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A Level: Biology > Enzymes > Flashcards

Enzymes Flashcards

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1
Q

What happens in a dipeptide formation

A

A condensation reaction
H20 is made
A peptide bond is formed
Molecule made is called a dipeptide

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2
Q

Describe hydrolysis

A

H20 is used
Peptide bond is broken
Amino acids are formed from the dipeptide

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3
Q

Define primary structure

A

The specific sequence of amino acids in a polypeptide chain

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4
Q

Define secondary structure

A

The cooling and pleating of parts of the polypeptide chain to form an alpha helix or a beta pleated sheet

Held together by hydrogen bonds

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5
Q

Define tertiary structure

A

When the secondary alpha helix and beta pleats fold to five a complex 3D specific shape

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6
Q

Describe the bonds that hold the tertiary structure in place

A

Hydrogen bonds between polar groups

Disulphides bonds are covalent bonds formed between sulphurs in the r group of the amino acid cytesine

Ionic bonds between r groups of amino acids

Hydrophobic interactions between non polar r groups

Hydrophilic r groups on the outside of molecule in contact with water

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7
Q

What is the job of a catalyst

A

To speed up the rate of reaction

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8
Q

What type of molecule is an enzyme

A

A protein

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9
Q

What enzyme does protein synthesis use

A

Peptidyl transferase

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10
Q

Name a product which enzymes are used in

A

Biological washing powders

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11
Q

Give an advantage of a biological washing powder

A

Can sometimes work at low temperatures which can save energy and the environment

Some only work well at 40°

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12
Q

What type of protein are enzymes

A

Globular

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13
Q

Describe globular proteins

A

Have a specific 3D shape
Soluble in water
Have an active site
Ball like structure

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14
Q

Name the enzyme used in photosynthesis

A

Rubisco

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15
Q

Name the substrate that

Amylase creates from starch
Maltase creates from maltose

A

Maltose

Alpha glucose

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16
Q

Give another name for :

A hydrolysis reaction
A condensation reaction

A

Catabolic

Anabolic

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17
Q

Where do reactions occur in:

Extracellular enzymes
Intercellular proteins

A

Outside a cell

Inside a cell

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18
Q

Name the product and the bond broken for:

Proteins
Fats
Polysaccharides

A

Amino acids - peptide bond
Glycerol and fatty acids- Ester bonds
Disaccharides- glycosidic

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19
Q

What are extracellular enzymes

A

Enzymes that catalyse reactions outside of the cell

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20
Q

What enzyme hydrolyses proteins into amino acids in the stomach

A

Pepsin

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21
Q

What is a phagosome like

A

A vesicle

They engulf and digest pathogens

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22
Q

What is the function of catalase

A

Breaks down hydrogen peroxide into water and oxygen

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23
Q

Define activation energy

A

The minimum energy needed to start a chemical reaction

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24
Q

How do enzymes lower activation energy

A

Forming enzyme-substrate complexes

Which speeds up metabolic reactions

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25
Q

Describe lock and key theory

A

The shape of the active site of the enzyme is always complimentary to the shape of the substrate

Like a lock it is complimentary to its key

Shape of active site does not change

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26
Q

Describe induced fit model

A

The model is based on more evidence and suggests the active site of the enzyme is not fully complimentary to the substrate

But as the substrate collided with the active site the enzyme active site changes shape

Causing the active site to fit more closely with the substrate

Puts strain on bonds in the substrate meaning they break more easily

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27
Q

Describe the process of induced fit model

A

The active site is not fully complimentary shape to the shape of substrate. But the active site has charged amino acids r groups which are attracted to the substrate.

Substrate collides randomly with active site

Enzyme changed shape and active site becomes fully complimentary

This puts strain on the bonds meaning they break more easily

Produces enzyme product complexes

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28
Q

How do low temperatures effect enzyme activity

A

Low temps have less kinetic energy

Decreasing random collisions of substrate and active site

Less ESC firmed per second

Slower rate of reaction

Enzyme is not denatured

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29
Q

How do high temperatures effect enzyme action which are still BELOW optimum

A

Higher temperatures have more kinetic energy

More random collisions of active site and substrate per second

More ESC

Increased rate of reaction

30
Q

What does Q10=3 mean

A

For every 10°c rise in temp - the rate of reaction trebled (x3 fast)

31
Q

What is the optimum temp of enzymes in the human body

A

40°c

32
Q

Describe what happens to enzymes when temperature increases

A

The enzyme molecules have increased KE

The enzyme molecule vibrates more

Too much KE causes the hydrogen and ionic bonds to break

The 3D shape changes

Active site is altered

No longer complimentary

Less ESC

33
Q

What type of ions are present in:

Acids
Alkalis

A

Acids-H+ ions

Alkalis-OH-

34
Q

How do ions affect the active site

A

Charged ions attract or repel from charges in the protein structure

Changes the charge of active site

Bonds break

3D structure changes (inc active site)

Fewer ESC

35
Q

What happens in denaturation due to pH

A

Too many bonds break beyond the point of returning to original shape

36
Q

What is renaturation

A

Where small changes in the pH away from optimum temperature are followed by a return in pH to its optimum

37
Q

Fill in the blanks:

\_\_ group interactions are disrupted
\_\_\_\_\_\_ and \_\_\_\_\_\_ bonds break
The tertiary structure and \_\_\_\_ \_\_\_\_\_\_\_\_\_ of enzyme changes
Change shape of \_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_
Prevents substrate from bonding
A

R
Hydrogen and ionic
3D shape
Active site

38
Q

What are extracellular enzymes

A

Enzymes that catalyse reactions outside of the cell

39
Q

What enzyme hydrolyses proteins into amino acids in the stomach

A

Pepsin

40
Q

What is a phagosome like

A

A vesicle

They engulf and digest pathogens

41
Q

What is the function of catalase

A

Breaks down hydrogen peroxide into water and oxygen

42
Q

Define activation energy

A

The minimum energy needed to start a chemical reaction

43
Q

How do enzymes lower activation energy

A

Forming enzyme-substrate complexes

Which speeds up metabolic reactions

44
Q

Describe lock and key theory

A

The shape of the active site of the enzyme is always complimentary to the shape of the substrate

Like a lock it is complimentary to its key

Shape of active site does not change

45
Q

Describe induced fit model

A

The model is based on more evidence and suggests the active site of the enzyme is not fully complimentary to the substrate

But as the substrate collided with the active site the enzyme active site changes shape

Causing the active site to fit more closely with the substrate

Puts strain on bonds in the substrate meaning they break more easily

46
Q

Describe the process of induced fit model

A

The active site is not fully complimentary shape to the shape of substrate. But the active site has charged amino acids r groups which are attracted to the substrate.

Substrate collides randomly with active site

Enzyme changed shape and active site becomes fully complimentary

This puts strain on the bonds meaning they break more easily

Produces enzyme product complexes

47
Q

How do low temperatures effect enzyme activity

A

Low temps have less kinetic energy

Decreasing random collisions of substrate and active site

Less ESC firmed per second

Slower rate of reaction

Enzyme is not denatured

48
Q

How do high temperatures effect enzyme action which are still BELOW optimum

A

Higher temperatures have more kinetic energy

More random collisions of active site and substrate per second

More ESC

Increased rate of reaction

49
Q

What does Q10=3 mean

A

For every 10°c rise in temp - the rate of reaction trebled (x3 fast)

50
Q

What is the optimum temp of enzymes in the human body

A

40°c

51
Q

Describe what happens to enzymes when temperature increases above optimum

A

The enzyme molecules have increased KE

The enzyme molecule vibrates more

Too much KE causes the hydrogen and ionic bonds to break

The 3D shape changes

Active site is altered

No longer complimentary

Less ESC

52
Q

What type of ions are present in:

Acids
Alkalis

A

Acids-H+ ions

Alkalis-OH-

53
Q

How do ions affect the active site

A

Charged ions attract or repel from charges in the protein structure

Changes the charge of active site

Bonds break

3D structure changes (inc active site)

Fewer ESC

54
Q

What happens in denaturation due to pH

A

Too many bonds break beyond the point of returning to original shape

55
Q

What is renaturation

A

Where small changes in the pH away from optimum temperature are followed by a return in pH to its optimum

56
Q

Fill in the blanks:

\_\_ group interactions are disrupted
\_\_\_\_\_\_ and \_\_\_\_\_\_ bonds break
The tertiary structure and \_\_\_\_ \_\_\_\_\_\_\_\_\_ of enzyme changes
Change shape of \_\_\_\_\_\_\_ \_\_\_\_\_\_\_\_
Prevents substrate from bonding
A

R
Hydrogen and ionic
3D shape
Active site

57
Q

When will the reaction be the quickest

A

When the enzyme and substrate are mixed together

58
Q

Describe the effect of increasing substrate concentration

A

More enzyme substrate complex is the forms therefore the reaction increases

Eventually all active sites will be occupied and therefore the reaction will reach v max

Enzyme concentration is the limiting factor

59
Q

Define in inhibitor

A

A substance that slows down the rate of an enzyme catalysed reaction by affecting the enzyme in some way

60
Q

Describe competitive inhibitors

A

Have a similar shape to the substrate that are complimentary to the active site they fit into the active site forming an enzyme inhibitor complex which blocks the substrate from binding

this means there are fewer active sites available and fewer enzyme substrate complex is which reduces the rate of reaction

61
Q

Describe a non-competitive inhibitor

A

Binds away from an active site at an allosteric site which is a different shape to the active site

Causing changes to the Tertiary structure in 3-D shape of the enzyme

the active site shape alters which are no longer complimentary to the substrate this can sometimes be permanent and reduces the rate of reaction

62
Q

Give an example of a competitive inhibitor

A

Statins

which is used to synthesise cholesterol

63
Q

How does penicillin work as an inhibitor in medicine

A

It penicillin helps form the cell walls of bacteria

The cell wall protein not constructed so results in bursting of the bacteria

64
Q

How does ethanol work as a competitive inhibitor (in antifreeze)/

A

Higher the ethanol conc the greater chance of ethanol binding with active site

Less chance of ethylene glycol binding to active site and is broken down

Less production of oxalis acid (toxic)

65
Q

Give two examples of non competitive inhibitors

A

Organophosphates> found in insecticides
Inhibits enzyme used in nerve impulse conduction

Proton pumps are used to treat long term indigestion

66
Q

What are cofactors

A

A non-protein helper that must be present for the enzyme reaction to take place at the appropriate rate

67
Q

Describe coenzymes

A

Often made from vitamins
they are small organic non-protein molecules that bind loosely with the active site
they are charged and are recycled so can be used again

68
Q

Describe inorganic ions which are used as cofactors

A

Charged particles which can affect the charge distribution and sometimes the shape of the active site
the ions bind to the enzyme making enzyme substrate complexes form more easily

69
Q

Maltase and amylase both require what ion

A

Chloride ions

70
Q

describe prosthetic groups

A

Permanent parts of an enzyme molecule that helps with the 3-D shape

They are sometimes required by certain enzymes in order to function

71
Q

What is a inactive precursor enzyme

A

Enzymes which are produced in an inactive form

They often need to undergo a change in shape - once this happens the enzyme becomes activated (could be achieved by adding a cofactors or another enzyme/ or through a change in conditions such as pH or temp)

A Level: Biology (18 decks)

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