2.1.2 Biological Molecules – Quaternary Structure Flashcards
(15 cards)
What are the two main types of proteins?
Fibrous and globular
Give three key features of globular proteins
- Spherical/rounded shape
- Soluble in water
- Usually have a metabolic function
Give three examples of globular proteins
Haemoglobin, enzymes (e.g. pepsin) and insulin
What is a conjugated protein?
A globular protein with a prosthetic group.
What is a prosthetic group?
A non-protein molecule that is attached to the protein.
Give one example of a conjugated protein
Haemoglobin
What is the prosthetic group in haemoglobin?
A haem group, containing an iron ion
What is the structure of haemoglobin?
It contains 4 polypeptide chains, each with 1 haem group. There are two polypeptides known as alpha-globin chains and two known as beta globin chains.
What is the function of pepsin?
It is a protease enzyme that digests protein in the stomach.
What is the function of insulin?
To bind to receptors on muscle and liver cells, increasing their uptake of glucose and leading to lower blood glucose levels.
Give three key features of fibrous proteins
- Long/elongated shape
- Insoluble in water
- Usually have a function related to strength/flexibility
Give three examples of fibrous proteins
Keratin, collage and, elastin (elastic fibres)
What is the function of keratin?
It is found in nails, hair, hooves, claws, fur and feathers. It provides a waterproof barrier and provides protection from infection.
What is the function of collagen?
Found in artery walls (to prevent bursting under high pressure), tendons, bones, cartilage and connective tissue. It provides mechanical strength.
What is the function of elastin?
Found in the skin, blood vessel walls and walls of the alveoli and bronchioles. It allows stretch and recoil, to ensure structures return to their original shape.
