1. C-Notes: Proteins General Structure
Stnd: BI.5a
C-Notes: Proteins General Structure
9/16/13
SWBAT identify proteins general structures and functions in cells.
Objective:

2. What are the structures of proteins?
Proteins are made of chains of AMINO ACIDS.
There are only 20 amino acids and can be combined in nearly countless ways.
The sequence of amino acids determines the shape of the protein. The shape of the protein is the biggest factor that determines its function.
There are 4 levels of structure
Primary structure
Linear shape (straight line)
Secondary structure (2 types)
Folding of protein structure
-helix (spiral shape) and -sheets (folded shape)
Tertiary structure
actual 3D shape
Quaternary structure
When 2 or more smaller polypeptides w/ different shapes join together.
Any alteration in the structure or sequencing changes the shape and function of the protein

3. Secondary Protein Structure
Amino acid
subunits
b pleated sheet
Amino acid
subunits
 helix
b pleated sheet
 helix

4. Polypeptide chain b Chains Iron Heme a Chains Hemoglobin
LE 5-20e
Polypeptide
chain
b Chains
Iron
Heme
a Chains
Hemoglobin
Polypeptide chain
Collagen

5. What happens when enzymes (proteins) Denature?
Because proteins shape are affected by temperature and pH changes.
It loses its normal shape when it is not in ideal optimal environmental conditions.
When a protein loses its normal shape, this is called denaturing.
A denatured protein is biologically INACTIVE.
Denaturing is usually permanent and not reversible.

6. Denaturing a Protein
Figure 6.5

7. For enzymes… What matters?
SHAPE!

8. Structural Differences Between Carbohydrates, Lipids, and Proteins
Figure 6.1