1. Lipids & proteins
SBI 4U

2. Lipids – long term energy!
Lipids are hydrophobic molecules
Insoluble in water, but soluble in other non- polar substances
Organisms need lipids for storing energy, building membranes and other cell parts, and as chemical signalling molecules
Four families of lipids: fats, phospholipids, steroids and waxes

3. Fats! Most common energy-storing molecules in living organisms
A very concentrated source of energy
Excess carbohydrate is turned into fat – animals store fat molecules as droplets in the cells of adipose tissue

4. Fats, continued … Oil  plant equivalent to fat Triglycerides
Both fats & oils composed of: glycerol and fatty acids
Glycerol  3-carbon alcohol, each carbon attached to a hydroxyl group  with condensation reaction, 3 fatty acids attached to this core
Fatty acid is a hydrocarbon chain, ending with a carboxyl group (-COOH)

5. Fats, continued

6. Saturated vs. unsaturated fats
Saturated Fat: No double bonds between the individual carbon atoms. Ex: lard, butter, cream and fatty meats
Unsaturated Fat: At least one double bond in the fatty acid chain. Ex: fish, canola oil and olive oil

7. Phospholipids
A class of lipids that are a major component of all cell membranes
Composed of: a glycerol molecule, two fatty acids and a highly polar phosphate group

8. phOSPHOLIPIDS CONTINUED…
When added to water, phospholipids form spheres, called micelles – the hydrophilic heads stay in the water and their hydrophobic tails mix with one another in the center of the sphere

9. STEROIDS Compact hydrophobic molecules
Cholesterol and sex hormones are examples of steroids
Cholesterol is important for membrane permeability – too much can increase risk for heart disease and stroke
Sex hormones (ex: testosterone & estrogen) control the development of sex traits and gametes

10. Waxes! Lipids containing long-chain fatty acids
Firm and flexible consistency
Produced by some animals (ex: bees) and plants
Often used for commercial coating purposes
Ex: cutin (produced by plants) helps protect surfaces of stems, leaves and fruits

11. What are proteins?
Any of a large group of nitrogenous organic compounds that are essential constituents of living cells; consist of polymers of amino acids; essential in the diet of animals for growth and for repair of tissues; can be obtained from meat and eggs and milk and legumes; "a diet high in protein"

12. Proteins continued… They are amino acid polymers
Structural characteristics determine function

13. Why are proteins important?
Used as structural blocks
Some are enzymes, that act as biological catalysts
Help transport materials through cell membranes and through the bodies of plants and animals (ex: hemoglobin)
Used in movement (major component of muscles)
Antibody proteins for immune protection

14. Amino acids
Building blocks of proteins

15. More about proteins!
Amino acid polymers twist and coil into a particular shape that defines the protein
An amino acid polymer is called polypeptide
Peptide bonds are the bonds that hold amino acids together