Lecture 21: Summary of central dogma

Question 1

In eukaryotes:
rRNA is synthesised by?
mRNA is synthesised by?
tRNA is synthesised by?

In prokaryotes
A single what synthesised all types of RNA?

Answer 1

In eukaryotes:
rRNA is synthesised by? RNA polymerase 1
mRNA is synthesised by? RNA polymerase 2
tRNA is synthesised by? RNA polymerase 3

In prokaryotes
A single what synthesised all types of RNA?
RNA polymerase

Question 2

DNA is read in what direction
mRNA is synthesised in what direction
mRNA is read in what direction?
What is the first codon that codes for methionine
Proteins are synthesised NH2 terminus –> COOH terminus

Answer 2

DNA is read in what direction? 5’ -> 3’
mRNA is synthesised in what direction 3’–> 5’
mRNA is read in what direction? 5’ –> 3’ direction
What is the first codon that codes for methionine? AUG
Proteins are synthesised NH2 terminus –> COOH terminus

Question 3

Say you started of with a non-template DNA reading 3’ to 5’ what next?

Answer 3

Must convert it to a template DNA 5’ to 3’
Then to 3’ to 5’ template strand
Then synthesis mRNA 5’ to 3’
Refer to slide 3

Question 4

Inhibitors of transcription

Answer 4

Binding of inhibitor to the DNA prevents the DNA from acting as a template for RNA synthesis.
What is this inhibitor?
What is the inhibitor that blocks the action of RNA polymerase?
a-amanitin: from a poisonous mushroom which blocks RNA polymerase 2
Rifampicin:
-potent inhibitor of prokaryotic RNA polymerase which acts as a useful pro biotic

Question 5

Inhibitors of translation:

Answer 5

A large number of components can inhibit the process because its quite complex.
Eg tetracyclins, streptomycin and erythromycin primarily effect Bactrian cells. They are thus useful antibiotics
Eg chloramphenicol
-inhibits prokaryotic peptidyl transferase
-also a useful antibiotic