Question 1

A knockout mutation in the X-inactive specific transcript (XIST)lncRNA of mice would result in

Accepted Answer

XIST is crucial for X chromosome inactivation in female mammals. A knockout mutation would prevent X inactivation, leading to two active X chromosomes in female mice.

Question 2

The most significant influence on why mRNA is processed differently in prokaryotes than eukaryotes is the fact that

Accepted Answer

The main reason why mRNA is processed differently in prokaryotes than eukaryotes is that eukaryotes have a nucleus, which separates transcription and translation. This allows for additional processing and modifications of the mRNA before it is transported to the cytoplasm for translation. In contrast, prokaryotes do not have a nucleus and transcription and translation occur simultaneously in the cytoplasm. Therefore, mRNA processing in prokaryotes is limited compared to eukaryotes.

Answer: B
 Another factor that influences why mRNA is processed differently in prokaryotes than eukaryotes is the fact that prokaryotes are often polycistronic, meaning that multiple genes can be transcribed on a single mRNA molecule. In contrast, eukaryotes are typically monocistronic, meaning that each mRNA molecule codes for a single gene. This requires additional processing steps in eukaryotes to ensure proper splicing and termination of the mRNA transcript.

Question 3

Which class of RNA molecules is unique to eukaryotic organisms?

Accepted Answer

Small nuclear RNA (snRNA) is unique to eukaryotic organisms and is involved in the processing of pre-mRNA transcripts. Transfer RNA (tRNA), ribosomal RNA (rRNA), and messenger RNA (mRNA) are present in both prokaryotic and eukaryotic organisms.

Question 4

The RNA type directly involved in protein synthesis is

Accepted Answer

Ribosomal RNA (rRNA) is directly involved in protein synthesis as it is a component of ribosomes, the site of protein synthesis. Small nuclear RNA (snRNA) is involved in splicing in the processing of pre-mRNA, short interfering RNA (siRNA) is involved in gene silencing, and long non-coding RNA (ncRNA) has various roles in gene regulation but not directly involved in protein synthesis.

Question 5

RNA is a dynamic biomolecule because it can

Accepted Answer

RNA is a dynamic biomolecule because it plays multiple roles in cells. It can act as a template for protein synthesis, regulate gene expression and protein synthesis, and be synthesized and function in the cell nucleus. While RNA can also catalyze certain reactions, this is not the main reason it is considered dynamic. Its stability to hydrolysis varies and is not necessarily a defining characteristic. The presence of a ribose sugar backbone is a common feature of RNA, but it alone does not make it dynamic.

Question 6

RNA is a highly dynamic biomolecule in that it

Accepted Answer

Unlike DNA, RNA is single-stranded, which allows it to fold and establish H-bonds with itself or other molecules to form complex tertiary structures that regulate gene expression and participate in many cellular processes. Moreover, RNA can recognize and interact with proteins, small molecules, and nucleic acids through specific binding sites that depend on its unique three-dimensional structure. So, option A is correct.

Answer: B, C, and D are incorrect.
 Option B is incorrect because RNA can form stable H-bonds with complementary nucleotides and protein side chains, although it may be more prone to structural fluctuations than DNA. Option C is also incorrect because RNA can be as long as some DNA molecules or even longer. Moreover, several functional RNA molecules are as short as a few nucleotides or even base pairs. Finally, option D is incorrect because although RNA has a backbone made of alternating sugar and phosphate units, it also contains nitrogenous bases that play key roles in its structure and function.

Question 7

Of the following protein synthesizing RNA molecules,which codes for a protein?

Accepted Answer

Only mRNA (messenger RNA) codes for a protein. tRNA (transfer RNA) carries amino acids to the ribosome during protein synthesis, rRNA (ribosomal RNA) forms the structure of ribosomes, and siRNA (small interfering RNA) is involved in RNA interference and gene regulation, but they do not directly code for proteins.

Question 8

Which of the following is a coding RNA molecule?

Accepted Answer

The answer of Which of the following is a coding...

Question 9

Which is often removed from eukaryotic mRNA before translation?

Accepted Answer

Introns are non-coding regions of mRNA that are often removed by splicing before translation. The coding regions, or exons, are typically left intact. Poly(A) tails are added to the 3' end of mRNA and aid in stability and recognition by translation machinery. Polycistrons are found in prokaryotic mRNA and contain multiple coding regions for different genes.

Question 10

RNA is typically more susceptible to backbone hydrolysis than DNA because of the

Accepted Answer

The answer of RNA is typically more susceptible to backbone...

Question 11

It has been estimated that as much as __________ % of the human genome is transcribed into noncoding RNA,whereas __________ % of the E.coli genome is noncoding RNA.

Accepted Answer

The answer of It has been estimated that as much...

Question 12

Which of the following RNA molecules has the LEAST number of different sequences in a given organism?

Accepted Answer

rRNA (ribosomal RNA) is a highly conserved RNA molecule found in all organisms, and there are relatively few differences in its sequence across different species. In contrast, mRNA (messenger RNA) and snRNA (small nuclear RNA) can vary widely between different cells and tissues, and tRNA (transfer RNA) can also vary depending on the specific aminoacyl-tRNA synthetase enzymes present in an organism. Therefore, rRNA has the least number of different sequences in a given organism.

Question 13

Long noncoding RNA (lncRNA)is generated from

Accepted Answer

Long noncoding RNAs are generated from the transcription of genomic DNA, which is then processed by splicing and other post-transcriptional modifications. They do not come from the tips of chromosomes, the splicing of used mRNA, or an infection of viral RNA.

Question 14

Prokaryotic mRNA is commonly processed through

Accepted Answer

Prokaryotic mRNA is not processed through splicing, addition of 7-methylguanylate cap, or removal of exons. Instead, it is immediately translated during transcription.

Question 15

Which enzyme is important in the processing of tRNA and mRNA from prokaryotes?

Accepted Answer

RNaseP is an enzyme responsible for cleaving the precursor tRNA molecule into the mature tRNA molecule. It is also involved in the processing of mRNA in prokaryotes. The other choices - snRNA, reverse transcriptase, and ribozyme - are not specifically involved in the processing of tRNA and mRNA in prokaryotes.

Question 16

Which protein-synthesizing RNA molecule carries an amino acid to the ribosome active site?

Accepted Answer

The answer of Which protein-synthesizing RNA molecule carries an amino...

Question 17

Which RNA molecule does NOT bind to the ribosome?

Accepted Answer

snRNA (small nuclear RNA) is involved in RNA processing in the nucleus and does not bind to ribosomes. tRNA (transfer RNA) brings amino acids to the ribosome during protein synthesis, rRNA (ribosomal RNA) is a component of the ribosome, and mRNA (messenger RNA) carries genetic information from the DNA to the ribosome.

Question 18

Which class of RNA molecule is typically the shortest in length?

Accepted Answer

Micro RNA (miRNA) is typically the shortest in length, usually around 20-24 nucleotides long.

Question 19

A 7-methylguanylate cap and poly(A)tail is added to mRNA to

Accepted Answer

The addition of a 7-methylguanylate cap and poly(A) tail on the mRNA molecule facilitates binding and translation by the ribosome. The cap helps in binding the mRNA to the ribosome, while the length of the poly(A) tail aids in efficient translation.

Question 20

How are RNA structures different from protein structures?

Accepted Answer

The answer of How are RNA structures different from protein...

Quiz 21: Rna Synthesis, processing, and Gene Silencing

A knockout mutation in the X-inactive specific transcript (XIST) lncRNA of mice would result in