1. Chapter 5 Section 4 Proteins Mrs. Kerstetter Biology

2. Proteins = polymer constructed of just 20 kinds of monomers called amino acids. Proteins are macromolecules that contain nitrogen, carbon, hydrogen, and oxygen

3. Functions of Proteins Functions: 1. Form structures (hair, fur, nails) 2. Make up muscles 3. Long-term nutrient storage 4. Circulate in blood and defend against harmful microorganisms 5. Convey signals or messages 6. Controls chemical reactions in a cell

4. Amino Acids Amino acids have a central carbon atom bonded to 4 other groups Amino acids have a central carbon atom bonded to 4 other groups THREE of those groups are the same in all amino acids THREE of those groups are the same in all amino acids They are: They are: 1. A HYDROGEN atom 2. A CARBOXYL group 3. An AMINO group

5. Amino Acids The 4 th group is called the “R group” The 4 th group is called the “R group” R group is responsible for the chemical properties of each amino acid R group is responsible for the chemical properties of each amino acid

6. Proteins

7. Building a Protein Cells link together amino acids into a chain called a POLYPEPTIDE. Cells link together amino acids into a chain called a POLYPEPTIDE. Created by a dehydration reaction between amino group of one amino acid and carboxyl group of next Created by a dehydration reaction between amino group of one amino acid and carboxyl group of next Proteins are made of one or more polypeptide chains Proteins are made of one or more polypeptide chains

8. Polypeptide Chains Most polypeptide chains are at least 100 amino acids in length Most polypeptide chains are at least 100 amino acids in length Each protein has a unique sequence of amino acids Each protein has a unique sequence of amino acids

9. Protein molecule Amino acid

10. Protein Shape Proteins that are linked to each other can’t just function… it needs a certain shape Proteins that are linked to each other can’t just function… it needs a certain shape Some side groups form bonds with each other causes folds, twists, and coils Some side groups form bonds with each other causes folds, twists, and coils Some shapes influenced by aqueous environment Some shapes influenced by aqueous environment Hydrophilic to outside and hydrophobic to inside Hydrophilic to outside and hydrophobic to inside

11. Denaturation Denaturation is the process of a protein losing its normal shape Denaturation is the process of a protein losing its normal shape Caused by changes in: Caused by changes in: 1. Temperature 2. pH 3. Some other environmental change A protein that loses its shape also loses the ability to work properly