Proteins Flashcards

1
Q

Biological roles of proteins include

A

Structure- collagen, keratin
Transport- membrane transport

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2
Q

What determines amino acid properties

A

Side chain R

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3
Q

What is the smallest amino acid to larger

A

Glycine, alanine, valine, leucine

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4
Q

Why are amino acid hydrophobic

A

CH3 doesn’t interact with water

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5
Q

Phenylanine is

A

Hydrophobic

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6
Q

Hydrophilic and charged amino acids

A

Aspartame
Glutamate
Asparagine
Glutamine
Serine

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7
Q

Cysteine can be used for

A

Disulfide bonds

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8
Q

Transmembrane proteins function

A

Move materials through bilayer

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9
Q

Special features of amino acids

A

Methionine- 1st amino acid in protein sequence determined by DNA start codin- ATG
Cytosine- disulphide bond formation

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10
Q

Amino acid modification is

A

Serine and threonine- due to hydroxyl group
O linked glycosylation
Reversible phosphorylation
Asparagine- N linked glycosylation
Proline- ring- forces bend in protein structure

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11
Q

Name of reaction of peptide bond formation

A

Condensation reaction

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12
Q

Can free rotation occur in peptide bond formation

A

Yeah

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13
Q

Amino acid sequence determines

A

Protein structure

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14
Q

IY structure is the only interaction between amino acids and

A

Peptide bond

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15
Q

What is secondary structure

A

Local structure of polypeptide chain
Bonding is due to hydrogen bonding- way protein starts to fold

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16
Q

Can secondary structure be easily broken

A

Alpha helix
Beta sheet

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17
Q

Alpha helix structure features

A

Rod like structure
Coiled peptide chain
R groups extend outwards from axis
H bonding between CO and NH4 residues away

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18
Q

Alpha helix is intertwined with

A

Myosin
Tropomyosin
Muscle fibrin in blood clots
Keratin in hair

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19
Q

Beta sheet features

A

Polypeptide chain is extended
H bonding between CO and NH on different polypeptide strands
Strands run parallel or anti parallel
Anti parallel strands connected by B turns
Silk strong structure

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20
Q

What is tertiary structure

A

Side chain R group interactions
Most are weak, non covalent interactions but stabilise and fold proteins- globular proteins

21
Q

Many globular proteins are

A

Carriers- enzymes and receptors

22
Q

Types of tertiary structure bonding

A

H bonding
Electrostatic interactions between charged groups
Hydrophobic interactions
Van der waals forces
Disulphide bonds- between cysteine residues

23
Q

Quaternary structure is

A

Complex of 2 or more separate polypeptide chains.
Interaction between subunits
Non covalent and covalent interactions
Allosteric properties- can change shape
Haemoglobin
4 subunits interacting

24
Q

What does protein denaturation do

A

Disrupts bonding

25
Q

Heat breaks what type of bonding

A

Weak

26
Q

PH affects

A

Bonding
Electrostatic interactions

27
Q

Chaotropic agents

A

Form H binds with amino acids and disrupt existing H bonds and hydrophobic interactions

28
Q

Is denaturation of tertiary structure reversible

A

Yes

29
Q

Protein folding involves what type of protein

A

Chaperone

30
Q

Gene mutation causes

A

Change in AA sequence

31
Q

Substitutions can cause a

A

Conservative- same type of AA
Radical- different type of AA

32
Q

Substitutions alter

A

Ligand binding or enzyme activity
Affect shape of proteins

33
Q

Insertions and deletions can

A

Cause loss of protein function
Deletions can determine binding site residues

34
Q

X-ray crystallography

A

Complete 3D structure

35
Q

Collagen triple helix

A

3 amino acids per turn

36
Q

Scurvy is

A

Vitamin C deficiency

37
Q

Prior diseases is

A

Fibrous forms of protein aggregate

38
Q

Scrapie susceptibility is

A

Already formed fibrils act as template

39
Q

ARR type 1 is resistant to

A

Scrapie

40
Q

VRQ type is susceptible to

A

Sheep

41
Q

Why does the scrapie form not propagate well

A

It’s resistant

42
Q

Proteomics is

A

Study protein profile of cell or tissue

43
Q

Qualitative is

A

Difference in amino acid sequence

44
Q

Quantitative is

A

Increase or decrease in proteins

45
Q

Non biased approach

A

Looks at all proteins

46
Q

Proteins are separated based on their

A

Size
Charge

47
Q

How are proteins separated

A

Isoelectric focusing
1st step- proteins move in pH gradient and when they reach isoelectric point they may stop
2nd step- SDS page

48
Q

Advantages of 2D structure

A

Very good resolution
Separate complex protein mixtures