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Biology🧬 > Enzymes🧫 > Flashcards

Enzymes🧫 Flashcards

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1
Q

What is metabolism?

A

Chemical reactions taking place in your body

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2
Q

What are anabolic reactions?

A

Building up/synthesis

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3
Q

What are catabolic reactions?

A

Breaking down

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4
Q

What are enzymes?

A

Molecules controlling reactions in your body

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5
Q

What level of protein structure is shown by enzymes?

A

Tertiary structure - globular, specific 3D shape, hydrogen bonds, ionic bonds, disulphide bonds

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6
Q

Properties of enzymes

A
  • Specific - will only catalyse with a particular reaction
  • Not used up in the reactions - reusable
  • Combine with their substrates to form enzyme/substrate complexes - release products when finished
  • Only a small amount is used
  • Fast acting - high turnover number
  • Affected by changes in temp or pH
  • Many can only work if a cofactor is present
  • Can be slower or stopped by inhibitors
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7
Q

What are intracellular enzymes?

A

Functions within the cell where it was produced

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8
Q

What are extracellular enzymes?

A

Secreted by a cell and functions outside the cell

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9
Q

What is the lock and key theory?

A
  • Explains why enzymes are specific
  • Enzymes have an active site made up of 3-12 amino acids - has the right structure to fit with the substrate
  • The active site and substrate lock into place to form an enzyme/substrate complex
  • Products are formed at active site - have different shape so are repelled - active site is freed up
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10
Q

What is the induced fit theory?

A
  • Suggests active site may not exactly correspond to shape of the substrate
  • Active site is more flexible - module itself round the substrate
  • When it’s binds closely to the substrate the active site catalyses the reaction
  • Products are repelled
  • Enzyme reverts to relaxed shape
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11
Q

TIP

A

Always mention kinetic energy and more frequent successful collisions

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12
Q

What is activation energy?

A

The energy needed to start a chemical reaction

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13
Q

How does lowering the activation energy work?

A

Provides a different pathway for the reaction as the enzymes reduce the input of energy needed and allow reactions to take place at lower temperatures

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14
Q

What does lysozyme do?

A

Breaks chemical bonds in the outer wall of the bacteria - targets peptidoglycan

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15
Q

What is denaturing?

A
  • When factors alter the tertiary structure of the enzymes/3D shape by breaking hydrogen bonds - includes active site
  • Permanent change
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16
Q

What is inactivation?

A

Cooling the enzyme below the optimum temperature

17
Q

How does temperature affect the rate of activity of enzymes?

A
  • Increase give molecules more K.E which increases chance of successful collisions and impact - increases rate of reaction
  • Only increases to an optimum temp - begins to denature - hydrogen bonds break
18
Q

How does pH affect the rate of activity of enzymes?

A
  • Small changes in pH affect ROR - these are reversible - inactivation
  • Extreme changes in pH can denature an enzyme
  • Free H+ and OH- ions can affect the charges of amino acid side chains of the enzyme’s active site
  • Affects hydrogen bonds - alters tertiary
19
Q

How can a pH buffer help the rate of activity of enzymes?

A

It is a chemical that maintains a constant pH by absorbing excess ions

20
Q

How does enzyme concentration affect the rate of activity of enzymes?

A
  • ROR is directly proportional to the enzyme concentration

* Increasing enzyme concentration increases rate of reaction

21
Q

How does substrate concentration affect the rate of activity of enzymes?

A
  • Increasing the substrate concentration increases ROR up to a certain point - increases frequency of successful collisions
  • All the active sites become filled - working at maximum rate
22
Q

What is an inhibitor?

A
  • A substance that can slow down or stop a reaction
  • Combines with the enzyme and stops it from attaching to the substrate
  • Either reversible or non-reversible
23
Q

What is a competitive inhibitor?

A
  • Similar structure to substrate
  • Competes with substrate for active site of enzyme
  • Prevents formation of enzyme/substrate complexes - ROR decreases
  • Increasing substrate concentration can reduce the effects of a competitive inhibitor
24
Q

What is a non competitive inhibitor?

A
  • Doesn’t bind to active site - attaches to another part of the enzyme
  • Alters overall shape of the enzyme - including active site
  • Substrate can no longer bind to active site
  • Increasing substrate concentration doesn’t affect inhibition - not competing with substrate
25
Q

What are immobilised enzymes?

A

Enzymes that are bound to inert (unreactive) or trapped in a matrix

26
Q

Advantages of immobilised enzymes

A
  • More stable at higher temps and a wider range of pHs
  • Can be added or removed easily - helpful in controlling the reaction and avoids contamination, ensuring that a pure product is formed
  • Easily recovered and reused in industrial processes
  • A mixture of enzymes with different optimum pHs and temps can be used together
27
Q

Disadvantages of immobilising enzymes

A

Fixing process may damage enzymes

28
Q

Examples of immobilised enzymes

A

Biofuels, food production

29
Q

What are biosensors?

A

Device which uses enzymes to detect the presence of chemicals

30
Q

What is polymerisation?

A

Joining together of monomers

31
Q

When is the enzyme concentration the limiting factor?

A

At the start of the graph

32
Q

When is the substrate concentration the limiting factor?

A

Near the plateau when the reaction begins to slow down - most of the substrate has been converted into product - limits chance of a successful collision

33
Q

Why is the use of a control important in enzyme investigations?

A

It shows that it is the enzymes that are causing the effect that you are measuring (dependant variable)

34
Q

What is the usual control for an enzyme reaction?

A
  • Boil and cool the enzyme solution
  • This denatures the enzymes and ensures they will not catalyse any reactions
  • The experiment should then be repeated using the boiled and cooled solution - if the same results are obtained, indicates another factor is influencing the results

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