E4

Question 1

Names Of protein complex’s

Answer 1

Monomer
Dimmer (homodimmer or heterodimer)
Trimmer
Tatramer
Multimer

Question 2

Haemoglobin and myoglobin

Answer 2

Are oxygen transport and storage proteins

Question 3

Haemoglobin

Answer 3

Transport oxygen in blood

Question 4

Myoglobin

Answer 4

Stores oxygen in muscles

Question 5

Myoglobin + haemoglobin

Answer 5

Myoglobin is monomeric and a single polypeptide chain Of 153 amino acids to form 8 alpha helices
Haemoglobin is tetrameric made up of 4 polypeptide chains 2 alpha chains 141 amino acids 2 beta chains of 146 amino acids each fold to form 8 alpha helix’s

Question 6

Who has more affinity to oxygen

Answer 6

Myoglobin

Question 7

Explain how haemoglobin is an allosteric protein

Answer 7

Binding of oxygen to one subunit causes a conformational change from a tense to a relaxed state and increase ease of binding of oxygen to other subunit

Question 8

Explain how haemoglobin is an allosteric protein

Answer 8

Binding of oxygen to one subunit causes a conformational change from a tense to a relaxed state and increase ease of binding of oxygen to other subunit

Question 9

Confirmation change

Answer 9

Without oxygen bound fe2+ is out of the heam plate oxygen binding pulls the fe2+ into the heam plane
Binding of oxygen also pulls the F8 ligand and the F helix
This change has a big impact on haemoglobin helping other subunits bind oxygen

Question 10

Ph and Bohr effect

Answer 10

Binding of proteins by haemoglobin lowers affinity for oxygen contributing to a phenomenon known as boher effect
The Ph of the blood decreases as it enters the tissues because the co2 produced by metabolism is converted to carbonic acid by the reaction catalysed in red blood cells
Dissociation of carbonic acid produces protons that react with several amino acid residues in haemoglobin, causing conformational changes that promote the release of oxygen

Question 11

What are the varieties Of proteins function

Answer 11

Structural proteins from the cytoskeleton
Transport and store molecules
Enzymes catalyse biochemical reactions
Membranes transport proteins
Regulatory and signalllling proteins
Motor proteins move intracellular complexes

Question 12

Enzymes

Answer 12

Enzymes,es lower the energy of the transition state of a chemical reaction
Work under physiological conditions
Very highly specific
Use functional groups at the active site provided by amino acids and might include coenzymes
Can be regulated to control reaction rates by various mechanisms

Question 13

Thermodynamics

Answer 13

For a reaction to proceed an energy rider needs to be overcome energy is needed to transform substrate molecules into a transition sate can unstable chemical C part way between substrate, and product
Transition state has highest free energy in the reaction
Difference in free energy between the substrate and transition state is termed gibbs free energy of activation
Enzymes stabilizes the transition state and lowers delta G +/-, increasing the rate eat which reaction occurs

Question 14

Vmax and km

Answer 14

Vo = vmax (s)/ km + [5]

Question 15

Binding of substrates to enzymes

Answer 15

Acid-base
Temporary covalent bond formation
Redox effect
Electrostatic effects
Orientation proximity effects and straing effects

Question 16

Cofactors

Answer 16

Non protein molecules that are required for a reaction to take place
Can be organic or inorganic

Question 17

Coenzymes

Answer 17

Cofactors that bind loosely and are chemically altered by the enzymes

Question 18

How are coenzymes distinguished from substrates

Answer 18

Coenzymes are recycled for participating in the same reaction

Question 19

Cofactors that bind tightly

Answer 19

These are considered part of the enzyme

Question 20

Apoenzyme

Answer 20

Enzymes without cofactors

Question 21

Holoenzyme

Answer 21

Enzymes with a cofactor

Question 22

Competitive inhibition

Answer 22

Molecule competes with substrate for the substrate binding site
The reaction can be reversible or irreversible

Question 23

Covalent modification

Answer 23

Chemical modification of amino acid residues
Can lead to increase or decrease to the enzyme activity

Question 24

Allosteric regulation

Answer 24

Non-covalent binding of a molecule to the enzyme that does not directly compete with substrate binding
Forms a confirmation change that affects enzyme activity

Question 25

Regulating enzyme activity

Answer 25

1. competitive inhibition
2. Covalent modification
3. Allosterie regulation
4. Rate slows as product accumulates
5. Rate depends on substrate availability
6. Genetic control
7. Modulator proteins