How cells work - the molecules

Question 1

Define a monomer.

Answer 1

A single molecule which can be bonded to other identical molecules to form a polymer.

Question 2

Define a dimer.

Answer 2

A molecular complex consisting of two identical molecules linked together.

Question 3

Define a multimer.

Answer 3

A molecule made up of multiple similar subunits, held together by non-covalent bonds.

Question 4

Define an oligomer.

Answer 4

A polymer whose molecules consist of relatively few repeating units.

Question 5

Define a polymer.

Answer 5

A large molecular complex made up of many repeating monomer subunits.

Question 6

Define a heterodimer.

Answer 6

A molecule complex with two different monomers.

Question 7

Define a homodimer.

Answer 7

A molecule complex with two of the same monomers.

Question 8

How are DNA/RNA polymerase proteins composed?

Answer 8

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.

Question 9

What is an amino acid and how is it comprised?

Answer 9

A monomer of proteins.
Comprised of:
Amino group.
R group, determines which amino acid it will be.
Carboxyl group, contains a chiral carbon.

Question 10

Which type of reaction occurs between amino acids to form polypeptides and where on amino acids do they form?

Answer 10

Condensation reactions form peptide bonds.
Peptide bonds are between the nitrogen atom of one and Carbon atom of another.

Question 11

What is glycogen?

Answer 11

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.

Question 12

Which two ways can proteins be modified by sugar chains?

Answer 12

O-linked glycosylation and N-linked glycosylation.

Question 13

How does N-linkage occur between a protein and sugar chain?

Answer 13

Asparagine residue on a protein provides an amino group for N-linkage.

Question 14

How does O-linkage occur between a protein and a sugar chain?

Answer 14

Serine and threonine provide hydroxyl groups for O-linkage formation.

Question 15

What are proteoglycans?

Answer 15

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.

Question 16

How does the negative charge on sugar chains in proteoglycans affect the complex?

Answer 16

Causes sugar chains to extend out.
maximises size of molecule to form gel-like spongy matrices.

Question 17

How are proteoglycans often used?

Answer 17

As molecular sponges. They absorb impact.

Found throughout the extracellular matrix (between cells)

Question 18

How can the primary folding sequence of proteins be simple explained?

Answer 18

Raw sequence of amino acids.

Question 19

What are the two forms taken in secondary protein folding?

Answer 19

alpha helix:
Coil.
Beta sheet:
Anti-parallel sheet.

Question 20

How are beta sheets held together?

Answer 20

Held together by peptide-peptide interactions (H-bonds).
Enabled by molecular chemistry of the R-group of the amino acids.

Question 21

How is the tertiary structure formed in protein folding?

Answer 21

secondary structures fold to form a complex functional molecule.

Question 22

How is the tertiary structure of proteins stabilised?

Answer 22

By non-covalent interactions and disulphide bridges.
Metal ions used to stabilise proteins (normally found within the active site).

Question 23

How is the quaternary structure formed in protein folding?

Answer 23

Binding of multiple monomers to form a larger protein complex.