week 5 - vesicular trafficking - cell compartmentalisation

Question 1

What do nuclear pore complexes do?

Answer 1

Involved in moving substances across the nuclear envelope.

Question 2

What is the nuclear envelope?

Answer 2

it is a double membrane which surrounds the nucleus

Question 2

What is the nuclear envelope?

Answer 2

it is a double membrane which surrounds the nucleus

Question 3

By which 2 process can substances be transported by the pore complex?

Answer 3

Diffusion and active transport.

Question 4

Newly made proteins can be translocated into organelles either co or post tranlationally. What do these mean?

Answer 4

Co-translational translocation = the protein is being translated (made on the ribosome) and simultaneously being translocated across the membrane

Post-translational translocation = after protein is synthesised in the cytosol, it is then transported across the membrane.

Question 5

What is the role of chaperones in the ER?

Answer 5

they ensure there is proper protein folding.

Question 6

How do you get proteins into mitochondria?

Answer 6

N-terminal signal sequence - recognised by the TOM complex.

1. Insertion into membrane by TOM complex.
2. The protein translocates through TOM and TIM23.
3. Translocates through TIM23 into the matrix.
4. signal is cleaved off.