Summary of Chapter 5.4

Vocabulary:
protein: a polymer constructed from a set of just 20 kinds of monomers called amino acids
amino acid: monomer that makes up proteins; contains carboxyl and amino functional group
polypeptide: chain of linked amino acids
denaturation: loss of normal shape of a protein due to heat or other facts

Proteins perform most functions in cells. They are responsible for most of the day-to-day functioning of organisms. They form hair and fur, make up muscles, and provide long term storages. Proteins defend the body from harmful microorganisms. Amino acids are monomers consiting of a central carbon atom bonded to four partners ( a carbon atom which forms four covalent bonds ). Cells create protein by creating a polypeptide. Each link is created by a dehydration reaction between the amino group of one amino acid and the carboxyl group of the next amino acid in the chain. Proteins can be formed by one more polypeptide chains. Proteins in their simple form of amino acids linked cannot function properly. Hydrophilic amino acids are towards the outside edges of protein while hydrophobic amino acids are towards the center of the protein. Any change in temperature, pH, or other qualities of environments can causea protein to unravel and lose its normal shape.

Concept Check 5.4
1. Give at least two examples of proteins you can "see" in the world around you. What are their functions?
Two examples are animal hair and fur, and the muscles. The animal hair and fur protects your outside part ( the skin ) and the muscles strengthen you.
2. Relate amino acids, polypeptides, and proteins.
Protein is a polymer constructed from set of 20 kinds of monomers called amino acids, and polypeptides are chains of linking amino acids, which makes proteins.
3. Explain how heat can destroy a protein. Heat can destroy proteins when the polypeptide chains become tangled with one another. Heating unfolds proteins because most of the forces that maintain folding are weak attractions between pairs of side groups, and between side groups and water. Hot molecules collide with force to overcome the weak attraction. Because the function of proteins depend on its shape, they lose their ability to work properly.
4. Which parts of an amino acid's structure are the same in all amino acids? Which part is unique? All amino acids have the hydrogen atom, an amino, and the carboxyl group. The fourth part is unique because it creates the protein's properties.