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Biochemistry > Proteins > Flashcards

Proteins Flashcards

1
Q

What is gel filtration used for?

A

To separate small molecules from large molecules

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2
Q

What is another name for gel filtration?

A

Size exclusion chromatography

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3
Q

In gel filtration, which molecule will elute first?

A

The larger molecule

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4
Q

In gel filtration, which molecule will elute last?

A

The smaller molecule

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5
Q

Separation based on…

What is the principle of gel filtration?

A

Separation based on molecular size

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6
Q

In gel filtration, which molecules can enter the bead pores?

A

Small molecules

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7
Q

Name 3 substances used in the column in gel filtration?

A

Dextran, agarose, and polyacrylamide

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8
Q

In gel filtration, why do large molecules elute out of the column first?

A

Large molecules have a smaller volume to move through, because they cannot fit inside the pores of the beads.

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9
Q

What determines a protein’s function?

A

The protein conformation (3D shape)

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10
Q

Name the 5 types of protein structure.

A
  • Primary
  • Secondary
  • Tertiary
  • Quartenary
  • Supramolecular
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11
Q

What is meant by the primary structure of a protein?

A

The sequence of amino acid residues joined by peptide bonds

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12
Q

Name 2 chemicals which may denature proteins.

A

Urea and Guanidine Hydrochloride

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13
Q

What can denature a protein?

A

High temperatures and certain chemicals, such as urea

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14
Q

What does the Anfinsen paradigm state?

A

The information needed for correct protein folding is found within the amino acid residue sequence

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15
Q

What does ribonuclease do?

A

It catalyzes the hydrolysis of RNA

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16
Q

What did Anfinsen do in his experiment with proteins?

A
  • He denatured proteins, using Guanidine Hydrochloride and mercaptoethanol, which broke the disulfide bonds in the protein.
  • He then found that, after he removed the GnHCl, the proteins refolded.
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17
Q

What are the 2 factors affecting protein conformation?

A
  • Amino acid residue sequence
  • The physical (temperature) and chemical (pH) conditions of the protein’s environment
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18
Q

What is denaturation?

A

When a protein unravels and loses its native conformation

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19
Q

What did Anfinsen’s paradigm show?

A

Protein folding can occur in vitro

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20
Q

What are chaperonins?

A

Proteins that help other proteins to fold properly

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21
Q

What are the two functions of chaperonins?

A
  • Stabilise new proteins to ensure correct folding
  • Help refold damaged proteins
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22
Q

What does SDS PAGE stand for?

A

Sodium
Dodecyl
Sulfate
Poly
Acrylamide
Gel
Electrophoresis

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23
Q

What is electrophoresis?

A

The movement of charged molecules in an electric field, towards the oppositely-charged electrode

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24
Q

Gel electrophoresis is a technique used to…

A

Separate nucleic acids and proteins, using an electric current applied to a gel matrix

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25
Q

In SDS PAGE, what does SDS do?

A

It binds to proteins and equalises the charge to mass ratio

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26
Q

In SDS PAGE, what does polyacrylamide do?

A

It forms a highly cross-linked gel that restricts protein movement.

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27
Q

In gel filtration, what is a mobile phase?

A

A phase that carries the sample throughout the procedure

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28
Q

In gel filtration, what is a stationary phase?

A

A matrix/ phase that restricts the movement of the sample

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29
Q

How can a protein/ polypeptide be hydrolyzed into its constituent amino acids?

A

Incubation in 6M hydrochloric acid at 120°C for 24 hours

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30
Q

How many naturally occurring amino acids are there?

A

Approx 20

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31
Q

What is a Zwitterion?

A

a compound which is electrically neutral but carries positive and negative charges on different atoms

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31
Q

What is a Zwitterion?

A

a compound which is electrically neutral but carries positive and negative charges on different atoms

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32
Q

α-amino acids are…

A

zwitterions

33
Q

Why are α-amino acids called α-amino acids?

A

They have their amino group on the α-carbon

34
Q

In amino acids at physiological pH, amino groups are…

protonated/ deprotonated

A

protonated

35
Q

In amino acids at physiological pH, amino groups are…

protonated/ deprotonated

A

protonated

36
Q

In amino acids at physiological pH, carboxyl groups are…

protonated/ deprotonated

A

deprotonated

36
Q

In amino acids at physiological pH, carboxyl groups are…

protonated/ deprotonated

A

deprotonated

37
Q

With the exception of [amino acid], all amino acids recovered from proteins are optically active.

A

glycine

38
Q

Amino acids consist of…
1. a central carbon atom (α carbon)
2. an amino group
3. a carboxy group
4. a side chain (R group)
5. all of the above

A

All of the above

39
Q

“A” stands for which amino acid?
1. glycine
2. phenylalanine
3. alanine
4. tryptophan
5. glutamic acid

A

alanine

40
Q

“W” stands for which amino acid?

A

tryptophan

41
Q

“E” stands for which amino acid?

A

glutamic acid

42
Q

“N” stands for which amino acid?

A

asparagine

43
Q

“R” stands for which amino acid?

A

arginine

44
Q

“D” stands for which amino acid?

A

aspartic acid

45
Q

The amino acids that absorb UV light are…

A
  • Phenylalanine
  • Tyrosine
  • Tryptophan
46
Q

The amino acids that absorb UV light do so because of the presence of…

A

an aromatic group/ benzene ring

47
Q

The first reaction of glycolysis is catalysed by the enzyme…

A
48
Q

Mitochondrial DNA encodes for [amount] genes in total.

A
49
Q

When mercaptoethanol is added to a protein solution, it removes…

A
50
Q

A peptide bond is formed by a … reaction.

A
51
Q

The degree of rotation of light is measured using an instrument called a …

A

polarimeter

52
Q

The term “chiral” refers to…

A

an object that is non-super imposable on its mirror image

53
Q

The term “chiral” refers to…

A

an object that is non-super imposable on its mirror image

54
Q

All optically active molecules are …

A

asymmetrical

55
Q

Mirror images of a molecule that are non-super imposable on each other are called…

A

enantiomers/ optical isomers

56
Q

In Fischer projections, horizontal bonds extend …

A

towards the viewer.

57
Q

In Fischer projections, vertical bonds extend…

A

away from the viewer

58
Q

Amino acids in proteins are always the …-configuration.

A

L-configuration

59
Q

Give an example where chirality of amino acids is important.

A

thalidomide

60
Q

Which group of an amino acid determines its structure and physical characteristics?

A

the R group

61
Q

Lysine may be modified into … after being assembled into a protein

A

5-hydroxylysine

61
Q

Lysine may be modified into … after being assembled into a protein

A

5-hydroxylysine

62
Q

Proline can be modified into … after being assembled into a protein.

A

4-hydroxyproline

63
Q

The charge on amino acids can change with a change in …

A

pH

64
Q

All amino acids are … acids.

A

weak acids

65
Q

The sulfhydryl group in … gives this amino acid the ability to make disulfide bonds.

A

cysteine

66
Q

A polypeptide is least solube when it has a … charge.

A

neutral

67
Q

At high pH, all ionizable groups will have a … charge.

A

negative

68
Q

At low pH, all ionizable groups will have a … charge.

A

positive

69
Q

The isoelectric point of an amino acid is aka …

A

the Zwitterionic point

70
Q

An anion is … charged.

A

negatively

70
Q

An anion is … charged.

A

negatively

71
Q

A cation is … charged.

A

positively

72
Q

The pI is the protein’s…

A

isoelectric/ zwitterionic point

73
Q

The pK₂ is the protein’s … point.

A

anionic

74
Q

The pK₁ is a protein’s … point.

A

cationic

75
Q

In general, pK₁ occurs at a pH of …

A

2

76
Q

In general, pK₂ occurs at a pH of…

A

9.4

77
Q

A … is a macromolecule that has both anionic and cationic character.

A

polyampholyte

Biochemistry (4 decks)

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