GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with RNA in Gene Regulation

Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology

varsity tutors app store varsity tutors android store

All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

1 Diagnostic Test 201 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #1 : Help With Rna In Gene Regulation

Which of the following types of RNA have been shown to regulate protein synthesis?

I. lncRNA

II. miRNA

III. tRNA

Possible Answers:

I and II

I and III

II only

I, II, and III

Correct answer:

I, II, and III

Explanation:

Protein synthesis can be directly affected by molecules involved in translation, or indirectly by molecules involved in the transcription of mRNA templates.

Transfer RNA (tRNA) is involved in translation and serves the function of bringing amino acids to ribosomes. Due to its important function in translation tRNA, is capable of globally controlling translation and, therefore, is involved in protein regulation.

Long non-coding RNA (lncRNA) has been shown to regulate transcription in a number of ways. One of the most prominent is the existence of a lncRNA (Xist) that inactivates the majority of the extra X-chromosome in human females.

Micro RNA (miRNA) is involved in a process known as RNAi and is capable of controlling the translation of targeted molecules of mRNA. 

Example Question #2 : Help With Rna In Gene Regulation

X-chromosome inactivation occurs in females in which one X-chromosome is silenced and transcriptionally inactivated. The X-inactive specific transcript (Xist) gene is responsible for mediating this inactivation. 

What does Xist encode?

Possible Answers:

Long non-coding RNA

Protein

Ribosomal RNA 

Piwi-interacting RNA 

MicroRNA

Correct answer:

Long non-coding RNA

Explanation:

The correct answer is long non-coding (lnc) RNA. Xist lncRNA coats the X-chromosome from which it is transcribed, effectively silencing that X-chromosome. MicroRNAs are small RNAs (~20 base pairs (bp)) and play a role in RNA silencing and post-transcriptional regulation of gene expression. Short interfering RNAs are double-stranded (20-25 bp) and play a role in post-transcriptional gene silencing. Piwi-interacting RNAs are small non-coding RNAs that interact with piwi proteins in epigenetic and post-transcriptional silencing of genetic elements such as retroposons. While MicroRNAs, siRNAs and Piwi-interacting RNAs all silence genes, the mechanism of X-chromosome inactivation requires Xist lncRNA. 

All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

1 Diagnostic Test 201 Practice Tests Question of the Day Flashcards Learn by Concept
Learning Tools by Varsity Tutors

Incompatible Browser

Please upgrade or download one of the following browsers to use Instant Tutoring: