Lipoids

Question 1

What is the four types of lipoids?

Answer 1

1. Phosphoglycerides
2. Sphingolipids
3. Steroids
4. Carotenoids

Question 2

Types of phosphoglycerides:

Answer 2

Phosphatidic acid, lecithin, cephalin, inositol phosphatides, (plasmalogens)

Question 3

Types of Sphingolipids

Answer 3

Ceramide, sphingomyelin, cerebrosid, gangliosid

Question 4

Types of steroids:

Answer 4

-Sterols:
Zoosterols: Cholesterol
Phytosterol: Stigmasterol
Mycosterol: Ergosterol (vitamin D provitamin)

• Bile acids
• Steroid hormones

Question 5

Types of carotenoids:

Answer 5

Carotene, and carotene-like compounds (carotenoids), appear as pigments in many places in Nature.

• mangos
• butter
• Tomatoes

Question 6

Facts about phosphoglycerides:

Answer 6

Main role: membrane constituents.
General structure:
Amino alcohol: either cholamine or choline etc. Glycerol+ FA+P= =phosphatidic acid.

• Lecithin (emulsifier, cell membrane, choline)
• Cephalin (ethanolamine=cholamine, cell membrane of brain, blot clotting)
• Inositol phosphatides ( membrane constituents, 2nd messenger)
• Plasmalogens (platelet activating factor PAF)

Question 7

Facts about sphingolipids:

Answer 7

• Main role: membrane constituents
• Main constituents: a three carbon chain with two alcohols and amine attached and a long hydrocarbon chain.

Sphingolipids are a second type of lipid found in cell membranes, particularly nerve cells and brain tissues.

• Sphingomyelin ( nerve cell memebranes)
• Cerebrosid (galactose or glucose, nerural membranes)
• Gangliosid (sphingolipids that contain several carbohydrates)

Question 8

Facts about steroids:

Sterols and bile acids

Answer 8

Sterols:

-Zoosterols: Cholesterol (Makes the membrane less fluid and stronger, Synthesis: in the organism (liver, gonades, intestine), Bile acids and steroid hormones will be synthetised from cholesterol)

-Bile acids:
Primary bile acids produced in the liver: cholic acid and chenodeoxycholic acid.

Secondary bile acids produced in the intestine: deoxycholic acid and litocholic acid.

• Bile acids are facial amphipathic (if hydrophilic and hydrophobic). They have to important functions:
• Emulsification of lipid aggregates.
• Solubilization and transport of lipids in an aqueous environment.

-Bile acids are derivatives of cholesterol synthesized in the hepatocyte.

Action of bile salts in emulsifying fats in the intestine.

Question 9

Facts about steroids:

steroid hormones

Answer 9

• Pregnenolon (It is a common precursor). (KNOW STRUCTURE TO EXAM)
• Progesterone (female-luteal) (Vitamin A)
• Glycocorticoids: cortisol, cortisone, corticosterone.
• Mineralocorticoids: aldosterone, 11- deoxycorticosterone
• Androgens (male sex): testosterone, androsterone
• Estrogens (female sex): estrone, estriol, estradiol