Chapter 16.5.1 (Exam 4) Post-Transcriptional Regulation

Question 1

What are three ways eukaryotic gene expression can be regulated after transcription?

Answer 1

Alternative splicing – multiple protein forms

Small RNAs– causes RNA silencing

Regulate the amount of protein

Question 2

What is alternative splicing?

Answer 2

Some exons can also be spliced out, resulting in different mature mRNAs from the same gene; results in a family of proteins from a single gene

Question 3

What are isoforms?

Answer 3

Family of different proteins from a single gene; form differently as a result of alternative splicing

Question 4

There are 4 introns in a eukaryotic protein coding gene. Assume that the first and the last exon must remain in the mature mRNA, how many different proteins could be made by alternate splicing of the pre-mRNA from this gene?

Answer 4

12345
1235
1245
1345
125
135
145
15

Question 5

What is the role of small RNAs?

Answer 5

Small RNAs (~22 bp) regulate gene expression, transcribed from noncoding regions of DNAs

Question 6

What are two types of small RNAs?

Answer 6

MicroRNAs (miRNAs)

Small interfering RNAs (siRNAs)

Question 7

How do MicroRNAs (miRNAs) regulate gene expression?

Answer 7

miRNAs inhibit translation by binding to target mRNAs

Each one has, many targets—not very specific

Question 8

How do small interfering RNAs (siRNAs) regulate gene expression?

Answer 8

Bind to target mRNA and cause its degradation

siRNAs are targeted to their sequence of origin – specific