protein Flashcards
general structure of an amino acid
carboxylic group ,hydrogen group , variant group and amino group
how are poly peptides formed
condensation reaction between 2 +amino acids form peptide bonds
what is the primary structure of a protein
sequence, number type of amino acids in the polypeptide determined by the sequence of codons on MRNA
what is the secondary structure of protein
alpha helix and beta pleated sheet
2 types of secondary structure
alpha helix
beta pleated sheet
what is the alpha helix
spiral shape
hydrogen bonds parallel to helical axis
all nitrogen-hydrogen bonds on same side of protein chain
what is the beta pleated sheet
nitrogen-hydrogen and C=O groups alternate from one side to the other
what is the tertiary structure of protein
disulphide bridges ionic bonds hydrogen bonds
what are disulphide bridges
strong covalent S-S bonds between cystine and amino acid
what are the ionic bonds for in tertiary structure
strong bonds between charged r groups
what are hydrogen bonds for in tertiary structure
they Are easily broken
what is the quaternary structure of a protein
may consist of more than 1 polypeptide
3d structure held together by the same bonds as tertiary
involves addition of prosthetic groups
describe the structure of globular proteins
spherical and compact
hydrophilic r groups face outward
hydrophobic r groups point inward
soluble
involved in metabolic processes eg enzymes like amylase and insulin
usually for function
describe structure of haemoglobin
globular conjugcated protein with prosthetic group
2 alpha chains 2 beta chains 4 haem groups
water soluble so dissolves in plasma
tertiary structure changes so its easier for oxygen molecules to bind
describe the structure of fibrous proteins
form long chains or fibres
insoluble in water
useful for structure and support
eg collagen in skin
