Translation

Question 1

Translation in ribosomes

Answer 1

Ribosomes have a large subunit and small sub

mRNA is sandwiched between them

Aminoacyl binding site (A site) (AUG)
Peptide binding site (p site)
E site

Question 2

A cite

Answer 2

Incoming tRNA carrying the amino acid binds here on mRNA

Question 3

P site

Answer 3

Site where amino acid chain is built

Question 4

E site

Answer 4

Where tRNA exits the ribosome

Question 5

Initiation of translation

Answer 5

Ribosomes recognize 5’ cap and the start codon (met)

Ribosome reads mRNA in 5-3 direction adding a new amino acid for each codon read

Question 6

tRNA in translation

Answer 6

tRNA delivers the correct amino acid to the protein building site on the ribosome

tRNA resembles a 4 leaf clover

Each tRNA is attached to an amino acid

Question 7

tRNA structure

Answer 7

Anticodon- arm of the molecule recognizes the codon on mRNA

Accepter arm- carries corresponding amino acid

The 3rd base in each codon is flexible- allowed aa to be added despite mRNA errors
Ex. AA tyrosine =mRNA codon UAU or UAC-> codon can bind to both b/c wobble

Question 8

Termination of translation

Answer 8

Ribosome reaches stop codon

Release factor = protein that helps ribosome release polypeptide (sandwich falls apart)

2 ribosomal subunits fall of mRNA

Protein folds into 3-D in area of cell where it’s needed

Question 9

Modifications

Answer 9

Sugars and phosphates may be added to some amino acids, depends on functions

Some enzymes may cleave (cut) chain at specific spots Rx. Insulin-> synthesized as preprounsulin which cleaves, then becomes proinsulin which cleaves, becomes insulin

Question 10

How does translation start?

Answer 10

mRNA enters the cytoplasm and is ready for translation into protein by the ribosomes