Unit 1.2 - Proteins

Question 1

What is the proteome?

Answer 1

The entire set of proteins expressed as the genome

Question 2

Why is the proteome larger than the genome?

Answer 2

Because more than one protein can be produced from a single gene due to alternative RNA splicing

Question 3

Name two factors that can affect the set of proteins

Answer 3

Cellular stress and metabolic activity

Question 4

What are the genes that do not code for proteins called?

Answer 4

Non-coding RNA genes

Question 5

What is the role of the Golgi Apparatus?

Answer 5

Transport and modification of proteins

Question 6

What are lysosomes?

Answer 6

Membrane-bound organelles that digest proteins

Question 7

What is the difference between the smooth and rough ER?

Answer 7

The rough ER has ribosomes on its surface while the smooth ER lacks ribosomes

Question 8

Where are lipids synthesised?

Answer 8

The smooth ER

Question 9

What is a signal sequence?

Answer 9

A short stretch of amino acids at one end of the polypeptide

Question 10

What do vesicles move along to get to other membranes?

Answer 10

Microtubules

Question 11

What is proteolytic cleavage?

Answer 11

Another type of post-translational modification

Question 12

What two proteins require proteolytic cleavage to become active?

Answer 12

Digestive enzymes and insulin

Question 13

Describe a ‘“basic” amino acid R group.

Answer 13

• Positively charged

- Amine group (NH₂)

Question 14

Describe an ‘“acidic” amino acid R group

Answer 14

• Negatively charged
• Hydrophilic
• Carboxylic acid group (COOH)

Question 15

Describe a ‘“hydrophobic” amino acid R group

Answer 15

• Non-polar

- Hydrocarbon group (CH₃)

Question 16

Describe a ‘“polar” amino acid R group

Answer 16

• Hydrophilic

- Carbonyl (C=O), hydroxyl (OH) or amine (NH) groups

Question 17

What is the primary structure?

Answer 17

The sequence in which the amino acids are joined to make a protein during synthesis

Question 18

What makes a secondary structure?

Answer 18

Hydrogen bonding along the backbone.

Question 19

Describe an alpha helix

Answer 19

• Formed by twisting the polypeptide chain into a helix

- Stabilised with hydrogen bonding

Question 20

Describe a beta-pleated sheet

Answer 20

• Arranged in rows

- Stabilised with hydrogen bonding

Question 21

Describe turns

Answer 21

Reverse the direction of the polypeptide chain

Question 22

What stabilises a tertiary structure?

Answer 22

Interactions between R-groups

Question 23

Describe a disulfide bridge

Answer 23

Covalent bonds between R-groups

Question 24

Describe ionic bonds

Answer 24

Between positive and negative residues

Question 25

Describe electrostatic interactions

Answer 25

Van der Waals

Question 26

What are interactions of R groups influenced by?

Answer 26

Temperature and pH

Question 27

Where do allosteric interactions take place?

Answer 27

Spatially distant parts of a protein

Question 28

Describe cooperativity

Answer 28

The binding of a substrate in one active site that can alter the affinity of other sites

Question 29

What effect do temperature and pH have on oxygen delivery and affinity of haemoglobin for oxygen

Answer 29

• An increase in oxygen delivery

- A decrease in affinity of haemoglobin for oxygen

Question 30

What changes in temperature and pH affect haemoglobin?

Answer 30

An increase in temperature and a decrease in pH