Download Chapter 5 Section 4 Proteins

Chapter 5 Section 4
Proteins
Mrs. Kerstetter
Biology
Proteins
= polymer constructed of just 20 kinds of
monomers called amino acids.
Proteins are macromolecules that contain
nitrogen, carbon, hydrogen, and oxygen
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
Amino Acids


Amino acids have a central carbon atom
bonded to 4 other groups
THREE of those groups are the same in all
amino acids

1.
2.
3.
They are:
A HYDROGEN atom
A CARBOXYL group
An AMINO group
Amino Acids

The 4th group is called the “R group”

R group is responsible for the chemical
properties of each amino acid
Proteins
Building a Protein



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
Proteins are made of one or more polypeptide
chains
Polypeptide Chains

Most polypeptide chains are at least 100 amino
acids in length

Each protein has a unique sequence of amino
acids
Protein molecule
Amino acid
Protein 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 shapes influenced by aqueous
environment

Hydrophilic to outside and hydrophobic to inside
Denaturation


1.
2.
3.
Denaturation is the process of a protein losing its
normal shape
Caused by changes in:
Temperature
pH
Some other environmental change
A protein that loses its shape also loses the ability to work
properly