Biology - 1.4.1 - general properties of proteins
what is an amino acid?
monomers from which proteins are made
where is the amine group in an amino acid?
the left side
where is the carboxyl group in an amino acid?
the right side
where is the R group in an amino acid?
the middle top
what does the R group in an amino acid determine?
determines the type of amino acid out of the 20 possible ones
how is a peptide bond formed?
a condensation reaction between two amino acids
how is a dipeptide formed?
condensation between 2 amino acids
how is a polypeptide formed?
condensation between many amino acids
what is the primary level of structure in a protein?
a sequence of amino acids bonded by peptide bonds as a result of condensation reaction
how does primary structure affect the other structures
the number and order of amino acids affects other structures
what is the secondary level of structure in a protein?
coiling or folding of amino acid chain to result in an alpha helix or a beta pleated sheat
how do hydrogen bonds occur in a secondary structure
between the NH2 group and carboxyl groups
what is the tertiary level of structure in a protein?
combination of pleated sheets and helixes, now a polypeptide which is 3D in shape
how are tertiary structures held together
hydrogen, ionic, and disulfide bonds
hydrophilic and phobic interactions to face R group inwards
why does the R group face inward in a tertiary structure
they are hydrophobic
how does heat affect tertiary structures
denatured by heat as kinetic energy loosens the shape and returns to the primary structure
what is the quaternary level of structure?
consists of more than 1 polypeptide chain (multiple tertiary)
what is an example of a quaternary structure
haemoglobin
how do secondary structures form
weak negatively charged nitrogen and weak positively charged hydrogen attract to eachother forming hydrogen bonds
how does a beta pleated sheet form
protein folds so that 2 parts of the polypeptide chain are parallel to eachother encouraging hydrogen bonds to occur between parallel peptide bonds
how does an alpha helix form
hydrogen bonds form every fourth peptide bonds
how do disulfide bonds form in tertiary structure
interactions between sulfur in R groups
how do ionic bonds form in tertiary structure
from between carboxyl and and amino groups that are not involved in a peptide bond
how do hydrogen bonds form in tertiary structure
numerous between many hydrogens, easily broken