Lipids

Question 1

Major types of lipids

Answer 1

Fatty acids
Glycerolipids
 -triglycerides
 -phospholipids
Steroids
Others

Question 2

Lipid structure

Answer 2

Short 4-6C
Medium 4-12C
Long 14-36C

Saturated (no double)
Monounsaturated (one)
Polyunsaturated (two+)

methyl, middle, acid group

9kcal/g

Question 3

Essential Fatty Acids

Answer 3

linoleic (AI: 17/12)

alpha-linolenic (1.6/1.1)

Question 4

Digestion of lipids

Answer 4

emulsification by phospholipid and bile salts,

mouth, lingual lipase?
stomach, gastric lipase (10-30%)

small intestine, duodenum (cholecystokinin), secretin, bile

procolipase (trypsin) colipase+pancreatic lipase active lipase

pancreatic lipase needs to be activated by colipase

triglycerides digested to 2 fatty acids and monoglyceride

ferried to intestinal mucosa by micelles

Question 5

Glycerolipids

Answer 5

Glycerol backbone

Question 6

Hydrogenation

Answer 6

forms trans fats

Question 7

Phospholipids

Answer 7

glycerol backbone
2 FA
phosphate group
N containing group
emulsifiers
membranes

Question 8

Steroids

Answer 8

Cholesterol
Essential
synthesized

Question 9

metabolism of chylomicrons and lipoproteins

Answer 9

1. intestinal lumen to intestinal mucosal cell
2. intestinal mucosal cell to lymph or portal blood
3. short/medium FA into portal and then liver
4. long FA and monoglycerides form triglycerides
5. triglycerides + phospholipids and cholesterol and apoprotein to form chylomicron
   Chlyomicron secreated into lymphatic system

Question 10

lipids after absorption

Answer 10

free cholesterol is esterified by ACAT then added to chylomicron

Question 11

ketosis

Answer 11

FA oxidation exceed availability of CHO intermediates

starvation and diabetes mellitus lead to ketosis

Question 12

Classification of lipoproteins

Answer 12

based on density

chylomicrons
Very low density lipoproteins (VLDL)
LDL
HDL

Question 13

Eicosanoids

Answer 13

20C

hormones

Question 14

Recommendations for fat intake

Answer 14

no RDA

infants AI 30-31