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Flashcards in Chapter 3 Deck (4):
1

Enzymes

• Biological catalysts that speed up the rate of chemical reactions by bringing two substrates together
• Operates continuously to maintain cellular processes essential for life occur at rates sufficiently fast to maintain the living state
• Proteins that consist of one or more polypeptide chains (monomeric and oligomers)
• Have an active site which is complementary and specific to a substrate, functional group or side chain, or for a bond between particular groups
• Denaturation of enzymes affects H bonds (secondary structure) alters active site and cannot temporarily or permanently function
• Some are inactive proenzymes, and are activated in response to signals

2

Metabolism

Metabolism- chemical reactions that are taking place in living organisms
Catabolism- cellular reactions that releases useful energy from the breakdown of complex molecules (exergonic)
Anabolism- cellular reactions in which the complex molecules required by cells are synthesised from simpler building blocks, a process that requires an input of energy (endergonic)

3

Factors affecting enzymes

Temperature (inactivates or denatures, covalent bonds), enzyme concentration, pH (optimum pH), substrate concentration affects enzyme activity

4

Enzyme inhibitor

a molecule that binds to an enzyme and interferes with it, limiting its activity
Irreversible inhibition- when a molecule covalently bonds to amino acid/s and alters the enzyme structure (poisons)
Reversible inhibition- inactivates enzymes through noncovalent bonds (competitive where the inhibitor has a similar shape of the substrate, and non-competitive where the inhibitor binds to the allosteric site and distorts the 3D shape of the enzyme)
End-product inhibition- where the end product (B) of the metabolic pathway inhibits the production of the first enzyme in the pathway, inhibitor goes away when the concentration of product B increases