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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
Describe lock and key theory
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
26
Describe induced fit model
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
27
Describe the process of induced fit model
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
28
How do low temperatures effect enzyme activity
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
29
How do high temperatures effect enzyme action which are still BELOW optimum
Higher temperatures have more kinetic energy More random collisions of active site and substrate per second More ESC Increased rate of reaction
30
What does Q10=3 mean
For every 10°c rise in temp - the rate of reaction trebled (x3 fast)
31
What is the optimum temp of enzymes in the human body
40°c
32
Describe what happens to enzymes when temperature increases
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
What type of ions are present in: Acids Alkalis
Acids-H+ ions | Alkalis-OH-
34
How do ions affect the active site
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
What happens in denaturation due to pH
Too many bonds break beyond the point of returning to original shape
36
What is renaturation
Where small changes in the pH away from optimum temperature are followed by a return in pH to its optimum
37
# 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 ```
R Hydrogen and ionic 3D shape Active site
38
What are extracellular enzymes
Enzymes that catalyse reactions outside of the cell
39
What enzyme hydrolyses proteins into amino acids in the stomach
Pepsin
40
What is a phagosome like
A vesicle They engulf and digest pathogens
41
What is the function of catalase
Breaks down hydrogen peroxide into water and oxygen
42
Define activation energy
The minimum energy needed to start a chemical reaction
43
How do enzymes lower activation energy
Forming enzyme-substrate complexes Which speeds up metabolic reactions
44
Describe lock and key theory
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
Describe induced fit model
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
Describe the process of induced fit model
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
How do low temperatures effect enzyme activity
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
How do high temperatures effect enzyme action which are still BELOW optimum
Higher temperatures have more kinetic energy More random collisions of active site and substrate per second More ESC Increased rate of reaction
49
What does Q10=3 mean
For every 10°c rise in temp - the rate of reaction trebled (x3 fast)
50
What is the optimum temp of enzymes in the human body
40°c
51
Describe what happens to enzymes when temperature increases above optimum
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
What type of ions are present in: Acids Alkalis
Acids-H+ ions | Alkalis-OH-
53
How do ions affect the active site
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
What happens in denaturation due to pH
Too many bonds break beyond the point of returning to original shape
55
What is renaturation
Where small changes in the pH away from optimum temperature are followed by a return in pH to its optimum
56
# 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 ```
R Hydrogen and ionic 3D shape Active site
57
When will the reaction be the quickest
When the enzyme and substrate are mixed together
58
Describe the effect of increasing substrate concentration
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
Define in inhibitor
A substance that slows down the rate of an enzyme catalysed reaction by affecting the enzyme in some way
60
Describe competitive inhibitors
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
Describe a non-competitive inhibitor
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
Give an example of a competitive inhibitor
Statins which is used to synthesise cholesterol
63
How does penicillin work as an inhibitor in medicine
It penicillin helps form the cell walls of bacteria The cell wall protein not constructed so results in bursting of the bacteria
64
How does ethanol work as a competitive inhibitor (in antifreeze)/
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
Give two examples of non competitive inhibitors
Organophosphates> found in insecticides Inhibits enzyme used in nerve impulse conduction Proton pumps are used to treat long term indigestion
66
What are cofactors
A non-protein helper that must be present for the enzyme reaction to take place at the appropriate rate
67
Describe coenzymes
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
Describe inorganic ions which are used as cofactors
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
Maltase and amylase both require what ion
Chloride ions
70
describe prosthetic groups
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
What is a inactive precursor enzyme
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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