BS: Lipids 3

Question 1

Define derived lipids

Answer 1

Lipids obtained by hydrolysis of simple or complex lipids

Question 2

What are examples of derived lipids?

Answer 2

1. eicosanoids
2. prostaglandins
3. steroids
4. sterol
5. ergosterol
6. cholesterol
7. steroid hormone
8. steroid acids
9. fat soluble vitamins

Question 3

Define eicosanoids

Answer 3

compounds derived from:
- open chain
- 20 carbon
- polyunsaturated fatty acid (PUFA)

most frequently arachidonic acid

Question 4

What is the biological importance of eicosanoids?

Answer 4

• local hormones
• synthesized by all cell
• not stored in tissues
• synthesized as needed in response to physiological processes & in inflammation

Question 5

What are 2 types of eicosanoids?

Answer 5

1. cyclic
2. acyclic

Question 6

What are cyclic eicosanoids?

Answer 6

• formed by cyclo-oxygenase
  includes:
  1. prosanoids
  a) prostaglandin (PG)
  b) prostacyclin (PGI)
  c) thromboxan (TX)

Question 7

What are acyclic eicosanoids?

Answer 7

• they are formed by lipo-oxygenase
  include:
  1. leukotrienes (LT)
  2. lipoxins (LX)

Question 8

What does eicosanoid mean?

Answer 8

eicosa comes from the Greek word for 20.

Question 9

Define prostaglandins

Answer 9

group of cyclic fatty acid compounds classified as eicosanoids.
- represent as PG

Question 10

What types of PG are there?

Answer 10

several, including:
1. PGD
2. PGE
3. PGF

the designated letters indicate variations in chemical structure & functional groups attached to the cyclopentane ring

Question 11

How are prostaglandins synthesized?

Answer 11

• in: cells
• from: arachidonic acid
• by: cyclo-oxygenases & terminal prostaglandin synthases (enzymes)

Question 12

What are the types of cyclo-oxygenases?

& what inhibits them

Answer 12

1. COX-1: catalyzes production of prostaglandins for normal physiological functions
2. COX-2: catalyzes production of prostaglandins in inflammation

both COX-1 & COX-2 are inhibited by non-steroidal anti-inflammatory drugs (NAIDs)
- ex. aspirin & ibuprofen

Question 12

Define steroids

Answer 12

• lipids that have a tetracyclic ring structure [steroid nucleus]
• tetracyclic-cyclopentano-perhydro-phenanthrene
• a biological lipid (found in animals & plants)

Question 13

What is the structure of steroids?

Answer 13

• 4 rings: rings A, B, C, & D
• 17 carbons
• 28 hydrogen atoms
• ABC (3 rings) are cyclohexane rings
• 1 ring (D) is a cyclopentane ring
• no fatty acids
• may have a short hydrocarbon tail (ex. cholestrol and several other steroids)