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Proteins and Enzymes Flashcards

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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
Haemoglobin is compact and an insoluble protein which makes it easy to
Transport, and carry oxygen around the body
26
Enzymes often have a role in
Metabolism
27
28
Do enzymes break down or synthesise large molecules
Both
29
Are enzymes soluble or insoluble
soluble
30
Antibodies are involved in the
Immune response
30
Where are antibodies found
In the blood
31
What are antibodies made up of
2 light (short) polypeptide chains and two heavy (long) polypeptide chains bonded together
32
Antibodies have variable regions which means that the
Amino acid sequences in these regions vary greatly
33
Channel proteins contain hydrophobic and hydrophilic amino acids causing the protein to
Fold up and form a channel
34
Structural proteins consist of
long polypeptide chains lying parallel to each other with cross links between them.
35
Collagen is a great supportive tissue in animals because
It has three polypeptide chains tightly coiled together, which makes it strong
36
Food test to identify protein
Biuret Test
37
For the protein test to take place the test solution must be
Alkaline, so first add a few drops of sodium hydroxide solution
38
What is added to test solution to test for protein
Coper sulfate solution
39
If a protein is present the solution turns from
Blue to purple
40
Enzymes are
Biological catalysts
41
Enzymes catalyse metabolic reactions at both
Cellular level (respiration), and for the organism as a whole (digestion)
42
Enzyme action can occur
Intracellular or Extracellular
43
What is an active site
The part of the enzyme where substrate molecules bind to, it has a specific shape
44
Enzymes are highly specific due to
Their tertiary structure
45
What is activation energy
The certain amount of energy needed to be supplied to the chemicals before the reaction will start, often provided as heat energy
46
Enzymes lower the
Amount of activation energy that's needed often making reactions occur at lower temperature
47
What is the enzyme-substrate complex
When a substrate fits into the enzyme's active site, which lowers the activation energy
48
2 reasons why enzyme-substrate complex lowers the activation energy
- 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
What is the lock and key model
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
What is the induced fit model
When the active site changes shape slightly to accommodate for the substrate
51
Enzymes usually only catalyse one
Reaction
52
The active site is determined by the enzymes
Tertiary structure, which is determined by the enzymes primary structure
53
If the active site and substrate do not have a complementary shape what happens
The substrate can’t fit into the active site so the reaction can’t be catalysed
54
If the tertiary structure of a protein is altered in any way the shape of the active site will change
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
The primary structure of a protein is determined by a
Gene
56
If a mutation occurs in a protein coding gene it could change the
Tertiary structure of the enzyme produced
57
Two ways to measure the rate of reaction
- how fast the product is made -how fast the substrate is broken down
58
How do you measure how fast the product is made
by measuring the amount of end product present at different times during the experiment
59
How do you measure how fast the substrate is broken down
By measuring the amount of substrate molecules left at different times during the experiment the reaction rate can be calculated
60
The rate of an enzyme controlled reaction increases when the
Temperature increases
61
Why does temperature increase the rate of reaction
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
If a temperature gets too high the reaction
Stops
63
The rise in temperature makes the enzymes molecule
Vibrate more
64
If temperature goes above a certain level vibrations
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
What is the optimum temperature in humans
37 Celsius
66
What is the optimum pH in most human enzymes
pH 7
67
Pepsin found in the stomachs optimum pH is
pH2 (acidic)
68
Above and below the optimum pH, the H+ and OH- ions found in acids and alkalis can disrupt
The ionic bonds and hydrogen bonds that hold the tertiary structure in place, the enzyme becomes denatured and the active site changes
69
The higher the substrate concentration the faster the
Reaction as more substrate molecules means a collision between substrate and enzyme is more likely and so more active sites become occupied
70
What happens past the saturation point
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
The more enzyme molecules in a solution the more likely
A substrate molecule is to collide with one and form an enzyme-substrate complex
72
If there is a limited amount of substrates there’s come a point when
There’s more than enough enzymes to deal with all available substrates so adding more enzymes has no further effect
73
Enzyme activity can be prevented by
Enzyme inhibitors
74
What are enzyme inhibitors
Molecules that bind to the enzyme they inhibit (competitive or non-competitive)
75
competitive inhibitor molecules have a similar shape to
that of substrate molecules
76
competitive inhibitors compete with
the substrate molecules to bind to the active site
77
does a reaction take place with competitive inhibitors
no
78
What do competitive inhibitors do
They block the active site so no substrate molecules can fit in it
79
How much of the enzyme is inhibited depends upon
the relative concentrations of the inhibitor and the substrate
80
non-competitive inhibitors molecules bind to
The enzyme away from it's active site
81
What change do non-competitive inhibitors cause
They cause the active site to change shape so substrate can no longer bind to it
82
Why do non-competitive inhibitors not compete with the substrate molecules to bind to the enzyme's active site
Because they are a different shape

Biology (13 decks)

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