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Biology > 2.5 enzymes > Flashcards

2.5 enzymes Flashcards

1
Q

enzyme

A

a globular protein which acts as a biological catalyst by speeding up the rate of a chemical reaction

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2
Q

why are enzymes able to be reused?

A

Enzymes are not changed or consumed by the reactions they catalyse

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3
Q

substrate

A

the molecules the enzyme reacts with

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4
Q

active site

A

the region on the surface of the enzyme which binds to the substrate molecule

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5
Q

where do enzyme reactions typically occur?

A

in aqueous solutions

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6
Q

catalase

A

an enzyme found in the blood, and in most living cells, that catalyses the decomposition of hydrogen peroxide into water and oxygen.

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7
Q

denaturation

A

a structural change in a protein that alters its three-dimensional shape and causes the loss of its biological properties.

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8
Q

enzyme activity

A

a measure of the ability of an enzyme to catalyse a specific reaction.

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9
Q

hydrolysis

A

decomposition of a chemical compound by reaction with water.

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10
Q

lactase

A

the enzyme responsible for catalysing the split of lactose into galactose and glucose.

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11
Q

lactose

A

a disaccharide (C12H22O11) found in milk that may be hydrolysed to yield glucose and galactose.

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12
Q

membrane-bound

A

when an enzyme is fixed in its position

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13
Q

describe enzyme catalysis

A
  1. first requires that the substrate has close physical proximity with the active site
  2. When a substrate binds to the enzyme’s active site, an enzyme-substrate complex is formed
  3. the enzyme catalyses the conversion of the substrate into product, creating an enzyme-product complex
  4. The enzyme and product then dissociate – as the enzyme was not consumed, it can continue to catalyse further reactions
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14
Q

what does increasing the rate of enzyme catalysis accomplish?

A

improves the frequency of collisions b/w substrate and enzyme

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15
Q

2 ways to increase rate of enzyme catalysis

A
  1. Increasing the molecular motion of the particles (thermal energy)
  2. Increasing the concentration of particles (either substrate or enzyme concentrations)
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16
Q

how does denaturation affect the enzyme?

A

negatively affect the enzyme’s capacity to bind the substrate

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17
Q

what factors influence the rate of activity of an enzyme

A

Temperature, pH and substrate concentration

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18
Q

describe process of denaturation

A
  1. the shape and chemical properties of the active site are highly dependent on the tertiary structure of the enzyme
  2. the chemical bonds which are necessary to maintain the tertiary structure of the enzyme are disrupted
  3. enzyme cannot bind to substrate
19
Q

draw graph of The Effect of Temperature on Enzyme Activity

A

see ipad

20
Q

how does temperature affect enzyme activity?

A
  • Low temperatures result in insufficient thermal energy for the activation of an enzyme-catalysed reaction to proceed
  • Increasing the temperature will increase the speed and motion of both enzyme and substrate, resulting in higher enzyme activity
21
Q

how does pH affect enzyme activity?

A
  • Changing the pH will alter the charge of the enzyme, which in turn will alter protein solubility and overall shape
  • Changing the shape or charge of the active site will diminish its ability to bind the substrate, abrogating enzyme function
  • Enzymes have an optimal pH (may differ between enzymes) and moving outside this range diminishes enzyme activity
22
Q

how does substrate concentration affect enzyme activity?

A
  • Increasing substrate concentration will increase the activity of a corresponding enzyme
  • More substrates mean there is an increased chance of enzyme and substrate colliding and reacting within a given period
  • After a certain point, the rate of activity will cease to rise regardless of any further increases in substrate levels
  • This is because the environment is saturated with substrate and all enzymes are bound and reacting (Vmax)
23
Q

immobilized enzymes

A
  • have been fixed to a static surface in order to improve the efficiency of the catalysed reaction
  • widely used in industry
24
Q

in general, why are immobilized enzymes helpful?

A
  • Enzyme concentrations are conserved as the enzyme is not dissolved – hence it can be retained for reuse
  • Separation of the product is more easily achieved as the enzyme remains attached to the static surface
25
Q

Common Industrial Uses of Enzymes

A

biocatalysis, food and beverage, animal feed, pharmaceuticals, biofuels, household items

26
Q

draw the Breakdown of Lactose by the Enzyme Lactase

A

see ipad

27
Q

how is lactose-free milk produced?

A

Lactose-free milk can be produced by treating the milk with the enzyme lactase

The enzyme lactase can be bound to alginate beads and immobilized. The beads are then packed in a container and milk is allowed to flow through it. Lactose is converted to glucose and galactose as it flows through the container with the immobilized enzymes. The solution leaving the container contains the products which are collected

28
Q

Advantages of Lactose-Free Dairy Products

A

source of dairy for lactose-intolerant individuals

increases sweetness bc monosaccharides are sweeter tasting

reduces the crystallisation of ice-creams as monosaccharides are more soluble and thus less likely to crystalise

reduce production time for cheeses and yogurts (bacteria ferment monosaccharides more readily)

29
Q

relationship b/w acidic substances (less than 7) and hydrogen?

A

donates hydrogen ions (i.e. high H+ concentration)

30
Q

relationship b/w basic substances (more than 7) and hydrogen?

A

accept hydrogen ions (i.e. high OH– concentration)

31
Q

2 models that describe enzyme-substrate reaction

A

The ‘lock and key’ model
The ‘induced fit’ model

32
Q

lock and key model

A

According to the lock and key model, the enzyme’s active site complements the substrate precisely

The substrate fits a particular active site like a key fits into a particular lock

This theory of enzyme-substrate interaction explains how enzymes exhibit specificity for a particular substrate

33
Q

induced fit model

A

According to the induced fit model, the enzyme’s active site is not a completely rigid fit for the substrate

Instead, the active site will undergo a conformational change when exposed to a substrate to improve binding

This theory of enzyme-substrate interactions has two advantages compared to the lock and key model:

It explains how enzymes may exhibit broad specificity (e.g. lipase can bind to a variety of lipids)
It explains how catalysis may occur (the conformational change stresses bonds in the substrate, increasing reactivity)

34
Q

6 types of enzymes

A

hydrolase, isomerase, lyase, oxidoreductase, synthetases, transferase

35
Q

reaction & examples of hydrolase enzymes

A

hydrolysis
- lipase, protease

36
Q

reaction & examples of isomerase enzymes

A

rearrangement of atoms w/in a molecule
- phosphohexoisomerase

37
Q

reaction & examples of lyase enzymes

A

splitting chemicals into smaller parts w/o using water
- decarboxylases, aldolases

38
Q

reaction & examples of oxidoreductase enzymes

A

transfer electrons or hydrogen atoms from one molecule to another
- dehydrogenases, oxidases

39
Q

reaction & examples of synthetase enzymes

A

joining of 2 molecules by the formation of new bonds
- DNA ligase, DNA polymerase

40
Q

reaction & examples of transferase enzymes

A

moving a functional group from one molecule to another
- kinases, transaminases

41
Q

draw graph of The Effect of pH on Enzyme Activity

A

see ipad

42
Q

draw graph of The Effect of substrate concentration on Enzyme Activity

A

see ipad

43
Q

advantages of enzyme-substrate specificity

A
  • the specificity helps to control where a reaction takes place
  • the specificity helps to control when reactions takes place
  • the specificity helps to control which reactions should take place & prevents unnecessary reactions from taking place
44
Q

activation energy

A

the minimum energy required for a reaction to occur. Enzymes lower the activation energy of a reaction.

Biology (37 decks)

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