Fibrous & Globular Proteins

Question 1

What are fibrous proteins?

Answer 1

long, thin, strong, insoluble proteins which are like ropes

connective tissue

quarternary structure - multiple polypeptide chains

have lots of bonding between polypeptides - makes them strong

Question 2

Give an example of fibrous proteins

Answer 2

collagen

keratin - structural protein found in hair, nails, skin + horns
elastin - stretchy, elastic connective tissue e.g. arteries stretch + recoil

Question 3

What is globular proteins?

Answer 3

round, spherical, soluble proteins
quarternary structure

hydrophobic R-groups fold on inside
hydrophilic R-groups fold on outside - makes it soluble in water - easily transported in blood

Question 4

Give an example of a globular protein

Answer 4

haemoglobin - 4 polypeptide chains

2 alpha chains
2 beta chains
4 haem groups (1 per polypeptide)

conjugulated protein - contain a non-polypeptide group

Question 5

What are other examples of globular proteins?

Answer 5

enzymes are globular proteins

insulim - hormone made by B-cells in islets of Langerhans in Pancreas by a single disulphide bridge