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Biology > Enzymes > Flashcards

Enzymes Flashcards

1
Q

What are enzymes?

A

Globular proteins that alter the rate of metabolic reactions and are known as biological catalysts

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2
Q

What type of proteins are enzymes?

A

Globular

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3
Q

What does anabolic mean?

A

Building up

Chemical reactions required for growth

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4
Q

What does catabolic mean?

A

Breaking down

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5
Q

What is metabolism?

A

The sun of all chemical reactions happening in the body

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6
Q

What factors may have an effect on enzyme activity?

A
  • Temperature
  • pH
  • Substrate concentration
  • Enzyme concentration
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7
Q

How do enzymes catalyse reactions?

A

They reduce activation energy

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8
Q

What is Vmax?

A

Maximum initial velocity

Enzymes can only increase RoR up to this point

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9
Q

What is the lock and key theory?

A
  • Active site = area within a tertiary structure of an enzyme that’s shape is complementary to the shape of a specific substrate
  • Only a specific substrate will “fit”
  • When the substrate is bound to the active site, an enzyme-substrate complex is formed
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10
Q

What is the induced-fit hypothesis?

A
  • More recently, evidence suggests the active site actually changes shape slightly as the substrate enters
  • The initial reaction between them is weak but they rapidly induce changes in the tertiary structure - strain on substrate
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11
Q

What are intracellular enzymes?

A

Enzymes that act within cells

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12
Q

What are extracellular enzymes?

A

Enzymes that act outside cells

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13
Q

Example of an enzyme that catalyses intracellular reactions?

A

Catalase

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14
Q

Example of an enzyme that catalyses extracellular reactions

A

Amylase and trypsin

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15
Q

How does temperature affect enzyme action?

A
  • Increase in temp
  • Increase in kinetic energy of particles
  • Particles move faster
  • Collide more frequently
  • Bonds holding protein together vibrate more
  • Vibrations increase until bonds strain and break
  • Changes shape as it denatures
  • Doesn’t form ESC
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16
Q

What is optimum temperature?

A

Where the enzyme has the highest rate of activity

Humans = 37°C

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17
Q

How does pH affect enzyme action?

A
  • A change in the pH refers to a change in hydrogen ion concentration
  • Hydrogen ions and ionic bonds between amino acid R-groups hold proteins in their precise 3D shape
  • When the pH changes from optimum, the structure of the enzyme (active site) is altered
  • However, if it returns back to optimum then it can return to it’s original shape - denaturalising
  • No/fewer ESC formed
18
Q

How does substrate concentration affect enzyme action?

A
  • Increased collision rate with active sites
  • More ESC
  • Until all active sites are occupied
19
Q

How does enzyme concentration affect enzyme action?

A
  • Will increase number of available active site in a particular area
  • More collisions
  • Leads to more ESC
  • If substrate runs out it will make no difference to rate
20
Q

What are coenzymes?

A

Organic molecules but are not necessarily a protein - vitamins

21
Q

What is Q10?

A

A measure of change in the rate of an enzyme controlled reaction if temperature is increased by 10°C
- The bigger the Q10 value, the bigger the difference in the rate

22
Q

What is a cofactor?

A

A non-protein chemical compound or metallic ion that is required for an enzyme’s activity as a catalyst

23
Q

What are inhibitors?

A

Molecules that prevent enzymes from carrying out their normal function

24
Q

What is competitive inhibition?

A
  • Competitive inhibitors gave a similar shape to the substrate
  • They can also bind to the active site
  • This stops the substrate forming an ESC
25
Q

What is non-competitive inhibition?

A
  • Non-competitive inhibitors bind to the allosteric site
  • Changes tertiary structure of enzyme and shape of active site
  • Active site no longer has complementary shape so substrate can’t bind
  • No more ESC are formed
26
Q

What is end-product inhibition?

A
  • A form of negative feedback

- When the product of a reaction act as an inhibitor to the enzyme from an earlier step in the sequence

27
Q

What are coenzymes?

A
  • Small (non a.a) organic compounds
  • Needed by some enzymes to work
  • They’re recycled, not used up
28
Q

How are coenzymes obtained?

A

From vitamins, e.g. vitamin B3

29
Q

What are cofactors?

A
  • Inorganic molecules
  • Attached to same enzyme, needed for the enzyme to function
  • Not used up
30
Q

How are inorganic cofactors obtained?

A

Via the diet as minerals, e.g. calcium

31
Q

What is a prosthetic group?

A
  • Same as cofactors excepts they are chemically bonded onto the enzyme
  • A non-protein group forming part of or combined with a protein
  • E.g. Zinc ions (Zn2+)
32
Q

What is precursor activation?

A
  • Many enzymes are produced in an inactive form (inactive precursor enzymes). These often need to undergo a change in shape, particularly the active site, to be activated
  • This can be achieved by the addition of a cofactor
33
Q

What is activation energy?

A

The minimum energy require for a reaction to complete

35
Q

What is Q10?

A
  • The temperature coefficient

- Measures the amount of change to a biological reaction caused by increasing the temperature by 10°C

36
Q

Describe reversible inhibitors

A
  • Can be reversed
  • Do not denature enzyme
  • Weakly bind to enzyme, e.g. H bonds
  • Could be temporary change/removal of: coenzyme or cofactors
37
Q

Describe irreversible inhibitors

A
  • Cannot be reversed
  • Enzyme is permanently denatured
  • Strongly bonded to enzyme, e.g. covalent bond
38
Q

Describe metabolic poisons as a type of enzyme inhibition

A
  • inhibit enzymes in essential metabolic pathways like respiration
  • E.g. cyanide
  • Normally non-reversible
39
Q

Give 2 types of enzyme inhibition

A

1- Metabolic poisons

2- Medicines

40
Q

Describe medicine as a type of enzyme inhibition

A
  • Inhibit enzymes in essential processes unique to pathogens
  • E.g. cell wall formation in bacteria (penicillin)
  • Protein synthesis in viruses (reverse transcriptase)
41
Q

Describe the role of product inhibition

A
  • When the product of an enzyme catalysed reaction bonds to an enzyme and inhibits its activity
  • Can be any type of inhibitor
  • E.g. competitive/non-competitive
  • They are always reversible
  • Help to regulate how much product is made
42
Q

How do you calculate Q10?

A

Rate of reaction X+10 / Rate of reaction X°C

Biology (19 decks)

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