Biology 2.2.10 fibrous and globular proteins

OCR A

What are Globular proteins ?

• Compact and rounded

• Soluble

• Polar

What type of protein is Hämoglobin and what features does it contain ?

• globular protein

• Quaternary structure

• Helical made of 4 polypeptide chain- 2 alpha and 2 beta globular chains

• 4 Haem group= prosthetic group ( conjugated protein ) containing an iron ion

• Oxygen binds to the haem group and transports round the blood

What type of protein is Insulin and what features does it contain ?

• globular protein

• Quaternary structure

• 2 polypeptide chains joined by disulphide bridges

• The chain A begins with a section of alpha helix and chain B ends with a beta pleated sheets

• The amino acids and hydrophilic R group and on the outside therefore solvable in water

• Binds to glycoprotein receptors on muscle/ fact cells- increase glucose uptake

What type of protein is pepsin and what features does it contain ?

• globular protein

• SYMMETRICAL Tertiary structure

• Made up of a single polypeptide chain with 327 amino acids

• Contains many H+ bonds and 2 disulphide bridges

• Has 43 amino acids within its acidic R group hence keeps a stable environment in the stomach

What type of protein is Amylase and what features does it contain ?

• Globular proteins

• Tertiary structure

• Secondary structure - consists of both alpha helix and beta plated sheets

What are fibrous proteins ?

• tough and roped shaped

• Regular repetitive amino acid sequence

• Structural proteins

• Insoluble and un-reactive

What type of protein is Collagen and what features does it contain ?

• Fibrous protein

• Mechanical strength

• Triple helix shape

• Minerals can bind to protein to increase rigidity

What are some examples where Collagen is found ?

• artery wall - withstand high pressure to prevent bursting

• Tendons - connects muscle to bone

• Bones -reinforced with calcium phosphate to make them hard

• Cartilage —connective tissue

What type of protein is Keratin and what features does it contain ?

• Fibrous protein

• Many cystine therefore lots of disulphide bridges Therefore very strong

• Provides mechanical protection and an impermeable barrier to infection and and it’s waterproof

• Found in hair skin and horns

What type of protein is Elastin and what features does it contain ?

• fibrous proteins

• Contains lots of tropelatsin which are coiled and cross linked

• It can stretch and relax - so it can return to original shape

• It can create large insolvable molecules

What are some examples where Elastin is found ?

• skin- stretch around bone

• Lungs - helps to inflate and deflate

• Bladder -expands and holds urine

• Blood vessels -stretches and recoils to help maintain pressure of blood