Brainscape's Knowledge GenomeTM

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


See full index

Cell Biology and Genetics > Proteins > Flashcards

Proteins Flashcards

1
Q

What is the structure of an amino acid?

A

Central carbon atom, covalently bound to

  • Amino group
  • Carboxyl group
  • Hydrogen atom
  • R group (side chain)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do amino acids ionise?

A

Amino group gains hydrogen ion
NH2 + H+ —–> NH3+

Carboxyl group gives up hydrogen ion
COOH —–> COO- + H+

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

Which group in the amino acid is acidic?

A

The carboxyl group

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

Which group in the amino acid is basic?

A

The amino group

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

How are amino acids classified? Why?

A

Based on the properties of the R groups

Because in polypeptide chains, only the hydrogen atom and the R group of the amino acids remains

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

What is an amino acid residue?

A

What remains of an amino acid after it has been jointed to another amino acid

  • R group
  • hydrogen atom
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the types of properties of the R group?

A

Chemical properties

Physical properties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the possible chemical properties of the R group?

A

Polar/non-polar

Hydrophobic/hydrophilic

Acidic/basic/neutral

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

What are the possible physical properties of the R group?

A

Aliphatic/aromatic

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

What does the pKa value of amino acids measure?

A

How acidic the amino acids are

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

What does a low pKa value mean?

A

The amino acid is more acidic

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

What does a high pKa value mean?

A

The amino acid is less acidic

more basic

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

What happens to the amino acid if pH > pKa? Why?

A

Higher pH means fewer hydrogen ions present
amino acid gives up hydrogen ions
becomes deprotonated

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

What happens to the amino acid if pH < pKa? Why?

A

Lower pH means more hydrogen ions present
amino acid takes up hydrogen ions
becomes protonated

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

What is physiological pH?

A

7.4

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

What is the primary structure of a protein?

A

Amino acids joined together in a linear chain

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

What reaction occurs when two amino acids are joined together?

A

amino acid1 + amino acid 2 —–> polypeptide + water

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

What bond joins two amino acids together?

A

Peptide bond

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

What is the amino terminus of a polypeptide?

A

The amino group NH2 end of the polypeptide chain

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

What is the carboxyl terminus of a polypeptide?

A

The carboxyl group COOH end of the polypeptide chain

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

What are the properties of peptide bonds?

A

Planar

Rigid

Trans conformation

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

What is meant by peptide bonds being planar?

A

The central carbon atom
N-H
C=O

are all in the same plane

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

What is meant by peptide bonds being rigid?

A

No rotation about the peptide bond

24
Q

What atoms are involved in a peptide bond?

A

C-N

C from C=O
N from N-H

25
Q

What is meant by the peptide bond having a trans conformation?

A

Heavier groups are on opposite sides of the peptide bond

the heavier groups are the central carbon atom, R group, H atom altogether

26
Q

What is the importance of the amino acid sequence in the primary structure?

A

Determines the way the polypeptide chain folds
the structure of the protein
and hence its function

27
Q

What are peptides/oligopeptides?

A

Chains of a few amino acids joined together

28
Q

What are polypeptides/proteins?

A

Chains of many amino acids joined together

29
Q

What type of bond is a peptide bond?

A

Covalent bond

30
Q

What is the secondary structure?

A

The spatial arrangement of the polypeptide backbone

31
Q

What are the types of secondary structures?

A

Alpha helix

Beta strand

32
Q

What do layers of beta strands form?

A

Beta pleated sheet

33
Q

What holds the alpha helix and the beta pleated sheets together?

A

Hydrogen bonds between C=O and N-H

34
Q

What are the types of beta sheets? What do they each mean?

A

Parallel - run in same direction

Anti parallel - run in opposite directions

35
Q

How does the polypeptide chain fold up into an alpha helix or beta pleated sheet if peptide bonds are rigid?

A

Bonds next to peptide bonds are free to rotate

36
Q

What is the tertiary structure?

A

Secondary structure folds up to form a 3D conformation

37
Q

What are the types of tertiary structures? What do they each mean?

A

Globular - spherical shape

Fibrous - long strand-like shape

38
Q

What is the general function of fibrous proteins?

A

Structural support

Maintain shape

39
Q

How many types of secondary structures are there in fibrous proteins?

A

Single repeating secondary structure

40
Q

How many types of secondary structures are there in globular proteins?

A

Several different types

41
Q

What is a classic example of a fibrous protein?

A

Collagen

42
Q

What is a protein domain?

A

Part of polypeptide chain that folds into a distinct shape

has a specific function

43
Q

How do water-soluble proteins generally fold up?

A

Non-polar hydrophobic side chains are buried within

Polar/charged hydrophilic side chains are on surface

44
Q

How do integral membrane proteins generally fold up? Why?

A

Non-polar hydrophobic chains are on the surface
interact with hydrophobic tails

Polar/charged hydrophilic chains form a channel within
interact with water in and out of cell

45
Q

What is the quarternary structure?

A

Different polypeptide chains coming together to form a multi-subunit protein

46
Q

What is an example of a protein with a quarternary structure?

A

Hb

47
Q

What is an example of a protein with a tertiary structure?

A

Myoglobin

48
Q

What does pI stand for?

A

Isoelectric point

49
Q

What is the pI of proteins?

A

pH at which protein has no overall charge

50
Q

Do acidic proteins have a low or high pI value? Why?

A

Low

low pH means more hydrogen ions, neutralises negative charge of acidic amino acid

51
Q

Do basic proteins have a low or high pI value? Why?

A

High

high pH means fewer hydrogen ions, because already have positively charged amino acids

52
Q

What happens to the protein if pH > pI? Why?

A

High pH means fewer hydrogen ions
amino acid gives up hydrogen ions
becomes deprotonated

53
Q

What happens to the protein if pH < pI? Why?

A

Low pH means more hydrogen ions
amino acid takes up hydrogen ions
becomes protonated

54
Q

What are conjugated proteins?

A

Proteins covalently linked to additional chemical components that are not amino acids

55
Q

What are some examples of roles of proteins? Give examples for some roles

A

Structural support e.g. collagen

Enzymes e.g. hexokinase

Transporters e.g. Hb

Carriers, channels etc.

Receptors, ligands etc.

Cell Biology and Genetics (32 decks)

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