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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
In SDS PAGE, what does SDS do?
It binds to proteins and equalises the charge to mass ratio
26
In SDS PAGE, what does polyacrylamide do?
It forms a highly cross-linked gel that restricts protein movement.
27
In gel filtration, what is a mobile phase?
A phase that carries the sample throughout the procedure
28
In gel filtration, what is a stationary phase?
A matrix/ phase that restricts the movement of the sample
29
How can a protein/ polypeptide be hydrolyzed into its constituent amino acids?
Incubation in 6M hydrochloric acid at 120°C for 24 hours
30
How many naturally occurring amino acids are there?
Approx 20
31
What is a Zwitterion?
a compound which is electrically neutral but carries positive and negative charges on different atoms
31
What is a Zwitterion?
a compound which is electrically neutral but carries positive and negative charges on different atoms
32
α-amino acids are...
zwitterions
33
Why are α-amino acids called α-amino acids?
They have their amino group on the α-carbon
34
In amino acids at physiological pH, amino groups are... | protonated/ deprotonated
protonated
35
In amino acids at physiological pH, amino groups are... | protonated/ deprotonated
protonated
36
In amino acids at physiological pH, carboxyl groups are... | protonated/ deprotonated
deprotonated
36
In amino acids at physiological pH, carboxyl groups are... | protonated/ deprotonated
deprotonated
37
With the exception of [amino acid], all amino acids recovered from proteins are optically active.
glycine
38
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
All of the above
39
"A" stands for which amino acid? 1. glycine 2. phenylalanine 3. alanine 4. tryptophan 5. glutamic acid
alanine
40
"W" stands for which amino acid?
tryptophan
41
"E" stands for which amino acid?
glutamic acid
42
"N" stands for which amino acid?
asparagine
43
"R" stands for which amino acid?
arginine
44
"D" stands for which amino acid?
aspartic acid
45
The amino acids that absorb UV light are...
* Phenylalanine * Tyrosine * Tryptophan
46
The amino acids that absorb UV light do so because of the presence of...
an aromatic group/ benzene ring
47
The first reaction of glycolysis is catalysed by the enzyme...
48
Mitochondrial DNA encodes for [amount] genes in total.
49
When mercaptoethanol is added to a protein solution, it removes...
50
A peptide bond is formed by a ... reaction.
51
The degree of rotation of light is measured using an instrument called a ...
polarimeter
52
The term "chiral" refers to...
an object that is non-super imposable on its mirror image
53
The term "chiral" refers to...
an object that is non-super imposable on its mirror image
54
All optically active molecules are ...
asymmetrical
55
Mirror images of a molecule that are non-super imposable on each other are called...
enantiomers/ optical isomers
56
In Fischer projections, horizontal bonds extend ...
towards the viewer.
57
In Fischer projections, vertical bonds extend...
away from the viewer
58
Amino acids in proteins are always the ...-configuration.
L-configuration
59
Give an example where chirality of amino acids is important.
thalidomide
60
Which group of an amino acid determines its structure and physical characteristics?
the R group
61
Lysine may be modified into ... after being assembled into a protein
5-hydroxylysine
61
Lysine may be modified into ... after being assembled into a protein
5-hydroxylysine
62
Proline can be modified into ... after being assembled into a protein.
4-hydroxyproline
63
The charge on amino acids can change with a change in ...
pH
64
All amino acids are ... acids.
weak acids
65
The sulfhydryl group in ... gives this amino acid the ability to make disulfide bonds.
cysteine
66
A polypeptide is least solube when it has a ... charge.
neutral
67
At high pH, all ionizable groups will have a ... charge.
negative
68
At low pH, all ionizable groups will have a ... charge.
positive
69
The isoelectric point of an amino acid is aka ...
the Zwitterionic point
70
An anion is ... charged.
negatively
70
An anion is ... charged.
negatively
71
A cation is ... charged.
positively
72
The pI is the protein's...
isoelectric/ zwitterionic point
73
The pK₂ is the protein's ... point.
anionic
74
The pK₁ is a protein's ... point.
cationic
75
In general, pK₁ occurs at a pH of ...
2
76
In general, pK₂ occurs at a pH of...
9.4
77
A ... is a macromolecule that has both anionic and cationic character.
polyampholyte

Biochemistry (4 decks)

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