A1

Question 1

What is a typical characteristic of a eukaryotic cell?

Answer 1

it has a complex cytoskeleton

Question 2

How is the ER translocation channel opened to allow the nascent protein to move through it?

Answer 2

The binding of the signal sequence to the Sec61 translocation channel

(mod. 1.7 + ER targeting and translocation movie)

Question 3

The principal advantage of the green fluorescent protein is what?

Answer 3

It can be used in living cells

Question 4

The [x] hypothesis suggests that mitochondria have evolved from ancient prokaryotes. This is supported by the fact that mitochondria have their own circular genome and their [z] resemble the 70S ones found in bacteria rather then the 80S ones of the eukaryotic cytosol.

Answer 4

x = endosymbiotic
z - ribosomes

Question 5

What effect does SRP (signal recognition particle) binding to the ribosome nascent chain complex have on protein synthesis?

Answer 5

There is a slowing down of translation whilst SRP is bound.

Question 6

Three statements of cell theory

Answer 6

• All living organisms are composed of one or more cells.
• The cell is the basic unit of structure and organization in organisms.
• Cells arise from pre-existing cells.

Question 7

Which amino acids would you expect to find in a typical ER targeting signal?

Answer 7

Valine and tryptophan
Leucine and alanine
Isoleucine and phenylalanine

Question 8

What is the typical fate of an N-terminal ER signal sequence after it has successfully targeted a protein to the Sec61 translocator in the ER?

Answer 8

The signal sequence is cleaved by a protease enzyme and removed from the protein