Topic 8.1 Metabolism Flashcards Preview

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Flashcards in Topic 8.1 Metabolism Deck (13)
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1
Q

Metabolism

A

describes the sum total of all reactions that occur within an organism in order to maintain life

2
Q

Metabolic pathways

A

typically organized into chains or cycles of enzyme-catalyzed reactions

3
Q

Activation Energy

A
  • Enzymes speed up the rate of a biochemical reaction by lowering the activation energy
  • When an enzyme binds to a substrate it stresses and destabilizes the bonds in the substrate
  • This reduces the overall energy level of the substrate’s transitionary state, meaning less energy is needed to convert it into a product and the reaction proceeds at a faster rate
4
Q

If the reactants contain more energy than the products…

A

the free energy is released into the system (exergonic), these reactions are usually catabolic (breaking down), as energy is released from broken bonds within a molecule

5
Q

If the reactants contain less energy than the products…

A

free energy is lost to the system (endergonic)

these reactions are usually anabolic (building up), as energy is required to synthesize bonds between molecules

6
Q

Enzyme Inhibition

A

Enzyme inhibitors prevent the formation of an enzyme-substrate complex and hence prevent the formation of product

7
Q

Normal Enzyme Reaction

A
  • In a normal reaction, a substrate binds to an enzyme (via the active site) to form an enzyme-substrate complex
  • The shape and properties of the substrate and active site are complementary, resulting in enzyme-substrate specificity
  • When binding occurs, the active site undergoes a conformational change to optimally interact with the substrate (induced fit)
  • This conformational change destabilizes chemical bonds within the substrate, lowering the activation energy
  • As a consequence of enzyme interaction, the substrate is converted into product at an accelerated rate
8
Q

Competitive Inhibition

A
  • Competitive inhibition involves a molecule, other than the substrate, binding to the enzyme’s active site
  • The molecule (inhibitor) is structurally and chemically similar to the substrate (hence able to bind to the active site)
  • The competitive inhibitor blocks the active site and thus prevents substrate binding
  • As the inhibitor is in competition with the substrate, its effects can be reduced by increasing substrate concentration
9
Q

Noncompetitive Inhibition

A
  • Non-competitive inhibition involves a molecule binding to a site other than the active site (an allosteric site)
  • The binding of the inhibitor to the allosteric site causes a conformational change to the enzyme’s active site
  • As a result of this change, the active site and substrate no longer share specificity, meaning the substrate cannot bind
  • As the inhibitor is not in direct competition with the substrate, increasing substrate levels cannot mitigate the inhibitor’s effect
10
Q

Examples of enzyme inhibition

A
  • An example of a use for a competitive inhibitor is in the treatment of influenza via the neuraminidase inhibitor, Relenza TM
  • An example of a use for a non-competitive inhibitor is in the use of cyanide as a poison (prevents aerobic respiration)
11
Q

End-product inhibition

A

a form of negative feedback by which metabolic pathways can be controlled

12
Q

End-product inhibition functions

A

to ensure levels of an essential product are always tightly regulated

13
Q

Malaria

A
  • The life cycle of the parasite requires both a human and mosquito host – hence the disease is transmitted via mosquito bites
  • The maturation and development of the parasite in both human and mosquito host is coordinated by specific enzymes
  • By targeting these enzymes for inhibition, new anti-malarial drugs and medications can be produced-