Post Transcriptional Control of expression of RNAi

Question 1

How does RNA differ from DNA?

Answer 1

rna less stable than dna
dna is information storage
rna single stranded
rna forms variety of 3d shapes
rna variety of functions
rna more transient

Question 2

What happens in eukaryotic pre-mRNA processing?

Answer 2

Splicing
removal of introns
creates mature mRNA

5- cap added
poly A tail on 3’

Question 3

What is an open reading frame?

Answer 3

stretch of codons that start with a start codon and end with a stop codon

transcript then translated into a protein

Question 4

Splicing

Answer 4

exons are not scrambled
different exons included or excluded dependent on gene
creates different protein isoforms

can occur in tissue specific manner

Question 5

how is alternative splicing regulated?

Answer 5

according to tissue type
multiple different splicing variants within a cell

by activators and repressors
- mask binding site or encourage binding

negative control = repressor and no splicing
positive control = activator and splicing

Question 6

What is RNA editing?

Answer 6

common in parasites
mature mRNA doesn’t correspond to DNA sequence

addition or deletion of uridine to mRNA
deamination of A to give I
deamination of C to give U

Question 7

How do UTRs control mRNA stability?

Answer 7

protein sits in cell membrane and involved in uptake
regions in 3’ untranslated region; combine to iron response protein

changes shape, mRNA degraded

can also affect levels of translation

Question 8

What is RNAi?

Answer 8

mediates resistance to parasitic and pathogenic nucleic acids
regulates expression of protein-coding genes
involved in gene silencing

Question 9

How does RNAi gene silencing work?

Answer 9

1. double stranded RNA chopped up & small pieces associated with protein
2. one strand strips away & base pair by complementary base pairing

just replacing the one strand with th eRNAi by complementary gene pairing

Question 10

What are miRNAs?

Answer 10

regulate gene expression by blocking translation of specific mRNAs
cause their degradation

Question 11

How do mRNAis work?

Answer 11

Transcribed by RNA polymerase 2
1. crop off the ends on the nucleus
2. cleave the loop in the cytoplasm
3. one strand is also degraded
4. RISC matches and then alters expression

Question 12

Why is miRNA regulation important?

Answer 12

involved in fine tuning of genes
key regulators in many biological processes

Question 13

What is gene knockdown?

Answer 13

useful in the labs
can add miRNA to an organism & target specfic genes to reduce them

Question 14

How can RNAi be used as a tool to control infectious disease?

Answer 14

By oral administration
potential use of dsRNA to control viral diseases in farmed shrimp
through intramuscular administration

Question 15

How can RNA be used in medicine?

Answer 15

to treat transthyretin-mdeiated amyloidosis