Please help.List four different types of lipids and briefly describe each one?

Question

I need to know the answer to this. It is for my biology homework and I cant find it in the book or on the powerpoint slide. 10 points to the first right answer.

Thanks

Answer 1

Firstly, lipids are a group of molecules that includes pretty much all fat and oil soluble naturally occurring molecules!

They include

- Fats

- Oils

- Waxes

There are many examples of lipids, but i'm going to list the four that I know the best.

1) Fatty acids

These are one of the most important groups of lipids. They are ALL carboxylic acids, consisting of

- The CARBOXYLIC ACID group (-COOH)

- A HYDROCARBON CHAIN

Fatty acids can be described as SATURATED or UNSATURATED

- SATURATED = The ENTIRE hydrocarbon chain is in the form -(CH2)nCH3. In other words, there are NO C=C DOUBLE BONDS IN THE HYDOCARBON CHAIN

- UNSATURATED = Parts of the chain have C=C DOUBLE BONDS. The carbon atoms are effectively not 'saturated' with the maximum number of hydrogen atoms (hence the term 'unsaturated')

2) Triglycerides

A tryglyceride is a glycerol molecule that has been ESTERIFIED with THREE FATTY ACIDS

What this means is that a molecule of glycerol (C3H6O3) has undergone a CONDENSATION REACTION with three fatty acid molecules

It is called a condensation reaction because THREE WATER MOLECULES ARE REMOVED when the bond is formed (:

3) Phospholipids

These are glycerol molecules that have been ESTERIFIED with:

- TWO fatty acids

- A POLAR PHOSPHATE GROUP

Now, fatty acids are long molecules. So a phospholipid appears to have 'TWO TAILS' and a 'HEAD'

- The hydrocarbon tails are NON POLAR

- The phosphate 'heads' are VERY POLAR

This leads to what is called a DIPOLE with a POLAR end and a NON POLAR end.

They make up the structure of cell membranes (: (Post a question about this to me if you want to know more about this function (: )

4) Steroids

These all have the same basic structure consisting of FOUR CARBON RINGS

- Three 6 carbon rings

- One single carbon ring

An example is cholesterol. They are often used by the body to synthesise HORMONES, as small (or sometimes large) groups are added to cholesterol (the most basic steroid) to make a different molecule (:

When you hear about abuse of 'steroids' in sporting competitions, a common example is the use of the male hormone TESTOSTERONE, which promotes

- muscle growth

- aggressiveness

However, urine samples can be analysed, and if testosterone is detected above normal expected levels, penal action is taken (:

(Remember, not all hormones are steroids.)

(To be quite frank, i'd put this as more of a biochemistry question than a biology question. I'd reccomend giving something like this to the chemists... like me next time (: )

x

Answer 2

http://www.sou.edu/chem/ch106/106ch18.ht...

Answer 3

Take a look at Wikipedia:

http://en.wikipedia.org/wiki/Lipid#Categ...