Amino Acids.

Question 1

How many amino acids are there in nature?

Answer 1

Over 300.

Question 2

How many amino acids are coded for by DNA?

Answer 2

20.

Question 3

What is an essential amino acid?

Answer 3

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.

Question 4

Amino acids are the building blocks for what macromolecule?

Answer 4

Proteins.

Question 5

Proteins can vary in what 2 aspects?

Answer 5

In structure and function.

Question 6

What ultimately determines the structure and function of a protein?

Answer 6

Its amino acid composition.

Question 7

What are 3 common functions that proteins can function as?

Answer 7

Cell surface receptors.

Hormones.

Enzymes.

Question 8

Proteins are used as structural components for what body parts?

Answer 8

Cell membranes.

Organelles.

Muscle.

Bone.

Skin.

Question 9

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

Answer 9

Haemoglobin.

Immunoglobin.

Question 10

What end is the amino end of an amino acid?

Answer 10

NH3+.

Question 11

What is the carboxylic end of an amino acid?

Answer 11

COO-.

Question 12

What is the alpha carbon on the amino acid?

Answer 12

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.

Question 13

What is an R group on an amino acid?

Answer 13

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

Question 14

What gives an amino acid its unique properties?

Answer 14

The R group.

Question 15

Amino acids are classified by what?

Answer 15

Their R groups.

Question 16

What structure is common to all amino acids?

Answer 16

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

Question 17

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

Answer 17

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

Question 18

What type of bond can join 2 amino acids together?

Answer 18

A peptide bond.

Question 19

What is a peptide bond?

Answer 19

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

Question 20

How are peptide bonds formed?

Answer 20

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.

Question 21

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

Answer 21

A dehydration reaction.

Question 22

What is a polypeptide?

Answer 22

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

Question 23

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

Answer 23

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

Question 24

In a polypeptide, what are the exposed functional groups?

Answer 24

The R groups.

The terminal amino group.

The terminal carboxyl group.

Question 25

What is a zwitterionic form of an amino acid?

Answer 25

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.

Question 26

What is the net charge of a zwitterionic amino acid?

Answer 26

0.

Question 27

What is physiological pH?

Answer 27

7.5.

Question 28

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

Answer 28

The Zwitterionic form.

Question 29

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

Answer 29

Carbon and hydrogen atoms.

Question 30

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

Answer 30

No. The R groups of non polar amino acids are uncharged.

Question 31

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

Answer 31

No.

Question 32

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

Answer 32

No.

Question 33

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

Answer 33

Hydrophobic.

Question 34

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

Answer 34

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

Question 35

Are non polar R groups involved in many reactions?

Answer 35

No.

Question 36

What is the smallest amino acid?

Answer 36

Glycine.

Question 37

What is the R group of glycine?

Answer 37

1 hydrogen atom.

Question 38

What is a chiral carbon?

Answer 38

A carbon that is bound to 4 different atoms.

Question 39

Are all amino acids chiral?

Answer 39

All except glycine.

Question 40

Why is glycine achiral?

Answer 40

Because it is bound to 2 identical hydrogen atoms.

Question 41

What is the R group on alanine?

Answer 41

A methyl group (CH3).

Question 42

What is the R group on valine?

Answer 42

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

Question 43

What is the R group on leucine?

Answer 43

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.

Question 44

What is the R group on isoleucine?

Answer 44

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.

Question 45

What are the branched chain amino acids?

Answer 45

Valine. Isoleucine. Leucine.

Question 46

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

Answer 46

Phenylalanine.

Question 47

What is the R group of phenylalanine?

Answer 47

A CH2 bound to a phenyl group.

Question 48

Why is the R group of tryptophan unique?

Answer 48

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

Question 49

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

Answer 49

Nitrogen.

Question 50

Is the body able to make methionine?

Answer 50

No. Methionine is an essential amino acid.

Question 51

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

Answer 51

Sulphur.

Question 52

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

Answer 52

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

Question 53

Why does proline have a unique R group?

Answer 53

Because the R group is bound to the amino group.

Question 54

What type of amino group is on proline?

Answer 54

An imino group.

Question 55

Describe the R group of proline.

Answer 55

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

Question 56

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

Answer 56

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.

Question 57

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

Answer 57

On the interior of the protein.

Question 58

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

Answer 58

So they can be shielded from an aqueous environment.

Question 59

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

Answer 59

Because they are hydrophobic.

Question 60

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

Answer 60

Polar amino acids.

Question 61

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

Answer 61

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

Question 62

Are polar amino acids hydrophobic or hydrophilic?

Answer 62

Hydrophilic.

Question 63

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

Answer 63

Non polar amino acids.

Question 64

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

Answer 64

Non polar amino acids.

Question 65

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

Answer 65

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.

Question 66

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

Answer 66

How the protein interacts with its environment,

Question 67

What are the non polar amino acids?

Answer 67

GAV The Lazy PIMP. Glycine. (Gly.) Alanine. (Ala.) Valine. (Val.) Tryptophan. (Trp.) Leucine. (Leu.) Phenylalanine. (Phe.) Isoleucine. (Ile.) Methionine. (Met.) Proline. (Pro.)

Question 68

What is the 3 letter abbreviation for glycine?

Answer 68

Gly.

Question 69

What is the 3 letter abbreviation for alanine?

Answer 69

Ala.

Question 70

What is the 3 letter abbreviation for valine?

Answer 70

Val.

Question 71

What is the 3 letter abbreviation for tryptophan?

Answer 71

Trp.

Question 72

What is the 3 letter abbreviation for leucine?

Answer 72

Leu.

Question 73

What is the 3 letter abbreviation for phenylalanine?

Answer 73

Phe.

Question 74

What is the 3 letter abbreviation for isoleucine?

Answer 74

Ile.

Question 75

What is the 3 letter abbreviation for methionine?

Answer 75

Met.

Question 76

What is the 3 letter abbreviation for proline?

Answer 76

Pro.

Question 77

What are the branched amino acids?

Answer 77

LIV. Leucine. Isoleucine. Valine.

Question 78

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

Answer 78

2.

Question 79

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

Answer 79

Stereoisomers or enantiomers.

Question 80

How do stereoisomers differ from the original molecule?

Answer 80

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

Question 81

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

Answer 81

Glycine.

Question 82

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

Answer 82

A D and an L form.

Question 83

Which enantiomer of amino acids is used by the body

Answer 83

The L form.

Question 84

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

Answer 84

No.

Question 85

What are stereoisomers?

Answer 85

These are molecules which have the same chemical formula yet different structural arrangements. E.g. Cis and trans isomers.

Question 86

What are optical isomers of amino acids?

Answer 86

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.

Question 87

Describe a D isomer of an amino acid?

Answer 87

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

Question 88

Describe an L isomer of an amino acid?

Answer 88

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