Post translational modification

Question 1

this ensures that polypeptides will be delivered to the correct place

Answer 1

zip code

Question 2

compartments of eukaryotic alls

Answer 2

-Endomembrane system
-cytosol
- Mitochondria, chloroplast ,periposome, and interior of nucleus

Question 3

where does translation usually takes place?

Answer 3

-ribosomes

Question 4

why are the ribosome residing inside the nucleus

Answer 4

10% ribosome in nucleus
why? BC they get orders of protein synthesis (their main function) in the nucleus

Question 5

Explain Pathway A for directing the newly synthesized polypeptide

Answer 5

1. Ribosomes attached to the endoplasmic reticulum (ER) synthesizes polypeptides
2. Cotranslational import- transfer of polypeptide into Er as synthesis continues
3. Proteins transport to final destination via membrane vesicle and Golgi complex

Question 6

Explain pathway B for directing polypeptide into target location

Answer 6

1. Polypeptide will be released in ribosome after translation
2. Post translational import is necessary for organelle uptake (as it relies on unique targeting signals
3. Polypeptide enter the nucleus through nuclear pore

Question 7

what happens in the cotranslational translocation

Answer 7

the ribosome in the ER synthesizes the protein destined for either the endomembrane system of secretion.

During this process the growing nascent polypeptide chain is inserted in the pore within er membrane, inside they will pass through the lumen as they are being synthesized in the ribosome, allowing them to be routed to their correct destination

Question 8

what is the sequence that guides the ribosome mRNA polypeptide complex to the surface of the RER

Answer 8

ER signal sequence

Question 9

How long is the ER signal sequence
now many domains
what is the charge of the A terminal region and central region

Answer 9

15-30 amino acid long
3 domains
positive and central hydrophobic region

Question 10

what are the 3 birding domains a signal Recognition particle (SRP)

Answer 10

1. birds to the signal sequence as soon as it is translated
2. birds to ribosome, stopping translation
3. birds to SRP receptor in ER membrane near sec61

Question 11

what does the sec 61 do

Answer 11

A translocon that imports the protein into the ER