proteins

Proteins are made of.. and are made by…

c, h, o, n, sometimes s, monomer amino acids, made by ribosomes and RER

What're some examples of proteins?

hormones, enzymes, collagen, keratin

Some proteins are… others are…

structural, functional

Structural proteins are…
some examples are…

fibrous, keratin, collagen

Functional proteins are…
some examples are…

globular, enzymes, hormones, antibodies

Fibrous proteins form…

long, insoluble strands

Globular proteins are…

spherical, soluble

Amino acid structure:

central c atom, amino group (base), carboxyl group (acid) and r group

The R group is..

different in each amino acid

Dipeptide:

condensation joins amino acids together, forming peptide bond

Amino acids -> proteins:
Primary protein structure

sequence of a chain of amino acids, polypeptide

Secondary protein structure:

hydrogen bonding of the peptide backbone causes amino acids to fold into a repeating pattern

Tertiary protein structure:

3d folding pattern of a protein due to side chain interactions

Quaternary protein structure:

protein consisting of more than one amino acid chain

Bonds that hold proteins in place:
Ionic bond forms between..

r group with a full negative charge and one with a full positive charge, stronger than hydrogen bond

Ionic bonds can be broken by..

change in pH

Hydrogen bonds form when a..

a group with a slight negative charge is attracted to one with a slight positive charge, weak bond

Hydrogen bonds can be easily broken by…

high temperatures or a change in pH

Hydrophobic bonds:
R group containing only carbon and hydrogen atoms are hydrophobic…

hydrophobic r groups tend to be found together as water's nearly always present

The slight attraction between these hydrophobic R groups is called a… and it is…

hydrophobic bond, weak

Disulfide bonds form between..

r groups of amino acid cysteine, very strong covalent bonds

Disulfide bonds can be broken by…

reducing agents

Disulfide bonds are important in…

holding different polypeptide chains in quaternary structure

Determining the structure of proteins is useful for…

understanding how a protein works and how diseases develop to find new medicines and make synthetic proteins

Structure of proteins can be determined by…

ab inito protein modelling or comparative protein modelling

Ab inito protein modelling is a model built based on the…

physical and electrical properties of the atoms in each amino acid in the sequence

Ab inito protein modelling can lead to multiple solutions to same amino acids, so…

other methods sometimes need applying to reduce num of solutions

Comparative protein modelling contains…

protein threading, scans amino acid sequence against database of solved structures, producing a set of possible models matching that sequence

Each amino acid has a different R group.
Describe how these R groups can interact to determine the tertiary structure of a protein. (4 marks)

hydrogen bonds form between polar r groups,
ionic bonds form between oppositely charged positive and negative r groups,
disulfide bonds form between cysteine,
hydrophobic r groups on inside of protein, hydrophilic on outside