Session 9 no protein targeting yet!!(Protein Processing And Targeting)

Question 1

Name the 2 types of processing

Answer 1

Proteolytic cleavage (breaking)
Covalent modification (adding groups)

Question 2

What happens to proteins made on free ribosomes?

Answer 2

They stay in the cytosol/go into organelles

Question 3

What happens to proteins made on RER ribosomes?

Answer 3

They go to the membrane or secretory pathways

Question 4

What is needed for protein sorting?

Answer 4

Signalling sequence
Receptor
Translocation machinery
Energy

Question 5

What do membrane proteins have within their sequences?

Answer 5

Stop-transfer anchor sequence

Question 6

In terms of secretory proteins, what does SRP stand for?

Answer 6

Signal recognition particle

Question 7

List the functions of the ER (7)

Answer 7

Assembly of multi subunit proteins 
Hydroxylation of selected Lys and Pro residue 
Glycosylation
Forms S-S bonds
Proper folding of proteins
Specific Proteolytic cleavage 
Insertion of proteins into membranes

Question 8

What is used to protect nascent proteins?

Answer 8

Chaperone proteins (which can correct problems in structure)

Question 9

What is glycosylation?

Answer 9

Adding a carbohydrate to a molecule

Question 10

Describe the processing of production insulin from pre-proinsulin (3)

Answer 10

(Entering ER)- signal peptide cleaved - proinsulin
(In ER lumen)- disulphides bridges are formed -proinsulin
(In GA)- introns removed (B chain)- insulin