Proteins Flashcards
What 2 functional groups does an amino acid have?
an amino group (NH2)
a carboxylic acid group (COOH)
What forms do proteins consist of only?
L forms (left)
Give an example of an amino acid with an acidc R group.
Aspartic acid
Give an example of a basic amino acid.
arginine
Give an example of an uncharged polar amino acid.
glutamine
Give an example of a polar amino acid.
glycine, alanine
How is a peptide bond formed?
condensation reaction
What is meant by the ‘primary structure’ of a protein?
the sequence of amino acids
How many different types of amino acid are there?
20
What is meant by the ‘secondary structure’ of an amino acid?
spatial arrangement of amino acid residues that are near each other in the linear sequence
What are the 2 forms the secondary structure can take?
alpha helix
beta pleated sheets
How is the shape of the alpha helix maintained?
by hydrogen bonds between C=O group and N-H group
What is meant by the ‘tertiary structure’ of a protein?
the spatial arrangement of amino acid residues that are FAR APART in a linear sequence
What are the 5 ways that the tertiary structure is maintained? (Bonding)
- van der waals
- hydrogen bonding
- ionic interactions
- disulphide bridges (between cysteine residues)
- hydrophobic interactions
What is meant by the ‘quaternary structure’ of a protein?
the spatial arrangement of individual polypeptide chains in a multi-subunit protein
What is an example of a complex with a quaternary structure?
haemoglobin
What structures of protein are affected by denaturation?
secondary and tertiary
Why is primary structure of protein not affected by denaturation?
the reactions aren’t strong enough to break the peptide bonds
Give 2 examples of causes of denaturation of proteins.
acids
heat
What are some examples of the effects of denaturation? (4)
- decreased solubility
- altered water binding capacity
- loss of biological activity
- improved digestibility
What do peptidases do?
cleave peptide bonds
What do endopeptidases do?
cleave internal bonds of protein
What do exopeptidase do?
cleave away one amino acid at a time
What do carboxypeptidases do?
cleave at COOH terminal
What do amino peptidases do?
cleave at NH2 terminal
