1.7 Enzyme action Flashcards

(14 cards)

1
Q

What is an active site (only use this term for enzymes)

A

*A small part of an enzyme that attaches to a substrate to catalyse a reaction
*It is specific and unique in shape due to the specific folding and bonding in ther tertiary structure of the protein

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2
Q

How do enzymes act as biological catalysts

A

*Each enzyme lowers the activation energy of a reaction
*To speed up the reaction without getting used up
*Provide an alternative pathway with a lower activation energy

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3
Q

What does the Lock and Key model suggest (4)

A
  • The active site is a fixed shape and due to random collisions the substrate can collide and attach to the enzyme
  • forming an ENZYME SUBSTRATE COMPLEX
  • Once they are in the ENZYME SUBSTRATE COMPLEX it will cause the substrate to slightly distort in shape lowering the activation energy
  • After the substrate distorts in shape the products are then released and the active site is empty and ready to be reused
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4
Q

What is the analogy used for in the induced fit

A

The enzyme is a glove and the substrate is your hand

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5
Q

Explain the glove and hand analogy of the inducing fit

A

A glove is not exactly complimentary to your hand but when your hand enters it enables the glove to mold around your hand to become completely complimentary

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6
Q

Describe the induced fit model of enzyme action (4)

A
  1. Substrate binds to (not completely complementary) active site of enzyme
  2. Causing active site to change shape (slightly) so it is complementary to its substrate
  3. So enzyme-substrate complex forms
  4. Causing bonds in substrate to distort, lowering activation energy
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7
Q

Why are enzymes effective in small quantities

A

They can be reused repeatedly

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8
Q

What are the conditions required for a reaction (between enzyme and the substrate) (3)

A
  • Reactants (substrate) must collide with sufficient energy to alter the arrangements of their atoms to form the product
  • The free energy of the products must be less than that of the reactants
  • The activation energy must be reached

Free energy= The energy available in a system to do work

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9
Q

Define activation energy

A

The minimum amount of energy required for a reaction to take place

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10
Q

What is the significance of enzymes?

Lower temperatures

A

Allows reactions to take place at a lower temperature than normal
This enables some metabollic processes to occur rapidly at 37*c

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11
Q

What happens if you change certain amino acids that are not a part of the active site

A

It prevents the enzyme from functioning as the changed amino acid could be the one that forms hydrogen bonds leading to a change in the tertiary structure

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12
Q

Describe how models of enzyme action have changed overtime

A

Initially lock and key model where it stated that the active site was a fixed shape and complementary to one substarte
Now it is induced fit model

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13
Q

Explain the specificity of enzymes (4)

A

● Specific tertiary structure determines shape of active site
○ Dependent on sequence of amino acids (primary structure)
● Active site is complementary to a specific substrate
● Only this substrate can bind to active site, inducing fit and forming an enzyme-substrate complex

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14
Q

What is a limitation of the lock and key model

A

The enzyme is ocnsidered to be a rigid structure and could only bind to one point
However enzymes can bind to sites other than the active iste
Strcutre is fexible

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