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BIOLOGY AS OCR > Chapter 2.4 ENZYMES > Flashcards

Chapter 2.4 ENZYMES Flashcards

1
Q

Why are enzymes thought of as catalysts ? (3)

A
  • remain unchanged at the end of reaction
  • small amount can catalyse the conversion of a large number of substrate molecules
  • reduces activation energy
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2
Q

How to you alter the shape of the active site ?

2

A
  • change in Ph

- change in temperature

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3
Q

What kind of enzymes are there ?

2

A
  • Catabolic - big broken to small

- Anabolic -small made to big

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4
Q

Outline the structure of catalase ?

  • chains
  • prosthetic group
A
  • 4polypeptide chains

- Haem group with iron

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5
Q

Where is catalase found ?

A
  • lysosomes Called peroxisomes
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6
Q

What could changes in the DNA sequence do to the enzyme ?
Start from mRNA
( 5)

A 
1-changes in protein coded hence change in MRNA 
2-change of primary structure
3-tertiary structure changes shape 
4-active site changes shape 
5-enzyme can’t catalyse reaction
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7
Q

What is a cofactor ?

A

A substance that has to be present to ensure enzyme catalysed reaction takes place at an appropriate rate .

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8
Q

What’s a prosthetic group?

3

A
  • permanent attached cofactor
  • covalently bonded
  • examples : Haem group ( Fe2+)
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9
Q

Other cofactor examples ?

3

A
  • mineral ions
    -organic coenzymes example : B12 , folic acid etc
    = temporary associations with enzyme
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10
Q

What are the two scenarios of cofactors ?

4

A

1-co substrates to make correct shape to bind to active site
2- charge distribution on surface of enzymes active site changes

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11
Q

What bonds are present in prosthetic groups ?

1

A

Covalent

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12
Q

What bonds are present in Metallic ions?

1

A

Ionic bonds

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13
Q

What bonds are present in coenzyme /enzyme substrate molecule ?
(2)

A

Ionic /hydrogen bonds

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14
Q

What does the lock and key model say ?
(5)
-complexes
-collision

A
  • if a substrate = successful collision with enzyme = ESC
  • EPC
  • product molecules leave site
  • enzyme makes another ES complex
  • shapes of substrate and enzyme = complementary !
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15
Q

What does the induced fit hypothesis say?

2

A
  • active site = complementary shape to substrate molecule but R groups change a little so active sites are more precise
  • fits like glove
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16
Q

How do enzymes lower activation energy ?

1

A
  • bring molecules close together to react
17
Q

What happens when you increase temp to enzymes ?

3

A
  • ke causes particles to move faster
  • rate if collision increases
  • force of collisions increases
18
Q

What does over heating the enzyme do ?

5

A
  • molecules vibrate
  • hydrogen bonds break
  • tertiary structure unfolds
  • substrate no longer fills active site
  • enzyme is denatured
19
Q

What’s the effect of altering PH ?

4

A
  • H+ ions attracted to negative parts
  • excess H+ ions interfere with hydrogen bonds and ionic forces
  • active site hanged shape
  • enzyme denatures
20
Q

What happens if you increase substrate concentration?

2

A
  • rate increases up to a point then plateaux as all active sites are filled ! What
21
Q

What’s Q10?
(2)
Equation ?

A
  • temperature coefficient

- rate of reaction at T+10 / rate of reaction at T

22
Q

What’s enzyme synthesis ?

1

A
  • particular enzymes switched on/ off
23
Q

Why do cells go through enzyme degradation ?

2

A
  • elimination of abnormal shaped proteins

- regulation of metabolism ( eliminate surplus enzymes )

24
Q

What’s competitive inhibition.

3

A
  • when inhibitor has similar shape to substrate
  • blocks active site ( no binding required )
  • substrate can’t bond
25
Q

What’s non competitive inhibition ?

2

A
  • bonds to allosteric site

- active site shape changes

26
Q

What kind of bond makes a irreversible inhibitor ?

1

A

Strong covalent bonds

27
Q

What kinds of bond make reversible inhibitors ?

3

A
  • weak hydrogen bonds
  • weak ionic bonds
  • inhibitor can be removed !
28
Q

How are enzymes in organisms which live in hot conditions different ?
(1)

A
  • more disulfide bridges ( heat stable )
29
Q

What’s a buffer solution ?

1

A

Resists ph changes by accepting or donating protons .

30
Q

What does cyanide do ?

3

A

CN- ions bind irreversibly to enzyme found in mitochondria - inhibit final stage of respiration

  • paralyses
  • Inhibits AChE ( found in neuromuscular synapses )
31
Q

Name some examples of enzyme inhibition drugs and poisons ?

Name 3

A
  • snake venom
  • Cyanide
  • Aspirin
  • ATPase
  • ACE inbitor
  • antiretroviral drugs

BIOLOGY AS OCR (12 decks)

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