Chapter 14 Flashcards by Davesh Purohit

Which of the following statements correctly describes the facts about introns and exons?

a. The number of introns is always less than the number of exons in a gene.
b. Introns are degraded in the cytoplasm.
c. All eukaryotic genes contain an intron.
d. Mitochondrial and chloroplast genes do not contain introns.
e. Introns do not contain sequence-specific information.

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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 coliniarity although the size of genes may be larger.
e. The exception to colinearity between genes and polypeptides is the presence of untranslated sequences (UTRs).

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How many introns are present on a gene that consists of 4 exons?

a. 2
b. 3
c. 4
d. 5
e. The number cannot be determined from the information provided.

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Which of the following statements regarding gene structure is NOT false?

a. The amino acid sequence of a polypeptide can be precisely predicted by the nucleotide sequence of the gene that encodes it.
b. The number of introns found in organisms is species specific.
c. The number of exons and introns generally correlate to the complexity of the organisms.
d. Intron cleavage and exon splicing are both mediated by protein enzymes.
e. The number of exons is always less than the number of introns in a gene.

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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 small subunit of ribosomes.
c. Transcription and translation take place sequentially in bacterial cells.
d. Most of 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.

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Which of the following statements about ribosomes and ribosomal RNA is NOT true?

a. Ribosomes typically contain about 80% of the total cellular RNA.
b. Ribosomal RNA is processed in both prokaryotes and eukaryotes.
c. In eukaryotes, genes for rRNA are usually present within tandem repeats.
d. Each ribosomal RNA component is encoded by separate gene.
e. In eukaryotes, the rRNA transcripts are processed further by snoRNAs within the nucleus.

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The spliceosome is a large, ribonucleoprotein complex located in the

a. cytoplasm.
b. endoplasmic reticulum.
c. Golgi.
d. nucleus.
e. nucleolus.

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The 5′ and 3′ untranslated regions (UTRs) of processed mRNA molecules are derived from

a. exons.
b. introns.
c. promoter.
d. terminator.
e. protein-coding region.

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Which of the following statements about group I and group II introns is NOT true?

a. Both group I and II introns form elaborate and characteristic secondary structures with loops.
b. The splicing mechanism of group II introns is similar to that of spliceosome mediated nuclear pre-mRNA splicing.
c. The length of group I and group II introns is much longer than the exons within the structures.
d. Group I and group II introns are exclusively found in mitochondrial and chloroplast encoded genes.
e. Both Group I and group II introns are both found in bacterial genes.

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Which of the following best explains why only pre-mRNA is recognized and receives a 5′ cap?

a. The enzyme that initiates the capping step is known to associate with RNA polymerase II, which generate mRNAs.
b. Only pre-mRNAs contain proper sequence for the cap to be added on.
c. The tail of the pre-mRNA can recruit the right combination of enzymes for capping.
d. Nuclear pore complex only recognize pre-mRNA to be allowed out to the cytoplasm for capping process to begin.
e. rRNA and tRNAs do not exit the nucleus to receive the cap via enzyme sin the cytoplasm.

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Which of the following phenomena is not affected by the presence of alternative splicing?

a. Speciation
b. Development
c. Organismal complexity
d. Tissue specificity
e. RNA interference

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Which of the following spliceosomal components specifically recognizes and binds to the branch point of the intron during pre-mRNA splicing?

a. U1
b. U2
c. U5
d. U6
e. Spliceosomal proteins

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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 trnascription
c. Alternative replication
d. 5′ capping and polyadenylation
e. Alternative RNA processing

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Guide RNAs are needed in

a. transcription.
b. translation.
c. RNA interference.
d. RNA editing.
e. RNA splicing.

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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

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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

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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

The information needed during RNA editing comes most directly from

a. pre-mRNA.
b. mRNA.
c. rRNA.
d. tRNA.
e. guide RNA.

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
gene silencing; RNA interference

Which mechanism allows for the production of polypeptides that are not entirely encoded by DNA?

a. Regulated transcription
b. RNA interference
c. Alternative RNA processing
d. RNA editing
e. None of the above

The list of events below describes intron removal and splicing during pre-mRNA processing. Please select the choice that lists the events in correct sequential order.

Attachment of snRNP U1 to the 5′ splice site
Transcription of the DNA template into the pre-mRNA molecule
Release of lariat structure
Splicing together of exons
Transesterification reaction at the branch point adenine

a. 1, 2, 3, 4, 5
b. 4, 1, 3, 5, 2
c. 2, 1, 5, 3, 4
d. 3, 5, 1, 2, 4
e. 5, 3, 4, 1, 2

The list of events below describes eukaryotic pre-mRNA processing. Please select the choice that lists the events in correct sequential order.

Recognition and binding the 3′ AAUAAA sequence by specific protein factors
Cleavage at the poly(A) site
Addition of the 5′ cap
Export to the cytoplasm
Addition of the poly(A) tail

a. 3, 1, 2, 5, 4
b. 2, 3, 4, 5, 1
c. 4, 2, 3, 1, 5
d. 1, 3, 5, 4, 1
e. 5, 4, 1, 3, 2

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
e. ribosomal interaction

A key modification in the 3′ end of eukaryotic mRNA is the addition of 50 to 250 adenine nucleotides at the 3′ end, forming a poly(A) tail. Which of the following statements is not a salient feature of this polyadenylation reaction?

a. The stability of mRNA transcripts in the cytoplasm is affected by poly(A) tail.
b. Poly(A) tail facilitates the attachment of the ribosomes to the mRNA.
c. Proper poly(A) tail is important for proper nuclear export of mRNA.
d. Poly(A) tail at the 3′ end translates to a long stretch of repeated amino acids.
e. Multiple proteins will recognize and bind to poly(A) tail in the cytoplasm.

During the post transcriptional processing of pre-mRNA, a 5′ cap is added to an mRNA. Arrange the following events in correct order for the capping process. 1. Addition of guanine nucleotide via 5′-5′ bond 2. Removal of a phosphate from a ribonucleotide triphosphate at the 5′ head of pre-mRNA 3. Methylation to the 2′ position of the sugar in the second and the third nucleotide 4. Methylation at the 5′ end and addition of methyl group to the position 7 of the terminal guanine base a. 1, 2, 3, 4 b. 2, 4, 1, 3 c. 4, 1, 3, 2 d. 2, 1, 4, 3 e. 3, 2, 4, 1

During the post transcriptional processing of pre-mRNA, a 5′ cap is added to an mRNA in step by step manner. Which of the following reason prevents the possibility of 5′ capping process involving methylation occurring on a DNA strand? a. Lack of OH group on 2′ carbon of the deoxyribose b. Lack of OH group on 3′ carbon of the deoxyribose c. Lack of uracil nitrogenous base on the DNA strand d. Lack of GTP hydrolysis associated with DNA transcription e. Lack of H on 4′ carbon of the deoxyribose

Which of the following consensus sequences are NOT found in nuclear introns? a. GU at the 5′ splice site at the beginning of the intron b. AG at the 3′ splice site at the end of the intron c. CCA at the 3′ site downstream of the branch point d. A at the lariat branch point site e. 3′ CAGG consensus sequence at the 3′ splice junction

What do group I and group II introns have in common? a. Both are found in mitochondrial genes. b. Both are found in bacteriophages. c. Both are known to be self-splicing introns. d. Both are found in protein-coding genes of chloroplasts. e. Both are frequently found in eukaryotic genes.

Which of the following correctly describes the concept of alternative splicing? a. Eukaryotic gene and protein sequences are precisely colinear. b. With the rare exception of RNA editing, every nucleotide contained in a processed mRNA molecule is derived from exon sequences. c. Every other intron is removed in alternate manner to generate functional mRNA transcript. d. Only a subset the same mRNA transcripts are specifically selected for splicing in the nucleus. e. Multiple protein products are often produced from single eukaryotic genes.

Which of the following nitrogenous bases is frequently modified enzymatically to become rare type of nitrogenous base upon transcription of tRNA gene? a. Adenine b. Uracil c. Thymine d. Cytosine e. Guanine

Anticodons are found on _______ molecules. a. mRNA b. tRNA c. rRNA d. snRNA e. miRNA

Which of the following choices does not support the notion that the gene is much more than DNA sequences that are transcribed into a single RNA molecule that encodes a single polypeptide? a. Alternative splicing—a single gene can yield multiple mRNA and protein products. b. A single ribosomal RNA transcripts can liberate several RNA molecules via further processing c. RNAs can be the functional product of a gene without being translated into protein product d. Protein coding region—each codon represents specific amino acid that will be linked to form a polypeptide e. Regulatory elements are part of a gene that regulate timing, degree, and specificity of gene expression but are not transcribed.

To which part on tRNAs would an amino acid attach to during tRNA charging? a. 3′ acceptor arm b. Anticodon arm c. TψC arm d. DHU arm e. Extra arm

Which of the following rRNA components originates from a separate gene transcript rather than as a cleaved product of a long single precursor rRNA transcript? a. Prokaryotic 16S rRNA b. Prokaryotic 23S rRNA c. Eukaryotic 18S rRNA d. Eukaryotic 5.8S rRNA e. Eukaryotic 5S rRNA

The list of events below describes the processing of ribosomal RNAs. Please select the choice that lists the events in correct sequential order. 1. Methyl groups are added to specific bases and the 2′-carbon atom of some ribose sugars 2. Transcription of the rRNA precursors from DNA 3. Cleavage of precursor rRNA 4. Individual rRNA molecules ready for ribosome assembly 5. Trimming of precursor rRNA a. 3, 1, 2, 5, 4 b. 2, 3, 4, 5, 1 c. 4, 2, 3, 1, 5 d. 1, 3, 5, 4, 1 e. 2, 1, 3, 5, 4

Which class of RNA is most abundant in cells? a. mRNA b. tRNA c. rRNA d. snRNA e. miRNA

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)

siRNAs and miRNAs function in which of the following processes? a. Transcription b. Translation c. RNA interference d. RNA editing e. RNA splicing

What is the similarity among miRNAs, siRNAs, and piRNAs? a. All three types originate from transposons or viruses and are found in all organisms. b. They target and degrade the gene from which they were transcribed. c. All three are generated from a single-stranded RNA that gets cleaved. d. All of them can influence chromatin structure, which in turn, can influence gene expression. e. All three associate with Piwi proteins to be able to function in RNA degradation.

Which of the following small RNA types is unique to prokaryotes? a. siRNA b. crRNA c. miRNA d. piRNA e. lncRNA

Which of the following regulatory RNA types is different from the rest in terms of its length? a. siRNA b. crRNA c. miRNA d. piRNA e. lncRNA