Biological Molecules: Proteins

Question 1

Secondary protein structure - the Alpha Helices

Answer 1

Polypeptide winds into helix, creating a very stable structure

Question 2

Secondary protein structure

Answer 2

This is the way the primary polypeptide chain folds and coils: this forms a beta pleated sheet or alpha helices. The bonds forming these structure are hydrogen bonds.

Question 3

Protein functions

Answer 3

Toxins (e.g diphtheria toxin)
- Antifreeze (e.g glycoproteins in arctic fleas)
- DNA
- Lubrication (e.g glycoproteins)
- Hormones (e.g insulin)
- Enzymes (e.g amylase)
- Pumps (e.g Na + pump in cell membrane)
- Storage (e.g albumins in egg)
- Receptor (e.g motor neurons/rhodopsin)
- Blood clotting (e.g fibrin)
- Stucture (e.g collagen in bone)
- Antibodies (e.g immunoglobulins)
- Motors (e.g myosin in muscles)

Question 4

Protein composition

Answer 4

Always contains elements carbon, hydrogen, oxygen and nitrogen.Proteins are the most diverse and important group of biological compounds

Question 5

Primary structure

Answer 5

The sequence of amino acids in the polypeptide chain:
- This is the sequence of amino acids that makes a polypeptide chain, held by peptide bonds
- Primary structure determines the ultimate shape of the protein
- Peptide bonds maintain the structure
- Limitless number of combinations so protein varies considerably

Question 6

Tertiary protein structure

Answer 6

The way the polypeptide folds into a unique and specific 3D shape. There are limitless possibilities.

Question 7

Quaternary structure

Answer 7

Proteins made of more than one polypeptide structure joined together e.g haemoglobin and antibodies

Question 8

Secondary protein structure - the beta pleated sheet

Answer 8

Polypeptide chain zig-zags forming a pleated sheet. Formed by hydrogen bonds.