fibrous proteins, collagen, keratin and elastin

how do fibrous proteins differ from globular proteins?

• they play a structural role in bones or tendons

• they form long rope molecules

• they contain a large proportion of amino acids with hydrophobic r groups, they are insoluble in water

what are the 3 fibrous proteinss?

• collagen

• keratin

• elastin

where is collagen found?

in tendons connecting muscles to bones and in ligaments connecting bones to eachother

what type of molecule is collagen?

a strong molecule

how do the polypeptide chains wrap in collagen, to form what?

they wrap tightly together to form a triple helix

in every collagen polypeptide, what is every third amino acid?

glycine

what is the r group of glycine?

hydrogen

how can the collagen polypeptides wrap tight around eachother?

glycine has the smallest r group of all amino acids allowing the polypeptides to wrap tightly around eachother

what are the polypeptide chains joined together by?

strong crosslinks

how is collagen strong?

as its molecules are staggered avoiding weak spots

where is keratin found?

hair, fingernails and the outer surface of skin

properties of keratin?

• extremely strong

• insoluble in water

what molecules does keratin consist of?

long fibrous molecules

what does keratin consist of a high portion of??

the amino acid cysteine

because keratin consist of lots of cysteine, what large number of bonds do they contain?

large number of disulfide bonds

where are elastin fibres found?

the skin and the arteries

are elastin molecules long or short containg hydrophobic or hydrophilic interactions?b

long strands containing hydrophobic regions

how are elastin strands linked together?

they are crosslinked