2.1.2 proteins Flashcards
what is the monomer of a protein?
amino acid
how many different R groups are there?
20
20 naturally occurring amino acids
what are R groups important in?
forming the bonds in the tertiary structure of the protein
what does a mutation in DNA cause?
changes the amino acid sequence in a polypeptide which will change the R group and affect the folding to the protein
what are 2 amino acids joined together called?
dipeptide
what is the bond between 2 amino acids joined together called?
peptide bond
if four amino acids are joined together in a condensation reaction, how many water molecules are made?
3
what is a polypeptide?
a string of amino acids joined by peptide bonds
what does 1 gene in DNA code for?
1 polypeptide chain
what is the primary structure of the protein?
the sequence of amino acids and the peptide bonds between them
has no shape or function
what is the secondary structure of the protein?
uses the peptide bond to fold over itself
common secondary structures are alpha- helix and beta-pleated sheets
R-groups are not involved in forming the secondary structure
secondary structure has shape but no function
where does the folding of the secondary structure occur?
rough endoplasmic reticulum
structure of alpha helix
hydrogen bonds form between C=O and the N-H groups
long line is the polypeptide backbone
R groups not involved
structure of beta-pleated sheets
hydrogen bonds between C=O and N-H of the peptide bonds in the polypeptide backbone
what is the tertiary structure of a protein?
has shape and function
minimum level of folding required to form a functional protein
uses hydrogen bonds between the peptide groups
uses R-groups
ionic bonds between positively and negatively charged R-groups
disulphide bond form when R-groups with sulfur come close together
what are the bond strengths of the tertiary structure?
hydrogen bonds are the weakest
then ionic
then disulphide bonds
then covalent bonds
what is quarternary structure of the protein?
more than 1 polypeptide chain in tertiary structure
joined together by H/ ionic/ disulphide bonds
what is the shape of a globular protein?
spherical
what is the solubility of a globular protein?
water-soluble as hydrophilic groups are on the outside
where is the binding site of a globular protein?
often buried within the globular protein
what is the role of a globular protein?
functional
enzymes, receptors, hormones, signal proteins
examples of globular proteins
haemoglobin
pepsin
insulin
what is the shape of a fibrous protein?
filamentous/ elongated
what is the solubility of a fibrous protein?
water- insoluble
hydrophobic R-groups are on the outside
