protein structure Flashcards
draw the structure of an amino acid
from flashcard
what are the 4 different groups on an amino acid ?
- amine group
- carboxyl group
- hydrogen group
- variable group
how many options are there for the R group ?
20
what kind of bond is formed between 2 amino acids during a condensation reaction ?
a peptide bond
Draw how 2 amino acids are joined together
from notes
what is a protein ?
proteins are polymers, made up of the monomer : amino acids
how many different amino acids are there ?
20
how is a polypeptide chain created ?
when more amino acids are added to a dipeptide
what is the molecule called when a peptide forms between 2 amino acids ?
the molecule is called a dipeptide
what are the different levels of structure in a protein ?
- primary structure
- secondary
- tertiary
- quaternary
what is meant by the primary structure of a protein ?
it is the order / sequence of amino acids in the polypeptide chain
what is meant by the secondary structure of a protein ?
when the sequence of amino acids causes parts of a protein molecule to bend into an alpha helix shape or a beta pleated sheet.
draw the structure of an alpha helix shape
notes
draw the structure of a beta pleated sheet
notes
how are the structures of the secondary protein held together ?
hydrogen bonds hold the secondary structures shape
where do the hydrogen bonds form in the secondary structures ?
hydrogen bonds form between the C=O groups of the carboxyl group of one amino acid and the H in the amine group of another amino acid
what is the tertiary structure of a protein ?
- the further folding of the secondary structure
- to form a unique 3D shape
- held in place by ionic, hydrogen and disulfide bonds
where do the ionic and disulfide bonds form ?
they form between the R groups of different amino acids
when do disulfide bonds occur ? and why ?
they only occur sometimes
because there must be a sulfur in the R group for the bond to occur
where do hydrogen bonds form in a protein ?
hydrogen bonds form between all levels of the structure
where do hydrophobic interactions occur in a protein ?
they occur between non-polar sections of the protein
where do disulfide bonds occur in a protein ?
they occur between 2 cysteine amino acids
name the bonds in the tertiary structure in order of weakest to strongest ?
hydrogen bonds
ionic bonds
disulfide bonds
state the molecular formula of cysteine
CH2SH
what is meant by the quaternary structure of a protein ?
a protein made up of more than 1 polypeptide chain
what is an example of a quaternary structure of a protein ?
haemoglobin
- it has 4 polypeptides
what happens to the bonds if the protein is denatured ?
it means that the bonds which hold the tertiary and secondary structure (ionic and hydrogen bonds break ) in shape break and therefore the unique 3D shape is lost
what are conditions that may denature a protein ?
- too high temperature
- too high/too low pH (too many H+ or OH-)
state the importance of the primary structure.
and what impact will that have on an enzyme ?
if even one amino acid in the sequence is different it will cause the ionic/hydrogen/disulfide bonds to form in a different location
which will result in a different 3D shape
so in enzymes, they will have a different shaped active site and so will be non-functioning
specific function is due to what ?
specific function is due to the specific shape
what can a functional protein contain ?
it may contain one or more polypeptides
