Metabolism - extra

Question 1

Which amino acids are always protonated?

Answer 1

Arginine and lysine

Question 2

Which amino acids are always negatively charged?

Answer 2

Glutamate and aspartate

Question 3

What are the 6 hydrophilic side-chained amino acids?

Answer 3

Season Three’s Tyrion Acquired a Giant Cyst

Serine, Threonine, Tyrosine, Asparagine, Glutamine, Cysteine

Question 4

Which group is normally on the right of the carbon in an amino acid?

Answer 4

The carboxyl group.

Question 5

How can electrophoresis be used to measure changes in DNA sequences (mutations)?

Answer 5

A change in DNA (even small point mutations) will induce a slight change in charge which will effect the migration rate of the protein in electrophoresis, separating it from its un-mutated protein.

Question 6

Which bonds are involved in tertiary structure of proteins?

Answer 6

• Hydrogen bonds
• Ionic interactions
• Hydrophobic interactions
• Disulphide bridges

Question 7

What bonds stabilise alpha helices and beta-pleated sheets?

Answer 7

Hydrogen bonds

Question 8

How are bonds distributed in alpha helices and beta-pleated sheets?

Answer 8

Alpha - between N-H and C=O every 4 amino acids apart

Beta - between N-H and C=O between two or more beta strands

Question 9

What is Gibbs free energy?

Answer 9

The amount of energy within a molecule that is able to perform useful work at a constant temperature. If it is negative, the reaction is spontaneous. Measured in kJ/mol.

Question 10

Why is ATP hydrolysis good for a coupled reaction?

Answer 10

ATP has phosphoanhydride bonds with a large negative Gibbs free energy value, meaning they are high energy bonds.

Question 11

In respect to entropy, where will a spontaneous reaction proceed towards?

Answer 11

Towards products with a greater entropy.

Question 12

What is Km?

Answer 12

The value of substrate at half maximum velocity (half of the active sites are occupied).

• Independent of substrate concentration
• Constant for an enzyme
• The smaller the Km, the higher the affinity of the substrate for the enzyme.

Question 13

What is Vmax?

Answer 13

The maximum velocity of an enzyme at which all the active sites are occupied.

Question 14

How do you calculate Km?

Answer 14

Km = 1/2(Vmax)

Question 15

How is Km and Vmax affected by a competitive inhibitor?

Answer 15

Vmax is unchanged but Km is increased.

Question 16

How is Km and Vmax affected by a non-competitive inhibitor?

Answer 16

Vmax is not met but Km is unchanged as the ability to bind is not altered, just some active sites are permanently ‘poisoned’.

Question 17

How do vesicles move through cells?

Answer 17

Short distance - diffusion

Long distance - cytoskeleton-based motor proteins

Question 18

What does NADH accept?

Answer 18

1 proton and 2 electrons

Question 19

What is a coenzyme?

Answer 19

Binds to enzymes and assists in enzymatic activity. They are not specific to a certain enzyme but will only function after binding to an enzyme).

Question 20

What is NADH important for?

Answer 20

Dehydrogenase reactions.

Question 21

What are endosomes?

Answer 21

Membrane-bound organelles similar to temporary vesicles used for transportation.

Question 22

What is the different between early, recycling and late endoscopes?

Answer 22

Early - involved in the sorting of ligands and receptors into different compartments.
Recycling - receive internalised material from early endoscopes and direct to cell surface or Golgi
Later - derived from vesicular parts of early endosomes and are tasked with managing receptors not suitable for recycling. Prepare them for lysosomal degradation by fusing with lysosomes.

Question 23

How is a spectrophotometer used to measure enzyme activity?

Answer 23

Measures the amount of light absorbed by a substrate. Can measure the production of a substrate or the use up of a substrate but analysing changes in light absorption.

Question 24

What is GTP used for?

Answer 24

Can be used as an energy source but mainly involved in cell signalling.

Question 25

Another name for co-enzyme Q?

Answer 25

Ubiquinone

Question 26

How many molecules of ATP do anaerobic and aerobic respiration produce?

Answer 26

Anaerobic - 2

Aerobic - 38

Question 27

What does FADH2 donate?

Answer 27

2 electrons and 2 protons

Question 28

What is ACAT?

Answer 28

An intracellular enzyme that works on cholesterol once it is taken up into a cell by endocytosis.

Question 29

What differs between the different classes of lipoproteins?

Answer 29

Form of apoprotein found in them - allows recognition by different cell types.

Question 30

What enzyme is used to catalyse the formation of cholesterol esters?

Answer 30

Lethicin cholesterol acyltransferase (LCAT)

Question 31

How do resins/sequestrants work?

Answer 31

Bind to bile acid-cholesterol complexes and prevent their reabsorption into the small intestine, reducing LDL levels and increasing HDL levels.

Question 32

What is the difference between glycolysis and gluconeogenesis?

Answer 32

Glycolysis takes place in cytoplasm and gluconeogenesis takes place in the liver specifically.
Gluconeogenesis also does not produce acetyl-coA or pyruvate.

Question 33

How many ATP molecules are used in gluconeogenesis?

Answer 33

6

Question 34

What does the R group of an amino acid change?

Answer 34

The chemical properties of the amino acid.