1. Unit 7: Molecular Genetics 7.6 Proteins

2. Structural Proteins
Fibrous proteins that create provide structure of the body.
Keratin: protein for hair and nails
Actin and myosin: proteins of muscle tissue
Collagens: protein for ligaments, tendons and skin

3. Functional Proteins
Functional proteins perform a specific function within the body.
Metabolic Processes: Proteins such as enzymes are catalysts for reactions
Growth and Repair: Proteins such as antibodies help fight disease
Communication: Protein hormones such as insulin communicate between cells and cell receptors help transport substances across the cell membrane

4. Basic Structure Basic Structure Monomer: amino acids
Contains the following molecules: CHON(s)
Amino Acids have common features.
Amino Group
Alpha Carbon
Carboxylic Acid Group
The “R” Group -different for each Amino Acid
Polar or Non-Polar (Hydrophilic or Hydrophobic)
Acidic or Basic
Contains Sulfur (forms disulfide bridges)
Called the “backbone”

5. The “R” Group Differs for Each Amino Acid
Structure
Amino Group    
The “R” Group Differs for Each Amino Acid
Carboxylic Acid Group
“Alpha” Carbon R
See p 34

6. Amino Acids: Leucine Structure
Amino Group  
Carboxylic Acid      Group
Leucine “R”      Group

7. Proteins in the Body There are 20 different amino acids used the body.
The body can synthesize 12 of the amino acids, but the rest must come from food.

8. Basic Structure Complex-polymer
Proteins are made up of chains of amino acids
The chain of amino acids is called a polypeptide.
The bond between amino acids is called a peptide bond and is created through dehydration synthesis.
Amino acids within the polypeptide interact with each other to create a well-defined 3-D structure. The correct structure is essential to the function of the protein.

9. 4 Levels of Protein Structure-Protein Folding
Primary Structure
Secondary Structure
Order of Amino Acids in the Chain
Determined by the gene on the DNA
Folding along short sections of the polypeptide
Caused by an interaction between the elements in the backbone of adjacent amino acids
Forms an  helix or a  pleated sheet

10. 4 Levels of Protein Structure-Protein Folding
Tertiary Structure
Quaternary Structure
Whole Molecule Folding caused by interactions between R-groups in distant amino acids.
Acids bond to bases
Hydrophilic to hydrophilic
Hydrophobic to hydrophobic
Sulfur to Sulfur (creates disulfide bridges)
Multiple polypeptide chains bonding to form a protein.

12. When Proteins Lose their Function
Proteins can be denatured.
Ex: heat causes it to lose its shape and its functionality.
pH can also cause the protein to lose its shape and functionality.

13. Proteins in Food
There are 8 essential amino acids that must be obtained from food.
Animal products, such as meat, fish, eggs, and milk, generally contain all eight essential amino acids.
Plant-based foods, such as grains and beans, do not and must be eaten in combination with other foods to obtain all 8 essential amino acids.
Example: Rice and Beans