Question 1

Small regulatory RNA can regulate gene expression by:

Accepted Answer

The answer of Small regulatory RNA can regulate gene expression...

Question 2

Unlike processing of the primary transcript, RNA editing occurs at the level of mRNA.

Accepted Answer

RNA editing is a post-transcriptional modification that can occur at the level of mature mRNA. It involves changes in the nucleotide sequence of mRNA molecules through the addition, deletion, or modification of specific bases, which can affect the coding potential and stability of the transcript. In contrast, processing of the primary transcript involves a series of steps that convert the initial RNA molecule into a functional mRNA molecule, including capping, splicing, and polyadenylation, and occurs in the nucleus before the mRNA is exported to the cytoplasm for translation.

Question 3

Small regulatory RNAs can modify gene expression by inhibiting:

Accepted Answer

The answer of Small regulatory RNAs can modify gene expression...

Question 4

Certain genes have apparently unusual inheritance patterns. For instance, in the mouse autosomal gene H19, only the copy inherited from the mouse's mother is expressed. Conversely, in the mouse autosomal gene Igf2, only the copy inherited from the mouse's father is expressed. The consequence of this is that imprinted genes are expressed as if they were present in only one copy, even though there are two copies of each of these genes in each cell. What process or processes are responsible for this phenomenon?

Accepted Answer

Imprinted genes are controlled by epigenetic modifications, such as DNA methylation and histone modification, that are established during gametogenesis and maintained through cell division in a parent-of-origin-specific manner. These modifications result in the differential expression of imprinted genes depending on whether they are inherited from the mother or the father. This phenomenon is called genomic imprinting.

Question 5

The 5'UTR and 3' UTR of mRNA may bind with proteins that:

Accepted Answer

The answer of The 5'UTR and 3' UTR of mRNA...

Question 6

Which of the following does NOT occur during RNA processing?

Accepted Answer

RNA splicing involves the removal of introns and the joining of exons to generate a mature mRNA molecule. It does not involve the removal of all exons. The other options (A, B, D, and E) are all processes that occur during RNA processing.

Question 7

Suppose that the RNA sequence shown here is a target for a microRNA. 5'-AAUGCUACG-3'
Which of these double-stranded precursor RNA molecules could be processed for incorporation into RISC to target the sequence?

Accepted Answer

The answer of Suppose that the RNA sequence shown here...

Question 8

Lysosomes are organelles that normally contain enzymes that break down proteins in order to recycle proteins in the cell. A family of genetic disorders, called lysosomal storage disorders, has defects in this system. In some of these diseases, proteins that normally move to the lysosomes fail to be transported properly in the cell. As a result, lysosomes do not properly recycle proteins. Which of the following could produce this kind of disorder?

Accepted Answer

Lysosomal storage disorders often result from the improper transport of proteins to lysosomes, which can be caused by issues in post-translational modification. This process is crucial for the proper sorting and functioning of proteins, including those needed for the lysosome's recycling capabilities.

Question 9

Primary RNA transcripts can be spliced differently so that the same primary transcript generated from a single gene can give rise to more than one kind of processed mRNA transcript and thus more than one kind of protein.

Accepted Answer

Primary RNA transcripts can undergo alternative splicing, where different combinations of exons are included or excluded, producing different mRNA transcripts and therefore different proteins, even from the same gene.

Question 10

A mutation is found that prevents transcription of the HOX3A gene, which is known to be in chromosome 12. Genetic mapping of the mutation suggests that it is located in chromosome 11. Which of the following could make these two observations possible?

Accepted Answer

This mutation affects transcription of the HOX3A gene, suggesting that it disrupts a transcription factor necessary for the transcription of the gene. The fact that the genetic mapping suggests the mutation is located in chromosome 11 is likely due to a nearby transcription factor gene that is necessary for the transcription of HOX3A.

Question 11

Which of the following changes could cause the production of a shorter-than-normal protein from a gene?

Accepted Answer

The answer of Which of the following changes could cause...

Question 12

Modification of bases in mRNA transcripts can change the mRNA sequence and thus the characteristics of the protein for which it codes.

Accepted Answer

Modifications of bases in mRNA transcripts, such as splicing and editing, can result in changes to the resulting protein sequence and thus alter its characteristics.

Question 13

Modification of histone tails is one mechanism of:

Accepted Answer

Modification of histone tails involves the addition or removal of specific chemical groups, such as acetyl or methyl groups, which can affect the chromatin structure and influence gene expression. This process is a post-translational modification because it occurs after the histones have been translated from DNA. RNA editing and processing refer specifically to modifications of RNA molecules, whereas X-inactivation is a process in which one of the X chromosomes in female cells is silenced to ensure equal expression of X-linked genes between males and females.

Question 14

Suppose that the RNA sequence shown here is a target for a microRNA. 5'-UUACGAUGC-3'
Which of these double-stranded precursor RNA molecules could be processed for incorporation into RISC to target the sequence?

Accepted Answer

The answer of Suppose that the RNA sequence shown here...

Question 15

The enzymatic processing of a polypeptide chain is an example of:

Accepted Answer

Enzymatic processing of a polypeptide chain occurs after transcription and translation, making it a post-transcriptional modification. The other options are not related to this process.

Question 16

Small regulatory RNAs work in conjunction with:

Accepted Answer

Small regulatory RNAs work in conjunction with RISC proteins to silence gene expression by binding and degrading complementary messenger RNAs. RNA polymerase is responsible for transcribing DNA to RNA, nucleosomes are involved in organizing and packaging DNA, and ribosomal RNA is involved in protein synthesis.

Question 17

Which one of the following is NOT a result of RNA editing?

Accepted Answer

The recruitment of RNA polymerase following the binding of general transcription factors is not a result of RNA editing. RNA editing involves modifications to the nucleotide sequence of an RNA molecule, while the recruitment of RNA polymerase is part of the process of transcription initiation.

Question 18

In eukaryotes, initiation of translation of a messenger RNA is determined in part by:

Accepted Answer

The 5' cap is a modified guanine nucleotide that is added to the 5' end of eukaryotic mRNAs. The cap is required for efficient translation initiation, as it helps to recruit the ribosome to the mRNA.

Question 19

Primary RNA transcripts are always spliced in the same fashion in order to maintain continuity.

Accepted Answer

Primary RNA transcripts undergo alternative splicing, which allows for different variations of the final mRNA molecule to be produced. This can result in the inclusion or exclusion of certain exons, leading to different protein products.

Question 20

Among the exons in a primary RNA transcript, two are subject to alternative splicing. In RNA processing, one or the other or neither or both regions may be excised from the primary transcript as introns. How many different amino acid sequences could this transcript encode?

Accepted Answer

Given two exons subject to alternative splicing, each exon can either be included or excluded, leading to four possible combinations: both included, both excluded, only the first included, or only the second included. Each combination could potentially encode a different amino acid sequence.

Quiz 19: Genetic and Epigenetic Regulation