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Flashcards in Amino Acids. Deck (88):
1

How many amino acids are there in nature?

Over 300.

2

How many amino acids are coded for by DNA?

20.

3

What is an essential amino acid?

An amino acid that is needed by the body but cannot be made by the body.

Therefore essential amino acids must be taken in via the diet.

4

Amino acids are the building blocks for what macromolecule?

Proteins.

5

Proteins can vary in what 2 aspects?

In structure and function.

6

What ultimately determines the structure and function of a protein?

Its amino acid composition.

7

What are 3 common functions that proteins can function as?

Cell surface receptors.

Hormones.

Enzymes.

8

Proteins are used as structural components for what body parts?

Cell membranes.

Organelles.

Muscle.

Bone.

Skin.

9

What are 2 specialised proteins that perform specific roles in the body?

Haemoglobin.

Immunoglobin.

10

What end is the amino end of an amino acid?

NH3+.

11

What is the carboxylic end of an amino acid?

COO-.

12

What is the alpha carbon on the amino acid?

The alpha carbo is the carbon that is bound to the amino group and the carboxylic group.

It is also bound to a hydrogen atom and an R group.

13

What is an R group on an amino acid?

The R group is a unique chain that is bound to the alpha carbo.

14

What gives an amino acid its unique properties?

The R group.

15

Amino acids are classified by what?

Their R groups.

16

What structure is common to all amino acids?

The alpha carbon that is bound to a hydrogen atom, an amino group, an R group and a carboxylic acid.

17

What dictates whether an amino acid will gain or lose a proton from its carboxyl or amino groups?

The pH of the solution that the amino acid is in.

18

What type of bond can join 2 amino acids together?

A peptide bond.

19

What is a peptide bond?

When the carboxylic end of one amino acid can bond to the amino end of another amino acid.

20

How are peptide bonds formed?

OH is removed from the carboxyl end of 1 amino acid and H is removed from the amino end of another amino acid.

This allows the carboxylic carbon to bind to the amino N, joining the 2 molecules together.

The H and the OH that were lost will form H2O.

21

What type of reaction leads to the formation of a peptide bond?

A dehydration reaction.

22

What is a polypeptide?

A long chain of amino acids that are joined together by peptide bonds.

23

How many carboxyl and amino groups are in a chain of amino acids?

There will be 1 amino end and one carboxyl end at the terminal end of the amino acid.

24

In a polypeptide, what are the exposed functional groups?

The R groups.

The terminal amino group.

The terminal carboxyl group.

25

What is a zwitterionic form of an amino acid?

An amino acid where the carboxyl end has a negative charge and the amino end has a positive charge giving a net charge of 0.

26

What is the net charge of a zwitterionic amino acid?

0.

27

What is physiological pH?

7.5.

28

What form do all amino acids exist in at physiological pH?

The Zwitterionic form.

29

What atoms are the R groups of non polar amino acids likely to contain?

Carbon and hydrogen atoms.

30

Do the R groups of non polar amino acids have a charge?

No.

The R groups of non polar amino acids are uncharged.

31

Do the R groups of non polar amino acids release a proton or dissociate?

No.

32

Do any of the atoms on the R groups of non polar amino acids form hydrogen bonds?

No.

33

Are the R groups of non polar amino acids hydrophobic or hydrophilic?

Hydrophobic.

34

Is there any part of a non polar amino acid that can give off protons or dissociate?

Yes.

The amino or carboxyl groups on an amino acid can always dissociate.

35

Are non polar R groups involved in many reactions?

No.

36

What is the smallest amino acid?

Glycine.

37

What is the R group of glycine?

1 hydrogen atom.

38

What is a chiral carbon?

A carbon that is bound to 4 different atoms.

39

Are all amino acids chiral?

All except glycine.

40

Why is glycine achiral?

Because it is bound to 2 identical hydrogen atoms.

41

What is the R group on alanine?

A methyl group (CH3).

42

What is the R group on valine?

An isopropyl group.

A CH is bound to the a carbon and to 2 methyl groups.

43

What is the R group on leucine?

It is the same as valine except it is an isobutyl group.

There is a CH2 bound to a CH which is bound to 2 methyl groups.

44

What is the R group on isoleucine?

It consists of a 3 carbon chain.

The carbon that is bound to the amino acid is the 1st in the chain, it is bound to a CH3 and a H.

The other 2 groups in the chain are CH3s.

45

What are the branched chain amino acids?

Valine.

Isoleucine.

Leucine.

46

What is the only non polar amino acid with an aromatic ring?

Phenylalanine.

47

What is the R group of phenylalanine?

A CH2 bound to a phenyl group.

48

Why is the R group of tryptophan unique?

Because it is the only R group that has 2 rings.

49

Tryptophan is one of 2 non polar amino acids to contain what atom in its R chain?

Nitrogen.

50

Is the body able to make methionine?

No.

Methionine is an essential amino acid.

51

Methionine is the only non polar amino acid to contain what atom in its R chain?

Sulphur.

52

Why is methionine non polar even though it contains a sulphur atom?

The adjacent methyl group shields the sulphur group and keeps methionine non polar.

53

Why does proline have a unique R group?

Because the R group is bound to the amino group.

54

What type of amino group is on proline?

An imino group.

55

Describe the R group of proline.

a Carbon-CH2-CH2-CH2-imino group.

56

What is the difference between an amino group and an imino group?

An amino group is primary as it is bound to 2 hydrogens.

An imino group is secondary as it is bound to the a carbon and the R group.

57

In soluble proteins, where are the non polar amino acids usually found?

On the interior of the protein.

58

Why are non polar amino acids usually found on the interior of soluble proteins?

So they can be shielded from an aqueous environment.

59

Why do non polar amino acids in soluble proteins need to be shielded from an aqueous environment?

Because they are hydrophobic.

60

What kind of amino acids make up the exterior of soluble proteins?

Polar amino acids.

61

Why do polar amino acids make up the exterior of soluble proteins?

Because they can interact with water by forming H bonds allowing the protein to be soluble.

62

Are polar amino acids hydrophobic or hydrophilic?

Hydrophilic.

63

What kind of amino acids will be on the surface of membrane proteins?

Non polar amino acids.

64

What kind of amino acids will be on the surface of proteins in hydrophobic environments?

Non polar amino acids.

65

Why are non polar amino acids found on the interior of membrane proteins?

Because the interiors of cell membranes contain many fatty acid tails which are non polar.

This allows for non polar amino acids to interact with non polar fatty acid tails.

66

The type of amino acids that make up a protein can dictate what about the protein?

How the protein interacts with its environment,

67

What are the non polar amino acids?

GAV The Lazy PIMP.

Glycine. (Gly.)

Alanine. (Ala.)

Valine. (Val.)

Tryptophan. (Trp.)

Leucine. (Leu.)

Phenylalanine. (Phe.)

Isoleucine. (Ile.)

Methionine. (Met.)

Proline. (Pro.)

68

What is the 3 letter abbreviation for glycine?

Gly.

69

What is the 3 letter abbreviation for alanine?

Ala.

70

What is the 3 letter abbreviation for valine?

Val.

71

What is the 3 letter abbreviation for tryptophan?

Trp.

72

What is the 3 letter abbreviation for leucine?

Leu.

73

What is the 3 letter abbreviation for phenylalanine?

Phe.

74

What is the 3 letter abbreviation for isoleucine?

Ile.

75

What is the 3 letter abbreviation for methionine?

Met.

76

What is the 3 letter abbreviation for proline?

Pro.

77

What are the branched amino acids?

LIV.

Leucine.

Isoleucine.

Valine.

78

Molecules with chiral centres can take up how many orientations in 3D space?

2.

79

The 2 arrangements that molecules with chiral centres can take up in 3D space are called what?

Stereoisomers or enantiomers.

80

How do stereoisomers differ from the original molecule?

A stereoisomer is a superimposable mirror image of the original molecule.

81

Which amino acid is the only amino acid to not have a stereoisomer?

Glycine.

82

What are the 2 forms of stereoisomer that amino acids can take?

A D and an L form.

83

Which enantiomer of amino acids is used by the body

The L form.

84

Is the D form of amino acids used by the body?

No.

85

What are stereoisomers?

These are molecules which have the same chemical formula yet different structural arrangements.

E.g. Cis and trans isomers.

86

What are optical isomers of amino acids?

This is when the atoms of the amino acid are arranged vertically with the alpha carbon below the carboxyl group and then the R chain is below the alpha carbon.

This means the amino group is either to the right or left of the alpha carbon.

87

Describe a D isomer of an amino acid?

This is an optical isomer of the amino acid when the amino group is to the right of the alpha carbon.

88

Describe an L isomer of an amino acid?

This is an optical isomer of the amino acid when the amino group is to the left of the alpha carbon.