Lipids

Question 1

Different types of lipids are carachterized by a variety of structures and functional groups, but they all have what same defining characteristic?

Answer 1

Low solubility in water and high solubility in nonpolar organic solvents

Question 2

What are the main functions of lipids? What structural components are associated with each function?

Answer 2

1. Energy Storage; Long carbon chains
2. Cellular organization and structure (particularly in the membrane); Barriers separate aqueous environments because they are hydrophobic
3. Provision of precursor molecules for vitamins and hormones; Useful as precursors for signalling molecules because they can pass through cellular membranes

Question 3

Triacylglycerols

Answer 3

Glycerol backbone attached to 3 fatty acid chains. Main function is to store energy; can also provide thermal insulation and padding

Sometimes referred to as a fatty acid

(Also called triglycerides, or simply fats and oils)

Question 4

Phospholipids

Answer 4

Of particular importance are Phosphoglycerides:

Glycerol backbone, 2 fatty acid tails, and a polar phosphate group; Amphipathic, and is therefore well suited as the major component of biological membranes

Sometimes referred to as a fatty acid

Question 5

Amphipathic

Answer 5

Molecules with both polar and nonpolar groups

Question 6

Amphoteric

Answer 6

A molecule able to act both as an acid and a base

Question 7

Aliphatic

Answer 7

Relating to or denoting organic compounds in which carbon atoms form open chains (as in the alkanes), not aromatic rings

Question 8

Phosphatids

Answer 8

Glycerol backbone with phosphate attached;

A part of most phosphoglycerides

Question 9

Glycolipids

Answer 9

Similar to phosphoglycerides, except that glycolipids have one or more carbohydrates attached to the three-carbon glycerol backbone instead of the phosphate group.

Found in abundance in the membranes of myelinated cells in the nervous system

Question 10

Sphingolipids

Answer 10

Has a long chain fatty acid and a polar head group; Backbone molecule is an amino alcohol called a sphingosine

Make up part of the cell membrane

Question 11

Sphingomyelin

Answer 11

A type of sphingolipid: has a phosphate group attached to the sphingosine backbone

Question 12

What types of lipids make up part of the cell membrane?

Answer 12

Phospholipids/phosphatids

Glycolipids

Steroids

Sphingolipids

Question 13

Steroids

Answer 13

Four ringed structures

Includes some hormones, vitamin D, and cholesterol

Question 14

Terpenes and terpenoids function

Answer 14

Precursor molecules that feed into various biosynthesis pathways that produce important products - ex. Steroids and vitamin A

Question 15

Cholesterol

Answer 15

• major component of phospholipid bilayer
• at low temps prevents cell membrane from solidifying
• at high temps holds membrane together/prevents it from becoming too permeable
• precursor for steroid hormones, bile acids, and Vitamin D

Question 16

Prostaglandins

Answer 16

Autocrine and paracrine hormones that regulate cAMP levels. Have powerful effects on muscle contraction, body temp, the sleep-wake cycle, and pain.

Question 17

Fat-soluble vitamins

Answer 17

Vitamin A (Carotene) 
Vitamin D (Cholecalciferol) 
Vitamin E (Tocopherols) 
Vitamin K (phylloquinone and menaquinone)

Question 18

What does Vitamin A metabolize into?

Answer 18

Retinal for vision and retinoic acid for gene expression in epithelial development

Question 19

What does Vitamin D metabolize into?

Answer 19

Calcitrol in the kidneys - regulates calcium and phosphorous homeostasis in the intestines promoting bone formation.

Deficiency in Vitamin D causes rickets

Question 20

What does Vitamin E act as in the body?

Answer 20

It acts as a biological antioxidant. Its aromatic ring destroy free radicals, preventing oxidative damage.

Question 21

What is Vitamin K involved in?

Answer 21

It’s important for formation of prothrombin, a clotting factor. It performs posttranslational modifications on a number of proteins, creating calcium-binding sites.

Question 22

Saponification

Answer 22

The ester hydrolysis of Triacylglycerols using a strong base like potassium hydroxide

Question 23

Surfactant and how it acts like a soap

Answer 23

Lowers the surface tension at the surface of a liquid
Soaps acts as surfactants and form micelles.