Proteins Flashcards

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1
Q

What are proteins also called?

A

Polypeptides/polymers

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2
Q

How are proteins structured?

A

Long chains of amino acids

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3
Q

What do all amino acids contain?

A
  • carbon
  • hydrogen
  • oxygen
  • nitrogen
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4
Q

What do many amino acids also contain?

A

Sulfur

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5
Q

How is an amino acid structured?

A

An amino group (NH2)
A central C with a H
A variable R group attached to the central C
A carboxyl group (COOH)

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6
Q

How many different R groups are there giving the same number of different amino acids?

A

20

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7
Q

What is the simplest amino acid?

A

Glycine: R=H

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8
Q

What is the the more complex amino acid example?

A

Cysteine- R=CH^2SH

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9
Q

What bonds amino acids?

A

Peptide bond

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10
Q

How is a peptide bond formed?

A

Condensation reaction

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11
Q

What do two amino acids combine to form?

A

A dipeptide

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12
Q

What groups does a peptide bond form between?

A

One amino acid’s carboxyl group and the other’s amino group.

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13
Q

Three or more amino acids joined by a peptide form what?

A

Polypeptide

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14
Q

What is the primary structure of a polypeptide?

A

A long chain of amino acids

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15
Q

What happens if the sequence changes due to DNA mutation in a primary structure?

A

The protein will be non-functional

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16
Q

What are the two secondary structures and how are they formed?

A

The polypeptide chain twists to form

  • an alpha helix
  • or a beta pleated sheet
17
Q

What maintains the secondary structure’s shape?

A

Hydrogen bonds between the peptide bonds.

18
Q

What make up proteins?

A

Amino acid monomers

19
Q

What is a tertiary structure’s shape?

A

Secondary structure folded into a specific 3d shape

20
Q

What 3 types of bonds hold together tertiary structure?

A
  • Hydrogen bonds between R groups containing O- and H+
  • ionic bonds between R groups containing oppositely charged ions.
  • disulfide bonds between sulfur containing R groups. Very stable, occur least often.
21
Q

What are hydrophobic interactions?

A

Interactions between two non-polar R gtoups. Within protein, amino acids with non polar R groups move away from aqueous environment to form hydrophonic centre at protein molecule interior.

22
Q

How are quaternary formed?

A

2 or more polypeptide chains combined. Held by same bonds as tertiary.

23
Q

What is an example of quaternary and what is it made up of?

A

Haemoglobin. 4 tertiary bonded together- 2 alpha and 2 beta chains

24
Q

What are the two protein types and their functions?

A

Fibrous (structural)

Globular (biochemical)

25
Q

What structure do fibrous proteins have?

A

Secondary

26
Q

How are fibrous formed/structured?

A

Polypeptide chains twisted to form long strands

27
Q

Are fibrous insoluble or soluble?

A

Insoluble- can’t dissolve

28
Q

What is the structure of the fibrous protein collagen?

A

3 intertwined chains

29
Q

What is the function of the fibrous protein collagen?

A

Main connective tissue in body, found in ligaments, tendons and cartilage

30
Q

What is the fibrous protein keratin’s structure?

A

Two intertwined chains

31
Q

What are keratin’s two functions?

A
  • main component of hard structures such as hair, nails and hooves
  • part of skin cells, preventing pathogen entry.
32
Q

What structure do globular proteins have?

A

Tertiary or quaternary

33
Q

Is globular soluble or insoluble?

A

Soluble

34
Q

What are the possible biochemical functions of globular proteins? (4)

A
  • Enzymes
  • transport proteins such as haemoglobin and myoglobin.
  • hormones- such as oestrogen and insulin.
  • antibodies
35
Q

What is denaturing?

A

If the bonds that maintain a protein’s shape are broken, the protein will stop working properly= denatured.

36
Q

What factors can denature proteins?

A
Changes in:-
-temp
-pH
-salt concentration
(Specific conditions vary from protein to protein).
37
Q

What effect does denaturing have on fibrous?

A

Loses structural strength

38
Q

What effect does denaturing have on globular?

A

Becomes insoluble and inactive

39
Q

What is the test for proteins?

A

Add biuret agent (copper sulfate and sodium hydroxide).

A change from pale blue to lilac/purple = positive.