Proteins and Amino Acids Flashcards
What are the components of an amino acid?
Amino group
Acidic carboxyl group
Hydrogen atom
R group
Name the essential amino acids.
M - methionine
V - valine
W - tryptophan
F - phenylalanine
I - isoleucine
K - lysine
T - threonine
L -leucine
H - histidine
How is the amino group found in amino acids?
Protonated to NH3+
How is the carboxyl group found at physiological pH?
COO-
What is the carbon next to the carboxyl group called?
Alpha carbon
Chiral centre
How many stereoisomers can a molecule with a single chiral carbon have?
2
What is an enatiomer?
Stereoisomers which are mirror images of each other but cannot be superimposed on each other
What form are human amino acids found in?
L form
Where are D form amino acids found?
Peptides of bacterial cell walls and antibiotics
What amino acids have non-polar, aliphatic R groups?
G - Glycine
L - Leucine
I - Isoleucine
V - Valine
M - Methionine
A - Alanine
P - Proline
Which amino acid is actually an imino acid?
Proline
What does proline’s structure mean for its funciton?
Rigid structure means that it reduces flexibility of polypeptides that contain it e.g. collagen
What amino acids have aromatic R groups?
W - tryptophan
F - phenylalanine
Y - Tyrosine
Which amino acids with aromatic R groups are more polar?
Tyrosine - due to its OH group
Tryptophan - due to its N indole ring
What unique ability do tyrosine and tryptophan have?
Can absorb UV light
What amino acids have polar, uncharged R groups?
C - cysteine
Q - Glutamine
N - Asparagine
T - threonine
S - Serine
What may happen to serine and threonine?
Phosphorylated at their OH group
Oligosaccharide group attached to their oxygen atom - O-glycosylation
What may happen to asparagine?
Oligosaccharide group attached to its amide group - N-glycosylation
What is unique about cysteine?
Sulfhydryl group gives it to ability to form strongly hydrophobic disulphide bonds
What amino acids have positively charged R groups?
H - histidine
R - Arginine
K - Lysine
Which amino acid is weakly basic and why?
Histidine due to the imidazole ring
What amino acids have negatively charged R groups?
E - Glutamate
D - Aspartate
Name an amino acid that exists as a free molecule.
Creatine
What is the name of the bonds that link amino acids together?
Peptide bonds
