase I b) RNA Polymerase II c) RNA Polymerase III d) All of the above

Answer 88

Answer: b) RNA Polymerase II

Question 89

In prokaryotes such as E. coli, how many RNA polymerases are there? a) 1 b) 2 c) 3 d) 5

Answer 89

Answer: a) 1

Question 90

Which type of RNA polymerase is insensitive to alpha-amanitin in eukaryotes? a) RNA Polymerase I b) RNA Polymerase II c) RNA Polymerase III d) None of the above

Answer 90

Answer: a) RNA Polymerase I

Question 91

Which RNA polymerase transcribes tRNAs in eukaryotes? a) RNA Polymerase I b) RNA Polymerase II c) RNA Polymerase III d) All RNA polymerases

Answer 91

Answer: c) RNA Polymerase III

Question 92

What is the function of the pre-initiation complex (PIC) in eukaryotic transcription? a) To terminate transcription. b) To guide RNA polymerase II to the promoter. c) To transcribe mRNA directly from DNA. d) To stabilize ribosomes for protein synthesis.

Answer 92

Answer: b) To guide RNA polymerase II to the promoter.

Question 93

The TATA-binding protein (TBP) is a part of which component of the PIC? a) TFIID b) TFIIB c) TFIIH d) RNA Polymerase II

Answer 93

Answer: a) TFIID

Question 94

What is the role of TFIIH in the pre-initiation complex? a) Binding the TATA box. b) Phosphorylating the C-terminal domain of RNA Polymerase II. c) Synthesizing RNA. d) Terminating transcription.

Answer 94

Answer: b) Phosphorylating the C-terminal domain of RNA Polymerase II.

Question 95

Which of the following is NOT true about the pre-initiation complex? a) It is essential for the initiation of transcription in eukaryotes. b) It includes general transcription factors like TFIID, TFIIH, and TFIIB. c) It unwinds the DNA at the promoter region. d) It directly synthesizes RNA

Answer 95

. Answer: d) It directly synthesizes RNA.

Question 96

What is the purpose of the phosphorylation of RNA Polymerase II’s C-terminal domain (CTD) by TFIIH? a) To unwind DNA at the promoter. b) To transition RNA Polymerase II into elongation. c) To bind ribosomes for translation. d) To terminate transcription. .

Answer 96

Answer: b) To transition RNA Polymerase II into elongation

Question 97

Which general transcription factor includes helicase activity? a) TFIID b) TFIIB c) TFIIH d) TFIIE

Answer 97

Answer: c) TFIIH

Question 98

In the transcription process of eukaryotes, what is the sequence of events involving the pre-initiation complex? a) TBP binds TATA box → TFIID recruits other factors → RNA Polymerase II binds → TFIIH phosphorylates CTD b) TFIID binds TATA box → RNA Polymerase II synthesizes RNA → TFIIH terminates transcription c) TBP unwinds DNA → TFIIB releases the PIC → RNA Polymerase II binds to the ribosome d) TFIIE transcribes the gene → RNA Polymerase II terminates transcription

Answer 98

Answer: a) TBP binds TATA box → TFIID recruits other factors → RNA Polymerase II binds → TFIIH phosphorylates CTD

Question 99

Which of the following correctly describes the difference between prokaryotes and eukaryotes in terms of transcription factor requirements? a) Prokaryotes require auxiliary transcription factors, while eukaryotes do not. b) Eukaryotes require auxiliary transcription factors for RNA polymerase II to bind the promoter, while prokaryotes rely on sigma factors. c) Both prokaryotes and eukaryotes rely exclusively on sigma factors for RNA polymerase binding. d) Prokaryotes and eukaryotes both require the TATA-binding protein (TBP) for transcription initiation.

Answer 99

Answer: b) Eukaryotes require auxiliary transcription factors for RNA polymerase II to bind the promoter, while prokaryotes rely on sigma factors.