1. PROTEINS

2. Characteristics of Proteins
Contain carbon, hydrogen, oxygen, nitrogen, and sulfur
Serve as structural components of animals
Serve as control molecules (enzymes)
Serve as transport and messenger molecules
Basic building block is the amino acid

3. Proteins Function: many, many functions hormones movement
signals from one body system to another
insulin
movement
muscle
immune system
protect against germs
enzymes
help chemical reactions

4. Amino Acid Amine group acts like a base, tends to be positive.
Carboxyl group acts like an acid, tends to be negative.
“R” group is variable, from 1 atom to 20.
Two amino acids join together to form a dipeptide.
Adjacent carboxyl and amino groups bond together.

5. Amino acid chains Each amino acid is different
Proteins
amino acids chained into a polymer
amino acid
Each amino acid is different
some “like” water & dissolve in it
some “fear” water & separate from it

6. Some Amino Acids

7. Some More Amino Acids

8. Still More Amino Acids

9. Formation of a Dipeptide
Dehydration synthesis

10. Amino Acid + Amino Acid --> Dipeptide
Amino Acid + Dipeptide --> Tripeptide
A.A. + A.A. + …..+ Tripeptide --> Polypeptide

11. Water-fearing amino acids
Hydrophobic
“water fearing” amino acids
try to get away from water in cell
the protein folds

12. Water-loving amino acids
Hydrophillic
“water loving” amino acids
try to stay in water in cell
the protein folds

13. A protein consists of one or more
polypeptide chains.

14. 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
pepsin
collagen

15. 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)
unfolded “denatured”
In Biology,
it’s not the size,
it’s the SHAPE that matters!
folded