Proteins are large, complex, organic molecules made up of **amino acids**.
	- Contain carbon, hydrogen, oxygen, and nitrogen
	- Found in plants, animals, bacteria, and viruses
- Proteins also help maintain acid-base balance.
	- Maintaining the proper pH of body fluids
	- Act as a **buffer**
- Major functions of protein in the body:
	- To build new cells and many parts of cells
	- As a component in hardened structures like hair and nails
	- As enzymes to speed chemical reactions
	- As lubricants to ease movement
	- In clotting compounds in blood
	- To build antibodies that fight disease organisms
	- As compounds that help maintain fluid and pH balance
	- As transporters
	- To make certain hormones
	- As an energy source (as a last resort)
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# Introduction
- By helping to maintain fluid balance, proteins prevent **edema** (accumulation of fluid in tissues
- Proteins also help maintain **acid-base balance**.
	- Maintaining the proper pH of body fluids
	- Acts as a buffer

# Amino acids
- Amino acids are nitrogen containing chemical units that comprise proteins
- There are 20 different amino acids found in the proteins of the human body
- Each amino acid has a carbon atom that anchors
	- Hydrogen atom
	- Amino or nitrogen containing group
	- R group (side chain)
	- carboxylic acid group
- nonessential amino acids are a group of amino acids that the body can make
- Essential amino acids are amino acids the body cannot make or cannot make enough of to meet its needs
- Conditionally essential amino acids are the amino acids the body cannot make or cannot make enough of to meet its needs
- There are 9 essential acids and 11 non-essential acids
| Essential | Non