Proteins
What are proteins?
• Chain of molecules of Amino Acids called a
polypeptide chain
• Found in: muscle, hormones, enzymes
• Monomers of proteins are amino acids
– 20 total AA
Major Functions of Proteins
1. Provide energy
2. Enzyme catalyst: speed up rxn
3. Defense: use shape to recognize foreign
invaders
4. Transport:
hemoglobin-oxygen
to RBC
5. Support: fibrous
proteins
1. Fibrin in blood clots
2. Collagen-matrix of
skin
Amino Acids
• Monomers of Proteins
• All contain:
1. Amino group NH2
2. Carboxyl group –COOH
3. R group
-different for every AA
-determines the
properties of AA
Joined together by peptide
bonds
Peptide Bonds
• Amino acids join together by peptide bond
• Forms when amino end of one AA joins to
carboxyl end of another AA by
dehydration synthesis.
http://science.nhmccd.edu/BioL/dehydrat/dehydrat.html
•
Protein structures
As AA join, R groups interact and cause
molecules to bond
1.
2.
3.
4.
Primary-straight chain
Secondary-helix
Tertiary-mass
Quaternary-2 proteins combined
Enzymes
• All enzymes are proteins
• Speed up chemical rxn; catalyst
• Shape of protein allows it to bond to
specific molecules called substrates, causes
a change in shape
Examples maltase: breaks down maltose into 2 glucose
lipase: breaks down lipids into fatty acids
protease: breaks down proteins into amino
acids
**works best under certain temperatures or pH
Enzymes