(O) The properties and functions of fibrous proteins

What makes fibrous proteins insoluble

Large proportion of amino acids with hydrophobic R groups

What kind of role do fibrous proteins play?

Structural role e.g bones

What kind of molecules does fibrous proteins form

Long rope like molecules

Where do you find collagen

Tendons (connects muscle to bones)

Ligaments ( connects bones to each other)

Skin

How is collagen strong?> (3)

COLLAGEN FORMS TRIPLE HELIX VIA POLYPEPTIDE CHAINS

Every 3rd amino acid is glycine which has a hydrogen R group (*makes it the smallest R group in an amino acid*) - allow collagen to wrap very closely to each other - as wrap around hydrogen bonds form which then stabilises the quarterly structure

Popypetode chains are joined by strong cross links with different molecules

Large numbe of triple helical Molecules join together to become staggered molecules with no weak sports which increases the strength of collagen

Where can Keratin be found?

Hair

Surface of skin

Nails

What are 3 properties of keratin

Inflexible

Insoluble

Extremely strong

Why is there n unpleasant smell when hair/nails burnt

Keratin contains high proportions of cysteine (a.a)

Meaning there are large numbers of disulphide bonds - INCREASES STRENGTH

What makes hair more flexible than nails

Hair has fewer disulphide bonds than nails making it more flexible

Wher is elastin found

In elastic fibres

Blood vessel walls

Alveoli in lungs

Why is elastin found in walls of blood vessels or alveoli

Gives flexibility to expan when needed but also go back to o.g shape

What type of structure dos elastin have

Quarternary