Lecture 11 - Lipids and Fatty Acids

Question 1

Lipid Characteristics

Answer 1

Exist in both animals and plants
Known as fats, waxes, and oils
Insoluble in water
Soluble in organic lipids

Question 2

Fatty Acids

Answer 2

Hydrocarbon derivative
Carboxylic acids with hydrocarbon chains of 4-36 C’s
Hydrophilic head and hydrophobic tail
Saturated when it is a straight molecule and unsaturated when kinked

Question 3

Fatty acids are amphipathic which allows them to form what?

Answer 3

Miscelles and other lipid aggregates

Emulsions (miscelle like droplets) of lipids in aqueous solution

Question 4

How does the length of the hydrocarbon chain and degree of saturation affect fluidity

Answer 4

Longer chains and decreased unsaturation - decreased fluidity
Shorter chains and increased unsaturation - increased fluidity

Question 5

Trans Fats

Answer 5

Result from partial hydrogenation
Hydrogenation would convert all DBs to single bonds
Partial hydrogenation results in conversion of cis DBs to trans DBs

Question 6

Affects of Trans Fats

Answer 6

Increase LDL in humans
Increase inflammaotry response
Increases risk of coronary heart disease

Question 7

Triacylglycerols

Answer 7

Glycerol and 3 fatty acids
They are the storage lipids
Found as oily droplets in cytosol

Question 8

Difference between white adipocytes or brown adipocytes

Answer 8

White - fat storing cells
Brown - used for heat production
Found under skin, abdominal cavity and mammory glands

Question 9

Waxes

Answer 9

Esters of long chain saturated and unsaturated fatty acids with long chain alcohols (16-30 C)
Used for energy stores and water impermeable coatings
Protective coats for insects, plants, hair

Question 10

Oils

Answer 10

Viscous liquid
Non-polar
Hydrophobic

Question 11

What are phospholipids important for?

Answer 11

Membrane structure
Cell signalling
Cell recognition

Question 12

Eicosanoids

Answer 12

Autocrine and paracrine hormones

Originate from polyunsaturated fatty acids with 20 C (arachidonic acid)

Question 13

Isoprenoids

Answer 13

Derived from isoprene unit
Synthesis of cholesterol
Two types:
Terpenes
- natural rubber
Sterols 
- basic component cholesterol and vitamin D
- found in eukaryotes only

Question 14

Cholesterol

Answer 14

Amphipathic
OH polar head
Important in:
- Membrane structure
- steroid hormones (testosterone, cortisol)
- Bile acids
- Major sterol in animals

Question 15

Types of Lipoproteins

Answer 15

Chylomicrons
- Transport vehicle for dietary lipids from intestine to peripheral tissues
VLDL
- very low density lipoproteins contain lipids and proteins
- transports lipids from liver to peripheral tissues
LDL
- Loss of triacylglycerol from VLDL produces LDL
- transports cholesterol to peripheral tissue
- Taken up by liver
HDL
- protein rich aggregate produced in liver and small intestine
- collects cholesterol and transports to liver

Question 16

Glycosphingolipids

Answer 16

Extremely important in plasma membrane - provides thickness so doesnt easily rupture
Cell to cell communication and interaction
Antigenic

Question 17

What are the two types of Signalling lipids?

Answer 17

Eicosanoids and Isoprenoids