Enzymes Model Answers Revision

  • Created by: ElishaG
  • Created on: 24-03-17 17:59
Explain the term biological catalyst.
1)Enzymes are proteins used in metabolism.2)They alter the rate of chemical reactions by lowering the activation energy for a reaction and are not changed or used up during the reaction.
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Lock and Key and induced fit theory are both 'models', what is meant by the term 'model'?
1)A simple representation of the process and structure.2)Visual representation showing people how it works.
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Describe the induced fit theory of enzyme action.
1)Substrate binds to active site.2)Active site shape changes-closer fit between active site and substrate.3)More bonds form between substrate and active site.4)Forms enzyme/substrate complex.5)Change in shape of active site.6)Activation energy lower.
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Describe the lock and key theory of enzyme action.
1)Substrate has complementary shape and charge to active site.2)Substrate binds to active site and forms an enzyme-substrate complex.3)Substrate converted to product.4)Product no longer complementary in shape and charge and so is released.
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What is meant by the term intracellular enzyme?
1)An enzyme that is found/catalyses reactions in the cytoplasm of a cell.2) e.g. DNA polymerase,DNA helicase,RNA polymerase,carbonic anhydrase.
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What is meant by the term extracellular enzyme?
1)An enzyme that is found/catalyses reactions outside of a cell.2)e.g. digestive enzymes in small intestine, lipase, amylase.
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What is meant by enzyme specificity?
1)Enzymes can only catalyse one type of reaction.2)Active site is complementary to one type of substrate.3)e.g. amylase has active site complementary to starch.
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Explain why different enzymes are involved in each stage of the digestion process?
1)Enzymes are specific.2)Substrates are different shapes.3)Active site and substrate are complementary.4)So that substrate will fit and form an enzyme/substrate complex.5)Lock and key/induced fit.
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Explain why the activity of enzymes decreases above/below optimum PH.
1)PH higher- less acidic than optimum due to OH-..2)PH lower-less alkaline than optimum due to H+.3)Change in charge of active site.4)Hydrogen/Ionic bonds break.5)Tertiary structure altered.6)Enzyme denatured.7)Substrate no longer fits.
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Explain why the activity of enzymes decreases below optimum temperature.
1)Enzyme and substrate molecules lack kinetic energy.2)Move more slowly.3)Less chance of successful collisions.4)Activation energy not met.5)Fewer enzyme-substrate complexes form.6)Less product formed per second.
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Explain why the activity of enzymes increases above optimum temperature.
1)Enzyme and substrate molecules gain kinetic energy.2)Move more quickly.3)Increased chance of successful collisions.4)Activation energy met.5)More enzyme-substrate complexes form.6)More product formed per second.
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Explain the effect of increasing the concentration of substrate on rate of reaction.
1)More substrate molecules enter active site.2)More enzyme-substrate complexes form.3)At low conc. not all active sites occupied.4)At high conc. all active sites occupied.5)Reaches max turnover rate (Vmax).
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At high substrate concentration, what is the limiting factor?
Enzyme concentration.
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Explain the effect of increasing the concentration of substrate on rate of reaction in the presence of a competitive inhibitor.
1)Inhibitor can bind to/compete for active site.2)Occupies it reversibly for a short time.3)Fewer active sites available for substrate.4)More substrate reduces chance of inhibitor getting in.
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Describe how non-competitive inhibitors effect rate of reaction.
1)Rate decreases.2)Fits into allosteric site,3)Active site changes.4)Substrate no longer complementary to active site.5)Enzyme/substrate complex doesn't form.
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Describe how competitive inhibitors effect rate of reaction.
1)Rate decreases.2)Inhibitor and substrate have similar shape.3)both will fit into enzymes active site-complementary.4)Substrate molecules blocked from entering active site.5)Fewer enzyme-substrate complexes form.
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Explain why the initial rate of reaction is always faster.
1)More substrate molecules initially.2)More substrate molecules enter active site.3)More enzyme-substrate complexes formed.4)As reaction progresses, fewer substrate molecules.5)Less chance of successful collisions.6)Fewer enzyme-substrate complexes.
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Card 2

Front

Lock and Key and induced fit theory are both 'models', what is meant by the term 'model'?

Back

1)A simple representation of the process and structure.2)Visual representation showing people how it works.

Card 3

Front

Describe the induced fit theory of enzyme action.

Back

Preview of the front of card 3

Card 4

Front

Describe the lock and key theory of enzyme action.

Back

Preview of the front of card 4

Card 5

Front

What is meant by the term intracellular enzyme?

Back

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