Question 1

The human gene encoding for calcitonin contains six exons and five introns and is located on chromosome 11.The pre-mRNA transcript from this gene can generate either calcitonin or calcitonin gene related peptide (CGRP)in a tissue-specific manner.Calcitonin produced from the thyroid gland is 32 amino acids long and functions to regulate the calcium while CGRP, which contains 37 amino acids, is produced by the brain cells and involved in transmission of pain.Which of the following processes makes production of two functionally and structurally different proteins from the same gene possible?
A)Self-spicing introns
B)Differential transcription
C)Alternative replication
D)5' capping and polyadenylation
E)Alternative RNA processing

Accepted Answer

Alternative RNA processing allows for the generation of multiple mRNA transcripts and, ultimately, multiple protein products from a single gene. This can occur through alternative splicing or differential use of polyadenylation signals, leading to different combinations of exons being included in the final mRNA transcript. In this case, it allows for the production of both calcitonin and CGRP.

Question 2

The spliceosome is a large, ribonucleoprotein complex located in the:
A)cytoplasm.
B)endoplasmic reticulum.
C)Golgi.
D)nucleus.
E)nucleolus.

Accepted Answer

The spliceosome is involved in RNA splicing, which takes place in the nucleus of eukaryotic cells. Therefore, the correct choice is D- nucleus.

Question 3

When does sigma factor normally dissociate from RNA polymerase?
A)After transcription has terminated
B)After the process of initiation
C)After the addition of nucleosomes
D)After the binding of rho
E)Following the addition of nucleosomes

Accepted Answer

Sigma factor normally dissociates from RNA polymerase after the process of initiation.

Question 4

Prokaryotic promoters contain the sequence TATAAT at a position _____ from the transcription start.
A)+1
B)-1
C)-10
D)-25
E)-35

Accepted Answer

The answer of Prokaryotic promoters contain the sequence TATAAT at...

Question 5

Which of the following statements about bacterial mRNA transcript is TRUE?
A)Unlike eukaryotes, bacterial mRNA transcripts do not typically contain untranslated regions.
B)The Shine-Dalgarno box associates with an RNA component in the ribosomes.
C)Transcription and translation take place sequentially in bacterial cells.
D)Most bacterial genes contain a large number of introns and small number of exons.
E)The 5' end and 3' end of mRNA transcripts are modified in bacteria.

Accepted Answer

The Shine-Dalgarno box is a conserved sequence found in the 5' untranslated region of bacterial mRNA transcripts. It base-pairs with a complementary sequence in the RNA component of the ribosome to position the ribosome at the start codon. Therefore, option B is the true statement about bacterial mRNA transcripts. Option A is incorrect because bacterial mRNA transcripts do contain untranslated regions. Option C is incorrect because transcription and translation can occur simultaneously in bacteria due to their lack of a membrane-bound nucleus. Option D is incorrect because bacteria do not have introns in their genes. Option E is incorrect because bacterial mRNA transcripts do not undergo the same types of modification seen in eukaryotic mRNA, such as 5' capping and 3' polyadenylation.

Question 6

If the sequence of an RNA molecule is 5'GGCAUCGACG 3', what is the sequence of the nontemplate strand of DNA?
A)5' GGCATCGACG 3'
B)3' GGCATCGACG 5'
C)5' CCGTAGCTGC 3'
D)3'CCGTAGCTGC 5'
E)3' CGTCGATGCC 5'

Accepted Answer

The nontemplate strand of DNA has the same sequence as the RNA molecule, except that thymine (T) replaces uracil (U). The RNA sequence is 5' GGCAUCGACG 3', so the DNA nontemplate strand is 5' GGCATCGACG 3', matching option A.

Question 7

Scientists once believed that each gene can encode a single polypeptide.We now know that _____ and _____ allow a single gene to encode more than one polypeptide.
A)transcription; translation
B)polyadenylation; RNA transport
C)DNA methylation; chromatin condensation
D)alternative processing; RNA editing
E)gene silencing; RNA interference

Accepted Answer

Alternative processing and RNA editing allow a single gene to produce multiple polypeptides. Alternative processing is the differential splicing of introns and exons during mRNA processing, resulting in different mRNA transcripts and thus different polypeptides. RNA editing involves changes to the nucleotide sequence of mRNA after transcription, resulting in different polypeptides from the same gene.

Question 8

Which of the following is NOT necessary for RNA polymerase to recognize the promoter of a bacterial gene?
A)Sigma factor
B)Origin of replication
C)-10 consensus sequence
D)-35 consensus sequence

Accepted Answer

Origin of replication is not necessary for RNA polymerase to recognize the promoter of a bacterial gene. Sigma factor, -10 consensus sequence and -35 consensus sequence are key elements required for promoter recognition.

Question 9

In prokaryotic RNA polymerases, the holoenzyme consists of the core enzyme and the:
A)rho factor.
B)TFIID.
C)TBP.
D)omega subunit.
E)sigma factor.

Accepted Answer

In prokaryotic RNA polymerases, the holoenzyme consists of the core enzyme and the sigma factor. The sigma factor helps the RNA polymerase to recognize the promoter region and initiate the transcription of a gene.

Question 10

If the following DNA strand were used as a template, what would the sequence of an RNA be? 5' GTACCGTC 3'
A)5'GUACCGUC 3'
B)5'GACGGTAC 3'
C)5' CAUGGCAG 3'
D)5' GACGGUAC 3'
E)5' GUCGGUAC 3'

Accepted Answer

During transcription, the RNA strand is synthesized by complementary base pairing with the DNA template strand. The base pairing rules are A-U and C-G, but in RNA, T is replaced with U. Therefore, the RNA sequence would be 5' GACGGUAC 3'.

Question 11

Which of the following is found on the primary product of transcription but not on a mature mRNA molecule?
A)Start codon
B)Promoter
C)Exons
D)Introns
E)Stop codon

Accepted Answer

Introns are present in the primary transcript (pre-mRNA), and are removed via RNA splicing to create a mature mRNA molecule. The other options are present in both the primary transcript and the mature mRNA molecule.

Question 12

The 5' cap on an mRNA is important for all the processes listed below EXCEPT for the _____ of an mRNA molecule.
A)transcription
B)intron removal
C)stability
D)initiation of translation

Accepted Answer

The 5' cap on an mRNA molecule is not involved in the transcription process. Transcription is the synthesis of RNA from a DNA template, and the 5' cap is added after the initiation of transcription to facilitate other processes such as intron removal, stability, and initiation of translation.

Question 13

Which of the following elements would not be found on an mRNA molecule?
A)Protein-coding region
B)3'untranslated region
C)5' untranslated region
D)Promoter
E)Start and stop codons

Accepted Answer

A promoter is a specific region of DNA that signals the start of a gene and is not found on an mRNA molecule. The other options are all found on mRNA molecules. The protein-coding region contains the instructions for making a protein, the untranslated regions help regulate translation, and the start and stop codons signal the beginning and end of the protein-coding region.

Question 14

How many introns are present on a gene that consists of four exons?
A)two
B)three
C)four
D)five
E)The number cannot be determined from the information provided.

Accepted Answer

Introns are non-coding regions of a gene that are removed during RNA splicing, leaving only exons, the coding regions, to be expressed. A gene with four exons will have three introns, as introns are located between exons.

Question 15

In 1958, Francis Crick proposed that genes and their corresponding polypeptides are "colinear." Which of the following statements concerning the concept of colinearity is INCORRECT?
A)Colinearity means that the linear nucleotide sequence of a given gene corresponds directly to the linear amino acid sequence in the corresponding polypeptide.
B)The number of nucleotides in a gene should be precisely proportional to the number of amino acids present in the corresponding polypeptide.
C)Colinearity generally holds true for the coding regions of prokaryotic viral genes.
D)The vast majority of eukaryotic genes also follow the concept of colinearity although the size of genes may be larger.

Accepted Answer

The concept of colinearity does not generally hold for the vast majority of eukaryotic genes due to the presence of introns and exons; the coding sequences (exons) are interrupted by non-coding sequences (introns), which means the linear nucleotide sequence of the gene does not directly correspond to the amino acid sequence of the protein.

Question 16

An in vitro transcription system that contains a bacterial gene initiates transcription but from random points on the DNA.Which of the following proteins MOST likely is missing from the reaction?
A)Sigma factor
B)Rho factor
C)RNA polymerase II
D)TATA-binding protein (TBP)
E)TFIID

Accepted Answer

Sigma factors are subunits of bacterial RNA polymerase that bind to specific DNA sequences, known as promoters, and facilitate the initiation of transcription from a defined start site. Without sigma factor, RNA polymerase cannot properly initiate transcription at the correct location on the DNA, leading to transcription starting from random points. Rho factor is involved in transcription termination in bacteria, while RNA polymerase II, TBP and TFIID are components of the eukaryotic transcription machinery and do not play a role in prokaryotic transcription.

Question 17

Which mechanism allows for more than one polypeptide to be encoded by a single gene?
A)Regulated transcription
B)RNA interference
C)Alternative RNA processing
D)Self-splicing of introns
E)RNA methylation

Accepted Answer

Alternative RNA processing allows for more than one polypeptide to be encoded by a single gene by utilizing different combinations of exons during splicing to produce different mRNA transcripts, which can then be translated into different protein isoforms. This is commonly seen in genes that have multiple exons that can be alternatively spliced, resulting in different functional domains or regulatory regions in the protein.

Question 18

Which of the following classes of RNAs is unique to the eukaryotes?
A)Messenger RNA (mRNA)
B)Ribosomal RNA (rRNA)
C)Transfer RNA (tRNA)
D)Small nuclear RNAs (snRNAs)
E)CRISPR RNAs (crRNAs)

Accepted Answer

Small nuclear RNAs (snRNAs) are unique to eukaryotes and play a crucial role in RNA splicing, a process that involves the removal of introns from pre-mRNA. mRNA, rRNA, tRNA, and crRNAs are found in both eukaryotes and prokaryotes.

Question 19

Anticodons are found on _____ molecules.
A)mRNA
B)tRNA
C)rRNA
D)snRNA
E)miRNA

Accepted Answer

Anticodons are part of tRNA molecules, not mRNA, rRNA, snRNA, or miRNA.

Question 20

An in vitro transcription system that contains a bacterial gene does not initiate transcription.What is one possible problem?
A)Histones that were on the DNA when it was isolated from E.coli are blocking access to the template.
B)There is a mutation in the inverted repeat sequence that prevents a hairpin secondary structure from forming.
C)There is a mutation at -10, where a promoter consensus sequence is located.
D)Rho factor has not been added.
E)TATA-binding protein (TBP)has not been added.

Accepted Answer

A mutation at the -10 region of the promoter consensus sequence would prevent RNA polymerase from binding and initiating transcription.

Quiz 10: From DNA to Proteins- Transcription and Rna Processing

The spliceosome is a large, ribonucleoprotein complex located in the:

When does sigma factor normally dissociate from RNA polymerase?

Prokaryotic promoters contain the sequence TATAAT at a position _____ from the transcription start.

Which of the following statements about bacterial mRNA transcript is TRUE?

If the sequence of an RNA molecule is 5'GGCAUCGACG 3', what is the sequence of the nontemplate strand of DNA?

Scientists once believed that each gene can encode a single polypeptide.We now know that _ and _ allow a single gene to encode more than one polypeptide.

Which of the following is NOT necessary for RNA polymerase to recognize the promoter of a bacterial gene?

In prokaryotic RNA polymerases, the holoenzyme consists of the core enzyme and the:

If the following DNA strand were used as a template, what would the sequence of an RNA be? 5' GTACCGTC 3'

Which of the following is found on the primary product of transcription but not on a mature mRNA molecule?

The 5' cap on an mRNA is important for all the processes listed below EXCEPT for the _____ of an mRNA molecule.

Which of the following elements would not be found on an mRNA molecule?

How many introns are present on a gene that consists of four exons?

In 1958, Francis Crick proposed that genes and their corresponding polypeptides are "colinear." Which of the following statements concerning the concept of colinearity is INCORRECT?

An in vitro transcription system that contains a bacterial gene initiates transcription but from random points on the DNA.Which of the following proteins MOST likely is missing from the reaction?

Which mechanism allows for more than one polypeptide to be encoded by a single gene?

Which of the following classes of RNAs is unique to the eukaryotes?

Anticodons are found on _____ molecules.

An in vitro transcription system that contains a bacterial gene does not initiate transcription.What is one possible problem?