Translation

Question 1

What is the central dogma in molecular genetics?

Answer 1

DNA is transcribed into RNA which is translated into protein.

Question 2

Translation definition

Answer 2

The process in which ribosomes in the cytoplasm or endoplasmic reticulum synthesise proteins.

Question 3

Codon definition

Answer 3

Triplet base on mRNA that binds to one complementary anticodon on the tRNA

Question 4

Start codon and amino acid it codes for

Answer 4

AUG- methionine

Question 5

Features of the genetic code

Answer 5

Degenerate- several triplets for a particular amino acid
non-overlapping- can only be read once
universal- present in all organisms

Question 6

How many reading frames are there?

Answer 6

3, depending on where the decoding process begins

Question 7

Where does protein synthesis take place + how is it initiated?

Answer 7

Ribosome- binds to the mRNA molecule near the 5’ end.

Question 8

How does translation occur at the ribosome?

Answer 8

Small subunit scans mRNA for AUG sequence, then binds. Large subunit then joins.

Translation begins, mRNA passed through the ribosome three nucleotides at time where the tRNA adopters bind and allow their attached amino acids to bind to each other.

When a stop codon is encountered the ribosome releases the finished protein and its two subunits separate again.

Question 9

How many amino acids are added per second?

Answer 9

2

Question 10

Different sites at ribosome and function

Answer 10

E site- Exit site where the tRNA molecules leave
P site- Peptidyl site- occupied by methionine initiator tRNA
A site- contains next tRNA and its codon below it

Question 11

3 stages of translation

Answer 11

initiation- ribosome assembles around the target mRNA and first tRNA attaches to start codon
elongation- tRNA transfers an amino acid to the tRNA at the adjacent codon
termination- when a peptide tRNA encounters a stop codon

Question 12

Explain wobble hypothesis

Answer 12

Some tRNAs can recognise more than one codon. The tRNAs usually differ in the third base.
Base pairing of the third codon to anticodon (at the wobble position) is less strict and can base pair with more than one complementary base.

Question 13

Cap and Poly A tail functions in relation to translation

Answer 13

Cap binding proteins and proteins that bind the Poly A tail interact with each other to create a circular mRNA molecule that recruits the ribosome to the mRNA

Question 14

signal hypothesis

Answer 14

proteins aimed for secretion are modified with extra amino acids, which do not occur in the final secreted protein

allow movement through membrane