Proteins and Enzymes Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is a protein?

A

A polymer built up of one or more amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is an amino acid?

A

The monomer that make up proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a peptide bond?

A

The bond between amino acids in all proteins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some types of proteins?

A

Enzymes, antibodies, transport and structural.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What letters represent the amine group in an amino acid?

A

NH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What letters represent the carboxyl group in an amino acid?

A

COOH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What letter represents a side chain in an amino acid?

A

R

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the only part of the amino acid that changes?

A

The side (R) group.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How is a dipeptide formed?

A

Condensation of two amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is a polypeptide formed?

A

Condensation of many amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the name for the test for proteins?

A

The Biuret test.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How do we conduct the Biuret test for proteins?

A

1) Add biuret reagent (copper sulphate and sodium hydroxide)

2) if protein is present, colour turns purple.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the primary structure of proteins?

A

The sequence of amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What bonds are present in the primary structure of proteins?

A

Peptide bonds.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the secondary structure of proteins?

A

The long chains of amino acids fold into regions with repeating patterns (alpha helix and beta pleated sheet).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What bonds are present in the secondary structure of proteins?

A
  • Peptide bonds.

- Hydrogen bonds.

17
Q

What is the tertiary structure of proteins?

A

The final 3D resting shape of the protein.

18
Q

What bonds are present in the tertiary structure of proteins?

A
  • Peptide bonds.
  • Hydrogen bonds.
  • Ionic bonds.
  • Disulphide bridges.
19
Q

What is the quaternary structure of proteins?

A

Proteins made of more than one polypeptide chain (e.g. haemoglobin).

20
Q

What bonds are present in the quaternary structure of proteins?

A
  • Peptide bonds.
  • Hydrogen bonds.
  • Ionic bonds.
  • Disulphide bridges.
21
Q

What is the ideal answer to a protein shape question (enzymes/antibodies)?

A

The tertiary structure of the active site is complementary to the shape of the substrate and so forms an enzyme-substrate complex/ antibody-enzyme complex.

22
Q

How can a mutation cause a protein to become non-functional?

A

Changes the primary structure and therefore the tertiary structure. This changes the active site shape so substrate is no longer complementary. this means no enzyme-substrate complex can be formed.

23
Q

How can denaturation lead to a non-functional protein?

A

Changes ionic bonds so changes tertiary structure. This changes the shape of the active site so the substrate is no longer complimentary. This means no enzyme-substrate complex can be formed.

24
Q

What is an enzyme?

A

A biological catalyst that lowers the activation energy of the reaction is catalyses.

25
Q

What type of protein are enzymes?

A

Globular proteins.

26
Q

What is the lock and key hypothesis of enzyme action?

A

It states that the shape of the active sites of enzymes are exactly complementary to the shape of the substrate. This means that when a substrate molecule collides with it complementary enzyme, the substrate will fit into the active site and an enzyme-substrate complex will form.

27
Q

What is the induced fit hypothesis of enzyme action?

A

It states that the shape of the active sites are not exactly complimentary, but change shape in the presence of a specific substrate to become complementary. When a substrate molecule collides with an enzyme, if its composition is specifically correct, the shape of the enzyme’s active site will change so that the substrate fits into it and an enzyme-substrate complex can form.

28
Q

What factors can affect the rate of enzyme catalysed reactions?

A
  • Temperature.
  • pH.
  • Enzyme concentration.
  • Substrate concentration.
  • Inhibitors.
29
Q

What is meant by the term denatured?

A

A permanent change to the active site which means no more enzyme-substrate complexes are formed.

30
Q

What effect does temperature have on enzyme action?

A

As the temperature increases the molecules vibrate more so more collisions and more E_S complexes are formed (lower activation energy). This continues until optimum temperature.
If temperature gets too high, internal bonds break and the shape of the active site changes. this means no E-S complexes can be formed; the enzyme is denatured.

31
Q

What effect does pH have on enzyme action?

A

Enzymes have an optimum pH. If you increase or decrease the pH away from the optimum, the enzyme activity will decrease.

32
Q

Why does the pH level effect enzyme action?

A

The OH- (alkali) or H+ (acid) will interact with the hydrogen bonds or ionic bonds. This changes the shape of the tertiary structure and therefore the active site of the enzyme. Fewer/no E-S complexes are formed. The enzyme is denatured.

33
Q

How does enzyme concentration affect enzyme activity?

A

As you increase the enzyme concentration, the rate of reaction increases because there are more collisions and more E-S complexes formed. Once the substrate runs out, adding more enzymes will make no difference to the rate of reaction.

34
Q

How does substrate concentration affect enzyme activity?

A

As you increase substrate concentration, the rate of reaction increases because there are more collisions and more E-S complexes formed. This continues until all active sites are occupied, then the enzyme concentration is the limiting factor (adding more substrate will make no difference).

35
Q

What affect do competitive inhibitors have on enzyme action?

A

Competitive inhibitors have a similar shape to the substrate. They can also bind to the active site and prevent the E-S complex forming. The proportion of substrate to competitive inhibitor will affect how much the rate of reaction changes.

36
Q

What affect do non-competitive inhibitors have on enzyme action?

A

Non-competitive inhibitors bind to the enzyme but not at the active site. This changes the shape of the active site so no more E-S complexes can form. Changing the concentration of substrate won’t make any difference.