Amino Acids And Proteins

Question 1

Solubility

Answer 1

the ability to interact with water (not just H-bond)

non-polar molecules are insoluble

Question 2

Amphipathic

Answer 2

have polar and non-polar regions

• hydrophobic regions cluster together - forms micelles
• plasma lipid bilayer

Question 3

Proteins

Answer 3

are polypeptides (amino acids covalently joined) 
amino acid sequence is encoded by a gene - influences 3D shape 

Functions: catalysts (biological enzymes), transporters, for structural support, receptors, ligands

Question 4

Amino acids 
NH2 
|
H--C--COOH
|
R

Answer 4

Has a chiral carbon (alpha carbon) which has 4 distinct groups attached - ONLY THE L ISOMER IS FOUND IN NATURE
20 naturally occurring amino acids

Question 5

Hydrophobic (non-polar) uncharged amino acids

Answer 5

Alanine
Valine
Glycine

Question 6

Hydrophilic (polar) amino acids

Answer 6

Serine
Glutamine
Cysteine

Question 7

Hydrophilic (polar) charged amino acids

Answer 7

Glutamate (-ve)
Aspartate (-ve)
Histidine (+ve)
Lysine (+ve)

Question 8

Acid-base amino acid properties

Answer 8

NH2 acts as a base - accepts protons
COOH acts as an acid - donates protons
acid-base behaviour is determined by the R group

Question 9

R group

Answer 9

Large side chains are more difficult to fold - mutations are more likely.
Aliphatic or aromatic.

Question 10

pK values

Answer 10

If pH is

Question 11

Peptide bond 
    H
     |
~C--N~
||
O

Answer 11

Condensation reaction - elimination of water
Trans orientation
Planar
Has double bond characteristics (no rotation, rigid)

Question 12

Isoelectric Point

pI

Answer 12

The pH at which there is no overall next charge on the protein
Basic proteins pI > 7
Acidic proteins pI

Question 13

Prokaryotic Cells

Bacteria

Answer 13

• have no separate nucleus
• contain a cell wall and a plasma membrane
• lack most organelles