8.1 Metabolism

Question 1

Types of metabolic pathways

Answer 1

1. Chains: glycolysis
2. Cycles: Krebs

Question 2

Types of enzymatic reactions

Answer 2

1. Catabolic: free E released - exergonic
2. Anabolic: E used - endergonic

Question 3

Types of enzyme inhibition

Answer 3

1. Reversible
2. Irreversible

Depends on inhibitor

Question 4

types of enzyme inhibitors

Answer 4

1. Competitive: same active site as substrate
2. Non-competitive: different active site to substrate

Question 5

Competitive inhibition

Answer 5

• binds to substrate’s active site
• inhibitor chemically/syructurally similar to substrate
• inhibitor’s effect can be decreased by increaseing substrate conc - likelihood od substarte binding instead of inhibitor increases

Question 6

Non-competitive inhibitor

Answer 6

• inhibitor binds to another site - allosteric site - not substrate active site
• allosteric inhibitions leads to conformational enzyme changes - active site altered - substarte acnnot bind
• increasing substrate conc would not decrease inhibitor effect

Question 7

example of competitive inhibitor

Answer 7

Relenza drug - treat influenza virus

relenza competitively binds to neuraminidase active site - prevents docking proteins of virus - cells not infected

Question 8

example of non-competitive inhibitor

Answer 8

Cyanide (CN) - poisonous

CN bonds to allosteric site in cytochrome oxidase in respiration - no longer pass e to final e acceptor O₂ - electron transport chain cannot operate - cell dies

Question 9

Explain feedback inhibition

Answer 9

Feedback inhibition (end-product inhibition): product binds to allosteric site reversibly - reaction halted - product levels drop - detach from allosteric site - recation procedes

Question 10

Example of feedback inhibition

Answer 10

Threonine - osoleucine pathway (plants, bacteria): isoleucine synthesied from threonine - too much produced - inhibits production by binding to allosteric site in enzyme 1 - inhibition allows for both isoleucine and threonine exist in organism

Question 11

Effects of different inhibitors in enzyme kinetics

Answer 11

Vmax can be reached with competitive inhibitor if conc of substrate is increased to high levels

Question 12

Explain rational drug design vs screening in bioinformatic databases for Malaria treatment

Answer 12

Malaria caused by Plasmodium - two life cycles of Plasmodium - both in mosquito and human - development of parasite dtermined by enzymes - if inhibited - prevented from development

In bioinformatic databases potentail inhibitors are screend for parasitic enzyme inhibition - high efficinecy of finding a fit

_Rational drug desig_n (another method) - using computers to invent a chemical which would act as an inhibitor (anti-malarial drugs)

Question 13

The accepted model of enzymes

Answer 13