Lesson 7c: Proteins

Proteins: 15:56: http://player.discoveryeducation.com/index.cfm?guidAssetId=3C298D27-1A03-4CDD-B086-248C1B1A3F8E&blnFromSearch=1&productcode=US

Proteins:

2006-2007

Multipurpose molecules

collagen (skin)

Proteins Examples

muscle skin, hair, fingernails, claws

collagen, keratin

pepsin digestive enzyme

in stomach

insulin hormone that controls blood

sugar levels

insulin

pepsin

Proteins Function:

many, many functions hormones

signals from one body system to anotherinsulin

movementmuscle

immune systemprotect against germs

enzymeshelp chemical reactions

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

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

Water-fearing amino acids Hydrophobic (phobia – fear)

“water fearing” amino acids try to get away from water in cell – but HOW?

the protein folds

Water-loving amino acids Hydrophillic (phil – love)

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

the protein folds

pepsin

3-D protein structure Proteins fold & twist into 3-D shape

that’s what happens in the cell!

Different shapes = different jobs

collagen

hemoglobingrowth

hormone

Its 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 Biology,it’s not the size,it’s the SHAPEthat matters!