Biology I

Proteins

Regents Biology 2006-2007

Proteins:

Multipurpose molecules

Biology I collagen (skin)

Proteins

insulin

Examples muscle skin, hair, fingernails, claws

collagen, keratin

pepsin digestive enzyme

in stomach

insulin hormone that controls blood

sugar levels

pepsin

Biology I

Proteins Function:

many, many functions hormones

signals from one body system to anotherinsulin

movementmuscle

immune systemprotect against germs

enzymeshelp chemical reactions

Biology I

Proteins

Building block =

aminoacid

aminoacid–

aminoacid–

aminoacid–

aminoacid–

—N—H

H

H|

—C—|

C—OH

||O

variable group

amino acids

20 different amino acidsThere’s

20 of us…like 20 different

letters in analphabet!

Can make lots of different

words

Biology I

Amino acid chains Proteins

amino acids chained into a polymer

Each amino acid is different some “like” water & dissolve in it

some “fear” water & separate from it

amino acid amino acid amino acid amino acid amino acid

Biology I

Water-fearing amino acids Hydrophobic

“water fearing” amino acids try to get away from water in cell

the protein folds

Biology I

Water-loving amino acids Hydrophillic

“water loving” amino acids try to stay in water in cell

the protein folds

Biology I pepsin

For proteins: SHAPE matters!

collagen

Proteins fold & twist into 3-D shape that’s what happens in the cell!

Different shapes = different jobs

hemoglobingrowth

hormone

Biology I

It’s SHAPE that matters! Proteins do their jobs, because

of their shape Unfolding a protein destroys its shape

wrong shape = can’t do its job unfolding proteins = “denature”

temperature pH (acidity)

folded

unfolded“denatured”

In Biologyit’s the SHAPEthat matters!

Biology I

Let’s EAT some

Proteins!

Biology I

Activities demo raw egg vs. cooked egg

drop raw egg into boiling water, like egg drop soup

compare raw egg to hard-boiled egg

demo cheese-making with heated milk & vinegar

make yogurt