LECTURE 15 - DIETARY LIPIDS

Question 1

what is the definition of lipids?

Answer 1

heterogeneous group of biological compounds including fats, oils, steroids, waxed, relatively insoluble in water

Question 2

what are common properties of lipids

Answer 2

relatively insoluble in water
soluble in nonpolar solvents (ether or chloroform)

Question 3

what are functions of lipids

Answer 3

energy storage
dietary compounds bc of their high energy
structural components of membranes
thermal insulators in subcutaneous tissues
signalling molecules
hormone precursors

Question 4

what structures do lipids form

Answer 4

micelles
polar heads face the polar core and lipids face the inside

Question 5

in what locations are lipids present and what are they involved in

Answer 5

plasma membrane: phospholipid remodelling
mitochondrion: beta oxidation
ER: phospholipid and neutral lipid biosynthesis
lipid storage droplets:lipolysis
cytosol: FA synthesis

Question 6

atherosclerosis

Answer 6

Question 7

what are purified lipids

Answer 7

triacylglycerol
comes from olive oil
neutral lipid

Question 8

what are cellular lipids

Answer 8

lipid droplets:
triacylglycerol
cholesteryl esters
-> neutral lipids
membrane lipids:
phospholipids
sphingolipids
glycolipids
cholesterol
-> amphipatic

Question 9

what are the different elements that help in the absorption of dietary lipids?

Answer 9

bile salts generate micelles
pancreatic lipase breaks down triglycerides
i-FABP(intestinal) (Fatty acid binding protein) helps to carry fatty acids inside the enterocyte

Question 10

how do lipids get from the diet to the blood?

Answer 10

1. mucosa
   absorption of FA+MAG
   absorption of sterole
2. ER: chylomicron assembly
   triacylglyceride
   cholesterol
   ApoB48
3. chylomicron secretion to circulation

Question 11

where are free fatty acids located in the cell?

Answer 11

mitochondrion and cytosol

Question 12

structure of a fatty acid

Answer 12

Question 13

difference between saturated and unsaturated in the membrane

Answer 13

Question 14

what is the relationship between number of carbons and melting point

Answer 14

number of carbons goes up, melting point also goes up

Question 15

what is the relationship between unsaturation and melting point?

Answer 15

more unsaturated=melting point goes down

Question 16

what is the difference between cis and trans fatty acids?

Answer 16

Question 17

how are trans fats produced?

Answer 17

produced by partial hydrogenation of vegetable oils in the food industry
converts some cis double bonds to the trans configuration

Question 18

why do trans fats have higher melting points

Answer 18

they pack more regularly

Question 19

what does trans fats consumption increase

Answer 19

increases risk of cardiovascular disease

Question 20

nomenclature of unsaturated fatty acids

Answer 20

Question 21

where are branched chain fatty acids found?

Answer 21

present in bacteria and some ruminants (dairy products)

Question 22

which branched fatty acids are present in humans?

Answer 22

very uncommon but we have two
pristanic acid
phytanic acid

Question 23

what reactions do branch fatty acids undergo?

Answer 23

alpha oxidation (peroxisome) instead of beta oxidation (in mitochondrion)

Question 24

what are isoprenoids?

Answer 24

similar to fatty acid with some branching but a different type of molecule

Question 25

what are characteristics of triglycerides

Answer 25

100% hydrophobic
excellent way to package and transport fatty acids
present in many foods

Question 25

structure of triglycerol?

Answer 25

three acyl chains + 1 glycerol