proteins Flashcards
what is a chain of amino acids called
a polypeptide chain
what is the structure of an amino acid
carbon (C) attached to an amine (NH3), a carboxyl (COOH), and an R group (varient)
how many different R groups/amino acids are there
20
what bonds are in a polypeptide
peptide bonds
where do the peptide bonds form
between N in amine group and C in carboxyl group
what type of reaction forms a dipeptide
condensation
what does a condensation reaction produce
H20
what is the primary structure
sequence of amino acids in a polypeptide chain
what can a change in the polypeptide amino sequence cause
may cause a change in the protein shape and may stop it from carrying out its function
what is the secondary structure
either an alpha helix or a beta pleated sheet
how does the secondary structure form
H of the amine group has overall positive charge
O of the carboxyl group has overall negative charge
hydrogen bonds can form between these 2 groups
causes the chain to be twisted into a 3D shape
what bonds form the tertiary structure
hydrogen bonds
ionic bonds
disulphide bridges
where do the tertiary structure bond forms
only between the R groups
what is the relative strength of hydrogen bonds
weak
what is the relative strength of disulphide bridges
very strong
what are the features of ionic bonds (2)
strong and vulnerable to pH
what is the purpose of the 3D tertiary structure
makes each protein distinctive and allows it to recognise and be recognised by other molecules.
what feature defines a protein having a quaternary structure
protein has more than one polypeptide chain