Proteins Flashcards
what is amino acid
monomers from which proteins are made
draw the general structure of amino acids
what does the NH2 represent
amino group
what does the COOH represent
carboxyl group
what does R group represent
variable group ( 20 options of amino acids)
describe how the amino acids are joined together to form a dipeptide
via a condensation recation
results in the release of water
a peptide bond is formed between the OH in carboxyl group and H in amino group
what are proteins
polymers made up of the monomers amino acid
what are the four levels of structure in protein
primary
secondary
tertiary
quaternary
describe the primary structure
the order/sequence of amino acids in a protein
contains the initial sequence of amino acids and so therefore determine the proteins functions in the end
describe the secondary structure
-the shape that the chain of amino acid makes into either
-alpha helix or beta pleated sheet
-hydrogen bonds hold the secondary structure
-hydrogen bonds formed between the C=O groups of the carboxyl group of one amino acid and H in the amino group of the second amino acid.
when is a dipeptide formed
when two amino acids join together via a condensation reaction
when is polypeptide formed
two or more amino acids join together via a condensation reaction
what are proteins made of
one or more polypeptides
when does hydrolysis happen
when the polypeptide and dipeptides are broken down
describe the tertiary structure
-further folding of the secondary structure
-leads to form a unique 3D shape
-held in place by ionic , hydrogen and disulphide bridges
where are the bonds formed in the tertiary structure
-ionic and disulphide bonds form between the R groups of different amino acids
-Disulphide bonds only sometimes occur as there must be a sulfur in the R groups for this bond to occur (e.g, S—S)
compare and contrast the bonding in the secondary and tertiary structures of a protein(2)
both secondary and tertiary contains hydrogen bonds whilst tertiary further contains ionic and disulphide bridges
explain why the tertiary structure of proteins is important for metabolic reactions (3)
-enzymes are proteins that catalyse biological reactions
-the tertiary structure affects the shape of the enzymes active site
the active site must be complementary to the shape of the substrate in order to catalyse the reaction.
define the quaternary structure
(protein made up of more than one polpeptide chain held together by bonds )
example of a quaternary structure
haemoglobin
Haemoglobin is the oxygen-carrying molecule in red blood cells. At low pH, haemoglobin’s ability to bind to oxygen is reduced.
Suggest why a low pH affects haemoglobin in this way.
interfers with the bonds in the haemoglobin causing it to change shape
means it can no longer bind onto the oxygen
describe the importance of the primary structure and its impact
if one amino acid in the sequence is different then it will cause the ionic, hydrogen / disulphide bonds to form in a diff location
Impact:
-Enzymes will have a different active site shape ( non functioning)
-carrier proteins will have a diff shaped binding site ( so molecules are no longer complementary + so cannot be transported across membranes
