Control of gene expression in eukaryotes part 4

Question 1

Define RNAi

Answer 1

A mechanism by which very selective degradation of mRNA takes place

Question 2

Define the role of Dicer

Answer 2

cuts dsRNA into 22 nt pieces

Question 3

Define siRNA

Answer 3

22bp of target mRNA

Question 4

Define RISC

Answer 4

RNA-induced silencing complex

A complex of proteins that takes the siRNA and matches it to the target RNA, and then cleaves the RNA

Question 5

Define Argonaut

Answer 5

Protein in RISC that cleaves the dsRNA

Question 6

Define microRNAs

Answer 6

• A way of attacking mRNA from an intrinsic source

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Question 7

What are the two ways microRNA can work?

Answer 7

1. perfect match: degradation of mRNA immediately

2. Imperfect match: transportation to p bodies for degradation

Question 8

Define RITS?

Answer 8

RNA-induced transcriptional silencing complex.

Question 9

How does RITS work?

Answer 9

RITS interacts with mRNA exiting RNA pol. The presence of RITS near the gene attracts CRCs, to create heterochromatin

Question 10

There will probably be a question of comparing the different types of RNA.

Answer 10

Ok

Question 11

What are four modes of negative control in eukaryotes

Answer 11

1. Protein inhibits stat or stop codon
2. Cold temperatures cause hairpin, hiding start codon
3. Small molecule creates hairpin that hides start codon
4. antisense RNA covers the start codon

Question 12

Define ferritin

Answer 12

Protein that binds iron when it is in excess

Question 13

Define transferrin receptor

Answer 13

Protein that transports iron through the plasma membrane

Question 14

What is eIF-2?

Answer 14

A factor needed for assembly of the 40S unit of the ribosome

Question 15

What is the role of eIF2B?

Answer 15

It is responsible for exchanging GDP for GTP on EiF-2