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biology year 1 > 3.1.4.2 Proteins - Enzyme Action > Flashcards

3.1.4.2 Proteins - Enzyme Action Flashcards

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1
Q

How did scientists discover the induced fit model of enzyme action?

A

They noticed that other molecules could bind to enzymes, which then affected the enzyme’s activity. This led to the conclusion that the enzyme shape must be changing.

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2
Q

What is a substrate?

A

The substance on which an enzyme acts

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3
Q

Why are enzymes essential to organisms?

A

They allow essential chemical reactions to occur rapidly at low temperatures e.g. 37 °C.

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4
Q

Enzymes that catalyse chemical reactions outside of cells are called…

A

extracellular enzymes

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5
Q

The functional part of an enzyme is called the…

A

active site

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6
Q

Describe the lock and key model of enzyme action

A
  • A substrate is specific to an enzyme.
  • A substrate binds to the active site of an enzyme.
  • This lowers the activation energy.
  • Product is released from enzyme.
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7
Q

Which 3 conditions must be satisfied for a chemical reaction to take place?

A
  • The substrates must collide with sufficient energy to alter the arrangement of their atoms
  • The energy of the products must be lower than the substrates.
  • The activation energy needs must be met.
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8
Q

Which have a higher energy level: substrates or products?

A

products

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9
Q

The specific 3D shaped active site of an enzyme is determined by..

A

its sequence of amino acids (primary structure)

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10
Q

Enzymes that catalyse reactions inside of cells are called…

A

intracellular enzymes

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11
Q

When a substrate binds to the active site we call the resulting structure an…

A

enzyme-substrate complex

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12
Q

A substrate does not have the same shape as the active site it has a _____________ shape.

A

complementary

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13
Q

What does the following describe:

  • A substrate is specific to an enzyme.
  • A substrate binds to the active site of an enzyme.
  • This lowers the activation energy.
  • Product is released from enzyme.
A

The lock and key model of enzyme action

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14
Q

Hormones are proteins that have a binding site so that they can switch on or off bodily processes. Are they enzymes?

A

No - many proteins have binding sites or receptor sites. These are not active sites.

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15
Q

Which type of biological molecule are enzymes?

A

Proteins

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16
Q

Which structural type of protein are enzymes?

A

Globular proteins

17
Q

What do we call the initial energy required for a chemical reaction to take place?

A

Activation energy

18
Q

Define an enzyme

A

Enzymes are biological catalysts that speed up chemical reactions without being used up or changed.

19
Q

How does a substrate temporarily bind to an enzyme active site?

A

The substrate temporarily forms bonds with certain amino acids in the active site.

20
Q

What does the following describe:

  • Substrate approaches active site
  • Enzyme changes shape and forms functional active site.
  • Enzyme moulds to substrate
  • Change in shape puts a strain on bonds of substrate, lowering activation energy.
  • Product is released from enzyme.
A

The induced fit model of enzyme action

21
Q

What is the name of the currently accepted model of enzyme action?

A

The induced fit model of enzyme action

22
Q

Describe the lock and key model of enzyme action.

A
  • A substrate is specific to an enzyme.
  • A substrate binds to the active site of an enzyme.
  • This lowers the activation energy.
  • Product is released from enzyme.
23
Q

Why are enzymes still effective even in small amounts?

A

Because they are not used up or changed so can be used again and again.

24
Q

Describe the induced fit model of enzyme action

A
  • Substrate approaches active site
  • active site not complementary/will fit substrate
  • active site changes shape and forms functional active site - as substrate binds
  • Enzyme moulds to substrate
  • Change in shape puts a strain on bonds of substrate, lowering activation energy.
25
Q

Why does formation of enzyme substrate complex increase rate of reaction?

A

Reduces activation energy

due to the bending/weakening of bonds

26
Q

explain the difference in rates of reaction at 60 degrees Celsius and 37 degrees Celsius between 20 and 40 minutes?

A
  • 60 degrees causes denaturation of ALL enzymes
  • reaction stops sooner because active site shape changed
  • substrate available when denatured
  • but not converted to product
27
Q

scientists have investigated the effects of competitive and non-competitive inhibitors of the enzyme maltase.

describe competitive and non-competitive inhibition of an enzyme?

A

COMPETITIVE

  • inhibitor similar shape to substrate
  • binds in to active site of enzyme
  • inhibition can be overcome by more substrate

NON - COMP

  • inhibitor binds to site on enzyme other than active site
  • changes shape of active site
  • cannot be overcome by adding more substrate
28
Q

a scientist investigated an enzyme that catalyses the following reaction

ATP –> ADP + Pi

the scientists set up 2 experiments C and L

experiment C used:

  • the enzyme
  • different concentrations of ATP

experiment L used:

  • the enzyme
  • different concentrations of ATP
  • a sugar called lyxose

lyxose binds to the enzyme

suggest a reason for the increased rate of reaction for when lyxose was used?

A
  • binding alters the tertiary structure of enzyme
  • causes active site to change shape
  • more E-S complexes formed
29
Q

comment on differences in specificity of 2 enzymes?

A
  • not very specific, acts on number of diff proteins
  • highly specific, acts on single protein
30
Q

how would you calculate optimum temperature more precisely?

A

carry out same experiment

  • using NARROWER TEMP intervales
31
Q

explain why the induced fit model is a better explanation of enzyme action than the lock and key model?

A
  • matches current observations more clearly
  • e.g. enzyme activity being changed when molecules bind at sites other than active site
  • enzyme mol changes shape when other mol bind to them
32
Q

enzyme Y is found in the stomach of young mammals where it acts on a single soluble protein found in milk, causing it to coagulate(clot).

suggest a possible purpose of enzyme Y in the mammalian stomach?

A
  • milk only food in diet of young mammals
  • enzyme clots milk SO stays in stomach for longer
  • so enzyme has more time to act on it
  • so broken down into prod = absorbed
  • if remained liquid, would have passed through and only PARTIALLY digested
33
Q

suggest why enzymes are attached to the inner membrane of an organelle in a very precise sequence?

A
  • greater chance of each enzyme coming into contact with its substrate
  • more efficient
34
Q

suggest one advantage of end-produce inhibition being non-competitive rather than competitive.

relate your answer to how the 2 types of inhibition take place?

A
  • in non comp - binds to somewhere else on enzyme (not active site)
  • so increase in substrate doesnt affect the rate of E-SC produced
  • as enzymes active site shape changed
  • level of end-product doesn’t fluctuate with level of substrate
  • in comp - inhibitor = similar shape to substrate
  • binds to enzymes active site
  • level of end - product fluctuates with level of substrate
35
Q

mothers were not told which solution contained lactase.

suggest why?

A

avoid bias by mother

36
Q

doctors investigated babies who were bottle-fed with baby milk formula and suffered from colic.

colic is a condition that affects the gut and makes babies cry.

suggest one variable the doctors would have to control in this study to make it a fair test.

explain your answer?

A
  • volume of milk
  • so same dosage of lactose
37
Q

scientists have investigated the effects of competitive and non-competitive inhibitors of enzyme maltase.

describe comp and non-comp inhibtion of an enzyme

A
  • inhibitors prevent formation of ES-C

COMP

  • inhibitor similar shape to substrate
  • binds in to active site of enzyme
  • can be overcome by more substrate

NON-COMP

  • inhibitor binds to site on enzyme other than active site
  • prevents formation of active site
  • cannot be overcome by addition of substrate
38
Q
A

biology year 1 (45 decks)

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