1i- Synthesis of membrane components

Question 1

Where are lipids and proteins synthesised?

Answer 1

In the ER (endoplasmic reticulum)

Question 2

What is the difference between the Rough ER (RER) and the smooth ER (SER)?

Answer 2

The rough ER (RER) has ribosomes on its cytosolic face whilst the smooth ER (SER) lacks ribosomes

Question 3

Where are lipids synthesised?

Answer 3

The smooth endoplasmic reticulum (SER) and are then inserted into its membrane

Question 4

Where does the synthesis of all proteins begin?

Answer 4

In cytosolic ribosomes

Question 5

Where is the synthesis of cytosolic proteins completed?

Answer 5

In cytosolic ribosomes, these proteins remain in the cytosol

Question 6

What do transmembrane proteins do?

Answer 6

They carry a signal sequence, which halts translation and directs the ribosome synthesising the protein to dock with the ER, forming the rough ER. Translation then continues after docking, and the protein is inserted into the membrane of the ER

Question 7

What is a signal sequence?

Answer 7

A short stretch of amino acids at one end of the polypeptide that determines the eventual location of a protein in a cell