proteins Flashcards
what are the monomers of proteins
amino acids
how is a dipeptide formed
when two amino acids join together
how is a polypeptide formed
when more than two amino acids join together
what are proteins made up of
one or more polypeptides
what is the amino acid structure
a carboxyl group (COOH)
and amino group (NH2)
and an R group
what is the R group known as
the variable side group
how are amino acids linked together
condensation reactions
what are the bonds that are formed between amino acids called
peptide bonds
how many structures are there
4
describe the primary structure
sequence of amino acids in the polypeptide chain
describe the secondary structure
hydrogen bonds form between the amino acids in the chain and this causes the chain to coil into and alpha helix and folded into a beta pleated sheet
describe the tertiary structure
the amino acids are coiled and folded further. more bonds are made including hydrogen bonds, ionic bonds and disulfide bridges. For proteins made with a single polypeptide chain this is their final 3D structure
what are the three bonds made in tertiary structure of a protein
ionic bonds, hydrogen bonds and disulfide bridges
is the tertiary structure a final structure
yes for proteins made from one polypeptide chain
describe the quaternary structure
several polypeptide chains held together by bonds final 3D structure
give an example of a protein made from more than one polypeptide chain
haemoglobin, insulin, collagen
what does a proteins shape do
it determines its function
why is haemoglobin good
it is a compact, soluble protein which makes it easy to transport. This makes it great for carrying oxygen around the body
why are enzymes good
roughly spherical in shape due to the tight folding of the polypeptide chains, they’re soluble and often have roles in metabolism
what is the test for proteins
the biuret test
how do you carry out the test for proteins
add a few drops of sodium hydroxide solution to the test as it needs to be alkaline. then you add copper sulphate
what is the positive result of the biuret test
the solution will turn purple
what is a negative result of the biuret test
the solution will stay blue
