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Biology > Proteins and Enzymes > Flashcards

Proteins and Enzymes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Monomers of proteins are

A

amino acids

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2
Q

When is a dipeptide formed

A

When two amino acids join together

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3
Q

When is a polypeptide formed

A

When more thean two amino acids join together

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4
Q

Proteins are made up of more than

A

One polypeptide

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5
Q

What is the structure of amino acids

A

a carboxyl group, an amine or amino group and an R group attached to a carbon atom

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6
Q

R groups generally contain

A

Carbon, except glycine which has just one hydrogen atom

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7
Q

All living things only share a bank of

A

20 amino acids

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8
Q

Amino acids are linked together by

A

Condensation reactions

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9
Q

What is the primary sequence

A

The sequence of amino acids in the polypeptide chain

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10
Q

What are the four levels of proteins

A

Primary, Secondary, Tertiary, Quaternary

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11
Q

During the secondary structure what bonds form between the amino acids

A

Hydrogen Bonds

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12
Q

What are the two structures in the secondary structure of proteins

A

Alpha Helix or Beta pleated sheets

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13
Q

What bonds form in the tertiary structure

A

Hydrogen disulfide bridges and ionic bonds

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14
Q

When do disulfide bridges form

A

Whenever two molecules of the amino acid cysteine bonds to the sulfur atom in one cysteine bonds from a single polypeptide chain

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15
Q

How are alpha helix’s formed

A

By hydrogen bonds forming in between the amino acids causing the polypeptide chain to coil into an alpha helix

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16
Q

How are Beta pleated sheets formed

A

Hydrogen bonds form between the amino acids in the chain causing it to automatically fold

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17
Q

During the tertiary structure what happens to the coiled or folded chain of amino acids

A

They coil or fold further

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18
Q

When do disulphide bridges form

A

Whenever two molecules of the amino acid cysteine come close together- the sulfur atom in on cysteine bonds to the sulfur atom in the other

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19
Q

For proteins made from a single polypeptide chain , the tertiary structure forms their final

A

3D structure

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20
Q

What is the quaternary structure

A

The way multiple polypeptide chains are assembled together

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21
Q

For proteins made from more then one polypeptide chain the quaternary structure is the protein’s final

A

3D structure

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22
Q

A protein’s shape determines it’s

A

Function

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23
Q

Why are enzymes roughly spherical in shape

A

Due to tight folding of the polypeptide chain

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24
Q

Name 3 quaternary level proteins

A

Haemoglobin, collagen, insulin

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25
Q

Haemoglobin is compact and an insoluble protein which makes it easy to

A

Transport, and carry oxygen around the body

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26
Q

Enzymes often have a role in

A

Metabolism

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27
Q
A
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28
Q

Do enzymes break down or synthesise large molecules

A

Both

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29
Q

Are enzymes soluble or insoluble

A

soluble

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30
Q

Antibodies are involved in the

A

Immune response

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30
Q

Where are antibodies found

A

In the blood

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31
Q

What are antibodies made up of

A

2 light (short) polypeptide chains and two heavy (long) polypeptide chains bonded together

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32
Q

Antibodies have variable regions which means that the

A

Amino acid sequences in these regions vary greatly

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33
Q

Channel proteins contain hydrophobic and hydrophilic amino acids causing the protein to

A

Fold up and form a channel

34
Q

Structural proteins consist of

A

long polypeptide chains lying parallel to each other with cross links between them.

35
Q

Collagen is a great supportive tissue in animals because

A

It has three polypeptide chains tightly coiled together, which makes it strong

36
Q

Food test to identify protein

A

Biuret Test

37
Q

For the protein test to take place the test solution must be

A

Alkaline, so first add a few drops of sodium hydroxide solution

38
Q

What is added to test solution to test for protein

A

Coper sulfate solution

39
Q

If a protein is present the solution turns from

A

Blue to purple

40
Q

Enzymes are

A

Biological catalysts

41
Q

Enzymes catalyse metabolic reactions at both

A

Cellular level (respiration), and for the organism as a whole (digestion)

42
Q

Enzyme action can occur

A

Intracellular or Extracellular

43
Q

What is an active site

A

The part of the enzyme where substrate molecules bind to, it has a specific shape

44
Q

Enzymes are highly specific due to

A

Their tertiary structure

45
Q

What is activation energy

A

The certain amount of energy needed to be supplied to the chemicals before the reaction will start, often provided as heat energy

46
Q

Enzymes lower the

A

Amount of activation energy that’s needed often making reactions occur at lower temperature

47
Q

What is the enzyme-substrate complex

A

When a substrate fits into the enzyme’s active site, which lowers the activation energy

48
Q

2 reasons why enzyme-substrate complex lowers the activation energy

A
  • If two molecules need to be joined, being attached to the enzyme holds them close together, reducing any repulsion between the molecules so they can bond more easily
  • If the enzyme is catalysing a breakdown reaction, fitting into the active site puts a strain on bonds in the substrate, so the substrate molecule breaks up more easily
49
Q

What is the lock and key model

A

When the active site and the substate have a complementary shape, when the substrate fits into the enzyme in the same way that a key fits into a lock

50
Q

What is the induced fit model

A

When the active site changes shape slightly to accommodate for the substrate

51
Q

Enzymes usually only catalyse one

A

Reaction

52
Q

The active site is determined by the enzymes

A

Tertiary structure, which is determined by the enzymes primary structure

53
Q

If the active site and substrate do not have a complementary shape what happens

A

The substrate can’t fit into the active site so the reaction can’t be catalysed

54
Q

If the tertiary structure of a protein is altered in any way the shape of the active site will change

A

meaning the substrate won’t fit into the active site and an enzyme-substrate complex won’t be formed and the enzyme will no longer be able to carry out its function

55
Q

The primary structure of a protein is determined by a

A

Gene

56
Q

If a mutation occurs in a protein coding gene it could change the

A

Tertiary structure of the enzyme produced

57
Q

Two ways to measure the rate of reaction

A
  • how fast the product is made
    -how fast the substrate is broken down
58
Q

How do you measure how fast the product is made

A

by measuring the amount of end product present at different times during the experiment

59
Q

How do you measure how fast the substrate is broken down

A

By measuring the amount of substrate molecules left at different times during the experiment the reaction rate can be calculated

60
Q

The rate of an enzyme controlled reaction increases when the

A

Temperature increases

61
Q

Why does temperature increase the rate of reaction

A

More heat means more kinetic energy so molecules move faster which makes the substrates molecules more likely to collide with the enzymes active sites the energy of these collisions also increases which means each collision is more likely to result in a reaction

62
Q

If a temperature gets too high the reaction

A

Stops

63
Q

The rise in temperature makes the enzymes molecule

A

Vibrate more

64
Q

If temperature goes above a certain level vibrations

A

Break some of the bonds that hold the enzyme in shape causing the active site to change and the enzyme and substrate to no longer fit together at this point the enzyme is denatured it no longer functions as a catalyst

65
Q

What is the optimum temperature in humans

A

37 Celsius

66
Q

What is the optimum pH in most human enzymes

A

pH 7

67
Q

Pepsin found in the stomachs optimum pH is

A

pH2 (acidic)

68
Q

Above and below the optimum pH, the H+ and OH- ions found in acids and alkalis can disrupt

A

The ionic bonds and hydrogen bonds that hold the tertiary structure in place, the enzyme becomes denatured and the active site changes

69
Q

The higher the substrate concentration the faster the

A

Reaction as more substrate molecules means a collision between substrate and enzyme is more likely and so more active sites become occupied

70
Q

What happens past the saturation point

A

There are too many substrate molecules that the enzymes have about as much as they can cope with as all active sites are full and adding more makes no difference

71
Q

The more enzyme molecules in a solution the more likely

A

A substrate molecule is to collide with one and form an enzyme-substrate complex

72
Q

If there is a limited amount of substrates there’s come a point when

A

There’s more than enough enzymes to deal with all available substrates so adding more enzymes has no further effect

73
Q

Enzyme activity can be prevented by

A

Enzyme inhibitors

74
Q

What are enzyme inhibitors

A

Molecules that bind to the enzyme they inhibit (competitive or non-competitive)

75
Q

competitive inhibitor molecules have a similar shape to

A

that of substrate molecules

76
Q

competitive inhibitors compete with

A

the substrate molecules to bind to the active site

77
Q

does a reaction take place with competitive inhibitors

A

no

78
Q

What do competitive inhibitors do

A

They block the active site so no substrate molecules can fit in it

79
Q

How much of the enzyme is inhibited depends upon

A

the relative concentrations of the inhibitor and the substrate

80
Q

non-competitive inhibitors molecules bind to

A

The enzyme away from it’s active site

81
Q

What change do non-competitive inhibitors cause

A

They cause the active site to change shape so substrate can no longer bind to it

82
Q

Why do non-competitive inhibitors not compete with the substrate molecules to bind to the enzyme’s active site

A

Because they are a different shape

Biology (13 decks)

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