Unit 1: Proteins

Question 1

What is the proteome?

Answer 1

The proteome is the entire set of proteins expressed by a genome

Question 2

Why is the proteome larger than the number of genes?

Answer 2

Because more than one protein can be produced from one gene as a result of alternative gene splicing

Question 3

What is the endoplasmic reticulum?

Answer 3

A network of membrane tubules continuous with the nuclear membrane

Question 4

What is the Golgi apparatus?

Answer 4

The Golgi apparatus is a series of flattened membrane discs

Question 5

What are lysosomes?

Answer 5

Lysosomes are membrane-bound organelles containing a variety of hydrolases that digest proteins, lipids, nucleic acids and carbohydrates

Question 6

What are vesicles used for?

Answer 6

Vesicles transport materials between membrane compartments

Question 7

What is the difference between the SER and the RER?

Answer 7

The RER has ribosomes on its cytosolic face while the SER lacks ribosomes

Question 8

What is synthesised in the SER?

Answer 8

Lipids which are then inserted into its membrane. The synthesis of all proteins begins in cytosolic ribosomes.
The synthesis of cytosolic proteins is completed in the SER, and these proteins remain in the cytosol

Question 9

What is synthesised in the RER?

Answer 9

Proteins

Question 10

What is a signal sequence?

Answer 10

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

Question 11

Why can eukaryotic cells not carry out all the vital functions of the cell membranes?

Answer 11

Because of their size, eukaryotes have a relatively small surface area to volume ratio. The plasma membrane of eukaryotic cells is
therefore too small an area to carry out all the vital functions carried out by membranes.