MGD LECTURE 1.1 AMINO ACIDS AND PROTEINS Flashcards
What is the basic structure of an amino acid?
Chiral Carbon surrounded by hydrogen, carboxyl group, amino group and an R group. Exists only in L form.
What state is an amino acid in at a pH of 7.4?
Zwitterion
What does the solubility of an amino acid depend on?
The ability of its R group to form hydrogen bonds
Name two types of hydrophobic amino acids
Non Polar aliphatic (non ringed) and Aromatic (benzene ring in R group)
Name three types of hydrophillic amino acids
Positively charged R groups, Negatively charged R groups and polar (hydrogen bonded) R groups
What is an ampiphatic amino acid?
An amino acid which displays both polar and non polar qualities - hydrophobic and hydrophillic to equal extents
what is a micelle?
Hydrophobic groups on inside, hydrophillic on outside. Result of ampiphatic amino acids
What is a PK value?
A measure of PH
What happens if PH is less than PK value of amino acid?
Amino acid will be protonated
What is the general PKr for positively charged amino acids?
6.0 - 12.5
PKr for negatively charged?
0-6.0
Name 7 roles of proteins and give examples. Bitch.
Receptors (for hormones, neurotransmitters) Immune protection (immuno globins) Transporters (haemoglobin) Machines (muscular contraction) Catalysts (enzymes) Structure (collagens) Ion channels
How does a peptide bond form?
via the abstraction of a water molecule from two adjacent amino acids
Why is the peptide bond rigid?
Because C-N has partial double bond characteristics, so is rigid and planar.
What sterisomeric form do peptide bonds exist in organically?
Trans, Cis causes steric clash (repulsion)
What is a peptide?
A few amino acids joined together
What is a conjugated protein?
Proteins which contain covalently linked chemical components, such a haem or lipoproteins.
What is the isoelectric point?
The point at which there is no charge on a protein
What is the definition of a basic protein?
Protein with PI >7 and many positively charged R groups on amino acids
What is the definition of an acidic protein?
PI <7, contains many negatively charged R groups
What are 2 key features of a protein?
Made up of many different aa
Amino acid sequence encoded by a gene
