5.4 Proteins perform most functions in cell

The Functions of Proteins
1.protein is a polymer constructed from a set of just 20 kinds of monomers called amino acids
2.proteins are responsible for almost all of the day to day functioning of organisms
3.less-visible functional proteins circulate in the blood and defend body from harmful organisms
Amino Acids
1.amino acid monomer consists of a central carbon atom bonded to four partners
2.three of the central carbon's partners are the same in all amino acids
3.four partners: one hydrogen atom, two carboxyl group and one amino group
4.the side group of the amino acids attracts water
Building a Protein
1.cells create proteins by linking amino acids together into a chain called a polypeptide
2.each in 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
3.most polypeptide chains are at least 100 amino acids in length
Protein Shape
1.a protein in the simple form of amino acids linked together cannot function properly
2.a protein's shape is also influenced by the surrounding environment
3.an unfavorable change in temperature, pH, or some other quality of the environment can cause a protein to unravel and lose its normal shape


Concept Check:
1. Give at least two examples of proteins you can "see" in the world around you. What are their functions?
Human's hair and muscles. Hair and muscles of humans provide long-term nutrient storage.

2. Relate amino acids, polypeptides, and proteins.
Polypeptides are chains linked by amino acids, and proteins are polypeptide molecules.

3. Explain how heat can destroy a protein.
Heat can make an unfavorable change in temperature, so the change can cause a protein to unravel and lose its normal shape.

4. Which parts of an amino acid's structure are the same in all amino acids? Which part is unique?
All amino acid consist of a central carbon bonded to an amino group, a carboxyl group, and a hydrogen atom. The side groups.