Top3-Ch3-P71-77Reverse

Question 23

1. nucleic acids (DNA)
2. proteins
3. polysaccharides

Answer 23

1. Nucleotides are subunits of ?
2. amino acids are subunits of ?
3. monosaccharides are subunits of ?

Question 24

protein

1. Glutamate and glycine neurotransmitters
2. Parkinson’s disease due to reduced dopamine. Dopamine synthesised from tyrosine.
3. Derivatives of AAs eg. Histamine, derived from histidine implicated diseases such as asthma.

Answer 24

Amino acids are the monomers for _____ polymers

BUT Also……AA’s have specialised functions. Name three of them and explain a bit.

Question 25

All amino acids have:

• the same skeleton of a central (or alpha) carbon atom, with attachments of:
  
  • an amino group;
  • a carboxy group;
  • a hydrogen atom; and
• an R side-chain group.

Answer 25

Describe basic structure of amino acid

Question 26

20

Answer 26

How many different amino acids are there

Question 27

As R varies with all the amino acids, the α carbon will be asymmetric or chiral (nonsuperimposable mirror image) in all cases but one. This exception is glycine, where the R group is H. This means that all amino acids except for glycine are optically active and hence there are two
isomers.

Optical rotation (optical activity) is the turning of the plane of linearly polarized light about the direction of motion as the light travels through certain materials. It occurs in solutions of chiral molecules such as sucrose (sugar), solids with rotated crystal planes such as quartz, and spin-polarized gases of atoms or molecules.

any crystal or molecule that can’t be superimposed on its mirror image will be optically active

Answer 27

Explain optical activity in relation to amino acids.

Question 28

L-isomers

left side.

That means the D is on the right side.

Answer 28

all amino acids found in natural proteins in most
animals are L or D -isomers? Because of this we write the structures with the amino groups on the left or right side?

Question 29

Answer 29

Amino acid nomenclature diagram

Question 30

chiral

Answer 30

In the structure of amino acids the α-carbon atom has a ‘____ centre’

Question 31

rotate polarized light

Answer 31

optically active means it can

Question 32

L

synthesise L

NOTE: glycine is the exception, does not have a chiral carbon. Is NOT optically active

Answer 32

amino acids have L and D forms
BUT:
almost all AA in proteins are __ stereoisomers
cells specifically _____ _ stereoisomers.

The exception is?

Question 33

• Numbering of C starts at carboxyl carbon
• Based upon similarity of configuration to L- and D-glyceraldehyde
• Cells specifically form L- isomer, as active site of enzymes are asymmetric

Answer 33

See diagram of L v D configuration and explanation

Question 34

As you can see amino group is on left for L-AAs

Answer 34

Describe Alanine the simplest chiral amino acid

Question 35

No chiral centre and chiral centre means that all the 4 off Carbon must be different and chiral centre is easiest way to identify chiral compound

Answer 35

Describe Glycine. Is it chiral or not?

Question 36

1. non-polar, aliphatic (Non polar and hydrophobic)
2. aromatic (relatively nonpolar - hydrophobic - All can participate in hydrophobic interactions.
3. polar, uncharged (more soluble in water, more hydrophilic.)
4. positively charged (basic) - ( most hydrophilic groups are those either positively or negatively charged)
5. negatively charged (acidic) - ( most hydrophilic groups are those either positively or negatively charged)

Answer 36

Amino acids are classified by their R-group. Name the five groups

Question 37

Answer 37

Nonpolar, aliphatic R groups, name them and give formulaes

Question 38

• Relatively non-polar,
• hydrophobic interactions
• Some H-bonding

Answer 38

Aromatic R groups, name and formula and give some rules.

Question 39

Answer 39

Aromatic electron cloud, see picture

Question 40

UV light

Answer 40

Aromatic Amino Acids absorbs

Question 41

• Hydrophilic,
• H bonds
• Polarity-
  
  • serine, threonine
    
    • -OH group
  • Cysteine:
    
    • sulfhydryl group
    • weak acid. pKa 8.2
    • weak H bonding
  • Asparagine + glutamine
    
    • amide group

Answer 41

Polar, uncharged R Group, name, give group descriptions.

Question 42

• Often found at hydrophilic
• Enzyme active sites
• Note similarity to Asparagine & Glutamine from the polar, uncharged group

Answer 42

Negatively charged (acidic) R Groups, name, describe.

Question 43

• Cysteine thiol group is nucleophilic and easily oxidised to Cystine (reversible)
• Both are hydrophobic residues
• Important role in stabilising protein structures by cross linking polypeptides

Answer 43

Explain formation of Disulfide bond

Question 44

Answer 44

Positively charged (Basic) R Groups, name

Question 45

Answer 45

Learn groups and amino acids and symbols see attached