1. Samantha Reese Danielle New Chanpisey Phy
Lipids
Samantha Reese Danielle New Chanpisey Phy

2. What are Lipids? Oils Fats Fatty Acid Triglycerides Phospholipids
Steroids ( including cholesterol)

3. Examples of lipids:
Lard
Vegetable oil
Phospholipids
Steroids

4. What is a lipid composed of?
Fatty acids:
long carbon skeleton
usually 16 or 18 carbon atoms in length.
Fatty acids make lipids hydrophobic
Fatty Acids are amphipathic molecules with the hydrocarbon tail serving as hydrophobic region and the carboxy group (-COOH) serving as a hydrophilic region.

5. Fats contain glycerol & Fatty Acids1 2 3

6. Fatty Acids:
Saturated fatty acids Unsaturated fatty acids

7. Fats are glycerol & Fatty Acids

8. Fatty Acids:
Saturated fatty acids Unsaturated fatty acids

9. Saturated Fatty Acids If there are no double bonds between carbon
atoms composing the chain, then as many hydrogen atoms as
possible are bonded to the carbon skeleton. Such a structure is
described as being saturated with hydrogen, so the resulting
fatty acid is called a saturated fatty acid.
Most animal fats are saturated:

10. Unsaturated Fatty Acids (Cis-Fats)
unsaturated fatty acid has one or more double bonds, formed
by the removal of hydrogen atoms from the carbon skeleton.
The fatty acid will have a kink in its hydrocarbon chain wherever
a cis double bond occurs.
fats of
plants and fishes are generally unsaturated, meaning that they
are built of one or more types of unsaturated fatty acids. Usually
liquid at room temperature, plant and fish fats are referred
to as oils-olive oil and cod liver oil are examples.

11. Trans Fat process of hydrogenating vegetable oils
produces not only saturated fats but also unsaturated fats with trans double bonds.

12. What are the Components of Phospholipids?
Most phospholipids contain a diglyceride, a phosphate group, and a simple organic molecule such as choline.

13. Phospholipids Bilayer
Source: Biology Campbell 8 ed.
In aqueous environment, phospholipids assemble itself in such a way that the hydrophilic heads are in contact with water while the hydrophobic tails are away from water. This arrangement formed phospholipids bilayer which is an important component of biological cell-membrane.

14. Phospholipids (Cont.)
Imagine in the case of plasma membrane. If we have only one single layer of phospholipids, the hydrophobic tails would then be exposed to water which is chemically unfavorable. As a result, the hydrophobic tail will then assemble itself in such a way that it would stay away from water as much as possible. This result in two phospholipids layer assembling itself such that the polar/hydrophilic region would be in contact with water whereas the non-polar/hydrophobic region would avoid contact with water leaving both polar head and non-polar tail happy.
In the case, of Micelle, monolayer of phospholipids would do anything in their power so that the hydrophobic fatty acids are away from water due to its water hating property. This explain why micelle is in a shape of a droplet with hydrophobic cell is in the inside whereas the hydrophilic head is in the outside.

15. Many Hormones are Lipids
Cholesterol is a lipid with a carbon skeleton with four fused rings
Cholesterol is the source of hormones that plays important role in biological endocrine system
Eg. Estrogen, Testosterone, Aldosterone

16. Lipids as Major Membrane Component
Cholesterol is one of major component of animal cell membranes.
the precursor from which other steroids are synthesized.
With cholesterol embedded in the cell membrane, phospholipids layer won’t be packed together as tightly. This hydrophobic integral of lipids (cholesterol) and proteins gives cell-membrane the flexibility to move laterally or sideways which is known as “fluid mosaic.”