Proteins Biology

1. Proteins
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2. Proteins:
Multipurpose molecules
Regents Biology 2006-2007

3. Proteins
Examples
 muscle
insulin
 skin, hair, fingernails, claws
 collagen, keratin pepsin
 pepsin
 digestive enzyme
in stomach
 insulin
 hormone that controls blood
sugar levels
Regents Biology collagen (skin)

4. Proteins
 Function:
 many, many functions
 hormones
 signals from one body system to another
 insulin
 movement
 muscle
 immune system
 protect against germs
 enzymes
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5. Proteins
 Building block = amino acids
amino amino amino amino amino
acid – acid – acid – acid – acid
 20 different amino acids
H O There’s
20 of us…
H | || like 20 different
letters in an
—C—C—OH
—N— alphabet!
Can make lots of
H | different
variable words
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6. Amino acid chains
 Proteins
 amino acids chained into a polymer
amino acid amino acid amino acid amino acid amino acid
 Each amino acid is different
 some “like” water & dissolve in it
 some “fear” water & separate from it
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7. Water-fearing amino acids
 Hydrophobic
 “water fearing” amino acids
 try to get away from water in cell
 the protein folds
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8. Water-loving amino acids
 Hydrophillic
 “water loving” amino acids
 try to stay in water in cell
 the protein folds
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9. For proteins: SHAPE matters!
 Proteins fold & twist into 3-D shape
 that’s what happens in the cell!
 Different shapes = different jobs
growth
hormone hemoglobin
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pepsin
collagen

10. 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
unfolded
 pH (acidity)
“denatured”
In Biology,
it’s not the size,
it’s the SHAPE
that matters!
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11. Let’s E some
AT
Proteins!
Regents Biology 2006-2007

12. 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
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