Proteins 3: Fibrous and globular proteins 2.2.10 Flashcards
What is a fibrous protein?
Has a relatively long and thin structure, which is insoluble in water - therefore having a structural role in an organism.
What is a globular protein?
Has a very spherical shape, which is soluble in water and often has functional roles in an organism.
What is the function of collagen?
It provides mechanical strength, for example tendons are made of collagen which connects muscle to bone, and in artery walls, a layer of collagen prevents the artery bursting from high pressure.
What is the function of keratin?
Keratin is very strong (as it is made from cysteine which forms lots of disulphide bridges) and is found in areas such as nails, hooves, and hair.
What is the function of elastin?
Elastin has a highly coiled structure, which makes it strong and extendable - and is found in living things such as skin and the lungs.
What is the structure of haemoglobin?
It has a quaternary structure of four polypeptide chains (two alpha globin and two beta globin).
It consists of a ham group (prosthetic group) which is not composed of amino acids.
Haemoglobin is therefore known as a conjugated protein.
What is the function of haemoglobin?
It carries oxygen from the lungs to the tissues. In the lungs, oxygen binds to the iron in each of the four haem groups in the haemoglobin molecule.
As oxygen binds, haemoglobin turns from a purple red colour to bright red. As it reaches the tissues, oxygen disassociates from the haemoglobin.
What is the function of insulin?
Insulin binds to glycoprotein receptors on the outside of muscle and fat cells to increase their uptake of glucose from the blood, and to increase their rate of consumption of glucose.
It is soluble in water (globular protein), which aids its function.
What is the function of pepsin?
An enzyme that digests protein in the stomach - and consists of many acidic R groups which is why it’s so stable within the stomach environment.
