Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 1 - MCBG > 1. Proteins > Flashcards

1. Proteins Flashcards

1
Q

What are proteins?

A

Polypeptides made up of amino acids joined covalently together.

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

Whar does the folding of proteins depend on?

A

the chemical and physical properties of the amino acids

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

What determines the amino acid sequence?

A

The amino acid sequence of a protein is encoded by a gene and determined by the nucleotide sequence of that gene.

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

How are amino acids classified?

A

They are classified according of the chemical properties of the R groups

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

What determines the acid base behaviour of the amino acids?

A

R groups

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

What is an amino acid residue?

A

An amino acid residue is what remains of an amino acid after it has been joined by a peptide bond to form a protein

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

List 7 chemical properties of R group that help classify amino acids

A 
Hydrophobic
Hydrophilic 
Polar
Non polar
Acidic
Basic
Neutral
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

List 2 physical properties of r groups that help classify amino acids?

A

Aliphatic

Aromatic

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

What does high pK indicate?

A

Positively charged groups

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

What does low pK indicate?

A

Negatively charged groups

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

What happens if the pH of the solution < the pK value?

A

the group will be protonated

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

What happens if the pH of the solution > the pK value?

A

the group will be deprotonated

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

Define primary structure

A

The linear amino acid sequence of the polypeptide chain

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

Define secondary structure

A

Local spatial arrangement of polypeptide backbone - conformations like helixes

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

Define tertiary structure

A

The overall 3 dimensional configuration of the protein

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

Define quaternary structure

A

Association between different polypeptides to form a multi subunit protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Define peptide bond formation

A

The linking of two amino acids accompanied by the abstraction of a molecule of water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

List two feature of peptide bonds

A

Planar - Ca, C, O, N, H and Ca all lie in the same plane

Rigid - C-N peptide bond has partial double bond characteristics
- Unable to rotate – contributes to planarity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does a trans on formation of the peptide bond mean?

A

Alpha Carbons of the two amino acid residues on opposite sides of peptide bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does a cis transformation of a peptide bond mean?

A

Alpha Carbons of the two amino acid residues on the same sides of peptide bond

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Are the Bonds on either side of the peptide bond are free to rotate?

A

Yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does the amino acid sequence of a protein determine?

A
  • The way in which the polypeptide chain folds

* The physical characteristics of the protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the isoelectric point of proteins?

A

The isoelectric point, pI, of a protein is the pH at which there is no overall net charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the pI of basic proteins and why?

A

pI > 7

Contain many positively charged (basic) amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the pI of acidic proteins an why?

A

pI < 7

Contain many negatively charged (acidic) amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does is meant if the pH < pI ?

A

protein is protonated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does it mean if pH > pI

A

protein is deprotonated

28
Q

Define Peptides/oligopeptides

A

few amino acids in length

29
Q

Define Polypeptides/proteins

A

Many amino acids

30
Q

What are conjugated proteins?

A

When proteins contain covalently linked chemical components in addition to amino acids

31
Q

Give an example of a conjugated protein

A

Lipoproteins

32
Q

What causes the formation of alpha helixes?

A

H-bonds between N-H and C=O

33
Q

Which proteins are strong helix formers?

A

Small hydrophobic residues such as Ala and Leu

34
Q

Why does Pro act as a helix breaker?

A

because the rotation
around the N-C a
bond is impossible

35
Q

Why does Gly act as a helix breaker

A

because the tiny R-

group supports other conformations

36
Q

Describe the beta pleated sheet

A

Antiparallel b-sheet: adjacent b-strands run in opposite directions, with multiple inter-strand H-bonds stabilizing the structure.

37
Q

What is the role of fibrous proteins?

A

support, shape, protection

38
Q

What is the role of globular proteins?

A

catalysis, regulation

39
Q

Describe the shape of fibrous proteins

A

Long strands or sheets

40
Q

Describe the shape of globular proteins

A

Compact shape

41
Q

Describe the structure of fibrous proteins

A

Single type of repeating secondary structure

42
Q

Describe the structure of globular proteins

A

Several types of secondary structure

43
Q

Give an example of a fibrous protein

A

collagen

44
Q

Give an example of a globular protein

A

Haemoglobin

45
Q

What is a motif?

A

Folding patterns containing 1 or more elements of secondary structure

46
Q

What are domains?

A

Part of a polypeptide chain that fold into a distinct shape. Often has a specific functional role

47
Q

Describe the folding of water soluble proteins

A

Polypeptide chains fold to so that hydrophobic side chains are
buried and polar, charged chains are on the surface

48
Q

What are the forces present in primary structure?

A

Covalent(peptide)

49
Q

What are the forces present in secondary structure?

A

Hydrogen bonds

50
Q

What are the forces present in tertiary structure?

A 
Covalent
Hydrogen bonds
Ionic bonds
Disulphides bridges
Van der Waals
Hydrophobic forces
51
Q

What a re the forces present in quaternary structure?

A 
Covalent
Ionic, 
Disulphides bridges 
H-bonds, 
Van der Waals, 
hydrophobic
52
Q

Between which group are disulphides bridges formed?

A

Between 2 cysteine groups

53
Q

What type of bond is a disulphide bridge?

A

Covalent bond

54
Q

What can break disulphide bridges?

A

Reducing agents

55
Q

What happens to most proteins with disulphide bridges and why?

A

Most proteins with disulphide bonds are secreted.

Extracellular conditions are harsher for proteins so most secreted have strong disulphides bonds which helps to maintain structure

56
Q

How are electrostatic interactions formed?

A

Formed between charged groups

57
Q

How are hydrogen bonds formed?

A

Formed between electronegative atom and a hydrogen bound to another electronegative atom

58
Q

What is the hydrophobic effect?

A

Interaction between hydrophobic side chains. Due to displacement of water

59
Q

What is Van der Waals?

A

Dipole-dipole interactions formed because of transient location of electrons at any given moment .

  • Very weak forces.
  • Intrinsic to any bond type
60
Q

When are van der Waals forces important?

A

Important when surfaces of 2 large molecules come together

61
Q

What is native conformation?

A

A normally folded protein that is functional is said to in the native conformation

62
Q

What is protein denaturation?

A

Disruption of protein structure is known as denaturation.
Caused by breaking of forces that hold proteins together.
Losing the native conformation.

63
Q

What 3 things cause protein denaturation and how?

A

Heat - Increased vibrational energy

pH - Alters ionization states of amino acids Changes ionic/H-bonds

Detergents/organic solvents - Disrupt hydrophobic interactions

64
Q

How do proteins fold?

A

The folding process must be ordered
Each step involves localised folding and with stable conformations maintained
Driven by the need to find the most stable conformation

65
Q

What happens when there is protein misfolding?

A

Altered conformation of a normal human protein promotes converts existing protein into diseased state

Semester 1 - MCBG (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions