Unit 1 - Key Area 2: Proteins

Question 1

What is the proteome?

Answer 1

The entire set of proteins expressed by the genome

Question 2

Describe alternative RNA splicing

Answer 2

The process by which different exons are spliced from the primary transcript to produce different mature RNA transcripts.

Question 3

Describe the structure of the rough endoplasmic reticulum

Answer 3

Network of membrane tubules, studded with ribosomes that facilitate translation of non-cytosolic proteins.

Question 4

Describe the structure of the Golgi apparatus

Answer 4

A series of flattened membrane discs involving in post-translational modification of proteins

Question 5

Describe the structure of Lysosomes

Answer 5

Membrane-bound organelles containing hydrolyases that digest proteins, nucleic acids, lipids and carbohydrates.

Question 6

Describe the structure of Vesicles

Answer 6

Important membrane-bound organelles within the secretory pathway that transport proteins through the cytosol.

Question 7

Describe the function of the smooth endoplasmic reticulum

Answer 7

Site of lipid synthesis

Question 8

What is the role of cytosolic ribosomes?

Answer 8

Where ALL proteins BEGIN their translation journey.

Question 9

Describe what is meant by the signal sequence of a polypeptide

Answer 9

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

Question 10

Give some examples of post-translational modification

Answer 10

Takes place in the Golgi and includes addition of phosphate, carbohydrates, methyl groups or even the cutting and joining of polypeptide chains.

Question 11

Give some examples of secreted proteins

Answer 11

digestive enzymes (e.g. amylase) and peptide hormones (e.g. insulin).

Question 12

Explain why eukaryotic cells need to have separate membrane bound organelles

Answer 12

Increases the total area of membrane available for vital metabolic processes

Question 13

Name the components of cellular membranes

Answer 13

Phospholipids & Proteins

Question 14

Primary structure

Answer 14

Amino acid sequence

Question 15

Tertiary structure

Answer 15

The overall shape of a protein molecule due to interactions of amino acid side chains, including hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.

Question 16

Secondary structure

Answer 16

Alpha helices, beta pleated sheets and turns

Question 17

Quaternary structure

Answer 17

The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits.

Question 18

Prosthetic group

Answer 18

A non-protein, but organic, molecule (such as vitamin) that is covalently bound to an protein and is necessary for its function

Question 19

R group

Answer 19

Variable side chain of an amino acid

Question 20

Peptide bond

Answer 20

Bond between two amino acids

Question 21

Ligand

Answer 21

A molecule that binds to a protein

Question 22

Allosteric site

Answer 22

A site distinct from the active site, found on an enzyme molecule.

Question 23

Modulators

Answer 23

Regulate the activity of an enzyme when they bind to the allosteric site.

Question 24

Cooperativity

Answer 24

Often observed in proteins with quaternary structure where binding of a ligand to one subunit alters the affinity of the remaining subunits for the ligand.

Question 25

Phosphorylation

Answer 25

A form of post-translational modification that proteins can undergo.

Question 26

Kinases

Answer 26

A class of enzymes that catalyse phosphorylation of proteins.

Question 27

Phosphatases

Answer 27

A class of enzymes that catalyse the dephosphorylation of proteins.