RNA Structure, Synthesis and Post-Transcription Process

Question 1

Shine Delgarno sequence

Answer 1

Site where ribosome binds during transcription and translation

Question 2

Eukaryotic Large Subunit

Answer 2

60S (28S, 5.8S and 5S)

Question 3

Eukaryotic Small subunit

Answer 3

40S (18S)

Question 4

Prokaryotic Large subsunit

Answer 4

50S (4S and 23S)

Question 5

Prokaryotic Small subunit

Answer 5

30S (16S)

Question 6

microRNA regulates post-transcriptional or post-translational?

Answer 6

Post-translational?

Question 7

Template strand is also called…

Answer 7

Antisense

Question 8

Coding strand is called…

Answer 8

Sense

Question 9

RNA Polymerase– Prokaryotes

Answer 9

Composed of subunits alpha2, beta beta 1, and sigma

Question 10

RNA Polymerase– Eukaryote

Answer 10

RNA Polymerase I, II, III, mitochondrial

Question 11

Sigma subunit–Prokaryotic RNA polymerase

Answer 11

Recognizes and binds to promoter, DNA strand unwinds -> initiation of transcription

Question 12

Rho=independent termination of transcription in prokaryotes

Answer 12

DNA template has a region of symmetry, followed by series of adenine residues. The RNA transcript will fold back to form a hairpin loop ->

Question 13

Post-Transcriptional Processing

Answer 13

• Base modification
• Sugar modification
• Addition to 5’ and 3’ ends
• Exo- and endo-nucleolytic cleavage
• Excision of internal, non-coding (intron) sequences

Question 14

Role of RNA Splicing

Answer 14

• Removal of intron sequences
• Alternative splicing results in gene variants. Coding capacity of a single gene is increased.
• Generate non-coding RNA molecules - regulators of gene exression (e.g. microRNAs)
• Intron has consensus sequences that tag the exon boundary

Question 15

snurps

Answer 15

Small snurps form anchors which serve to recognize on the 5’ end of the intron and the 3’ end of the intron. Intron sequence is excised. The two exons are then joined together

Question 16

Beta-Thalassemia

Answer 16

Enzyme of a disease with splice site mutations (size of mRNA will be altered

Question 17

Systemic Lupus Erythematosus

Answer 17

An autoimmune disease in which the patient produces antibodies to snRNPs

Question 18

Structure of Eukaryotic Gene

Answer 18

Length of DNA that directs the synthesis of a polypeptide or functional RNA molecule

Question 19

POMC

Answer 19

Example of Eukaryotic Polycistronic Gene

Question 20

Post-transitional processing vs post-transcriptional processing

Answer 20

Post-transcriptional processing has three components: 5’ capping, 3’ polyadenylation, and RNA splicing. All occurs in the cell nucleus. microRNA may be an example, which is
a cellular RNA fragment that prevents the production of a particular protein by binding to and destroying the messenger RNA that would have produced the protein

Post-translational modification: covalent and generally enzymatic modification of proteines during or after protein biosynthesis. Forms the mature protein product.

This occurs after the protein is made. Conversely, alternative slicing occurs with RNA

Question 21

Actinomycin D

Answer 21

Inhibits the transient unwinding of DNA

Question 22

Ethidium bromide

Answer 22

Intercalates between DNA and blocks unwinding

Question 23

Rifampicin

Answer 23

Inhibits beta subunit of prokaryotic RNA polymerase

Question 24

alpha-Amanitin

Answer 24

RNA polymerase II is highly sensitive to this drug. Found in poisonous mushrooms