Chapter 5.4 Summary

Proteins perform most functions in cells.

The Functions of Proteins
protein
: a polymer constructed from a set of just 20 kinds of monomers called amino acids
- ex. forms hair, make up muscles
Amino Acids
amino acid
: monomer that makes up proteins; contains carboxyl and amino functional group
- 3 of the 4 partners are constant in all amino acids : amino group, carboxyle group, hydrogen group
- last group: side group/R-group determines the chemical properties of an amino acid

Building a Protein
polypeptide
: chain of linked amino acids to create proteins
- formed when dehydration reaction occurs between amino group and carboxyl group

Protein Shape
- proteins differ depending on the way their polypeptides are arranged
- protein can also be affected by the environment
- hydrophobic amino acids - towards inside of protein
- hydrophillic amino acids - extends to edge of protein
denaturation
: loss of normal shape of a protein due to heat or other facts

Concept Check

1. Give at least two example of proteins you can "see" in the world around you. What are their functions?
   Two examples of proteins we can "see" in the world around us are hair and muscles. Muscles strengthens you and hair keeps us warm.
2. Relate amino acids, polypeptides, and proteins.
   A protein, a polymer, is made of amino acids which are monomers that link together to form a chain called polypeptides. Polypeptide chains have around 100 amino acids.
3. Explain how heat can destroy a protein.
   Heat can destroy a protein and cause it to lose its normal shape because it breaks the bond that hold the molecules together.
4. Which parts of an amino acid's structure are the same in all amino acids? Which part is unique?
   Three of four of an amino acid's partners stay the same in all amino acids (amino group, carboxyle group, hydrogen group). The fourth group, R-group, is unique.