How cells work - the molecules Flashcards
Define a monomer.
A single molecule which can be bonded to other identical molecules to form a polymer.
Define a dimer.
A molecular complex consisting of two identical molecules linked together.
Define a multimer.
A molecule made up of multiple similar subunits, held together by non-covalent bonds.
Define an oligomer.
A polymer whose molecules consist of relatively few repeating units.
Define a polymer.
A large molecular complex made up of many repeating monomer subunits.
Define a heterodimer.
A molecule complex with two different monomers.
Define a homodimer.
A molecule complex with two of the same monomers.
How are DNA/RNA polymerase proteins composed?
Active site of the enzyme is formed form one polypeptide.
The other polypeptides are involved in regulation by binding to other proteins and complexes to regulate the process.
What is an amino acid and how is it comprised?
A monomer of proteins.
Comprised of:
Amino group.
R group, determines which amino acid it will be.
Carboxyl group, contains a chiral carbon.
Which type of reaction occurs between amino acids to form polypeptides and where on amino acids do they form?
Condensation reactions form peptide bonds.
Peptide bonds are between the nitrogen atom of one and Carbon atom of another.
What is glycogen?
The major store of carbohydrates.
Composed of glucose and a protein complex core (glycogenin).
Multi branched.
Glycosidic 1-4 bonds in series.
Glycosidic 1-6 binds in branches.
Which two ways can proteins be modified by sugar chains?
O-linked glycosylation and N-linked glycosylation.
How does N-linkage occur between a protein and sugar chain?
Asparagine residue on a protein provides an amino group for N-linkage.
How does O-linkage occur between a protein and a sugar chain?
Serine and threonine provide hydroxyl groups for O-linkage formation.
What are proteoglycans?
Very large proteins with a very specific sugar attached.
A core protein covalently bonded to a GAG Chain.
GAG chain is a polysaccharide made of diasccharide building blocks.
Each disaccharide consists of an amino sugar and a uronic acid.
How does the negative charge on sugar chains in proteoglycans affect the complex?
Causes sugar chains to extend out.
maximises size of molecule to form gel-like spongy matrices.
How are proteoglycans often used?
As molecular sponges. They absorb impact.
Found throughout the extracellular matrix (between cells)
How can the primary folding sequence of proteins be simple explained?
Raw sequence of amino acids.
What are the two forms taken in secondary protein folding?
alpha helix:
Coil.
Beta sheet:
Anti-parallel sheet.
How are beta sheets held together?
Held together by peptide-peptide interactions (H-bonds).
Enabled by molecular chemistry of the R-group of the amino acids.
How is the tertiary structure formed in protein folding?
secondary structures fold to form a complex functional molecule.
How is the tertiary structure of proteins stabilised?
By non-covalent interactions and disulphide bridges.
Metal ions used to stabilise proteins (normally found within the active site).
How is the quaternary structure formed in protein folding?
Binding of multiple monomers to form a larger protein complex.
