Lipids

Question 1

What is the head and tail of a FA made of

Answer 1

Tail: hydrocarbon
Head: carboxylic acid

Question 2

What are FFA bound to in blood?

Answer 2

Albumins

Question 3

What the difference between Cis and trans bonds

Answer 3

Cis - chains are on the same side while trans bonds are on the opposite

Question 4

Glycerol lipids

Answer 4

• are basically TAGS
• glycerol back bone + ester linkages

Question 5

Fat digestion in the mouth

Answer 5

Released by sublingual salivary gland
And the enzyme released is lingual lipase
Breaks down one bound in triglycerides to produce diglyceride and Fa

Question 6

Descibe the digestion of lipids in the stomach

Answer 6

• lingual lipase is not broken down by the stomach acid
• gastric lipase does a small amount of break down in the stomach

Question 7

Describe the digestion in the small intestine

Answer 7

• CCK initiates release of bile acids in the stomach
• fat turns into emulsified fats
  Pancreatic and intestinal lipase break down triglycerides into monglycerides, glycerol, fatty acids

Question 8

Describe digestion in the large intestine

Answer 8

Cholesterol and some fat get trapped in fibre and get excreted

Question 9

Describe the process of process of lipid emulsification

Answer 9

-Bile acid is released and has affinity for water and fat
- fat is in a place where it is inaccessible to lipase
- bile attaches onto fat to become emulsified in to water which make it more accessible to lipases

Question 10

Lingual lipase

Answer 10

Sn-3

Question 11

Gastric lipase

Answer 11

• medium chain FA
• SN-3

Question 12

Pancreatic lipase

Answer 12

Sn-3 or 1

Question 13

Pancreatic lipase A2

Answer 13

Hydrolzes sn-2 and PC hydrolyzes phophotidycholine and FFA

Question 14

Pancreatic Cholesterol esterase

Answer 14

–non specific esterase
- Fatty acids on cholesterol esters, fatty acids at all positions on TG, PL, esters of fat soluble vitamins.

Question 15

How does absorption occur

Answer 15

• Lipids must cross the unstirred water layer before being absorbed by the enterocyte.
• Mixed micelles are more soluble in the unstirred water layer and easily cross the layer.

Question 16

What are the 2 processes in which lipid can be absorbed into the enterocyte

Answer 16

• Carrier mediated proteins on the brush border membrane
• Passive diffusion

Question 17

Where is the NPC1L1?

Answer 17

It’s a protein in which micelles are transported across the brush border membrane into the enterocyte, it’s also a major sterol transporter

Question 18

How are plant sterols absorbed?

Answer 18

The micelles enter the intro site via the NPC1L1 transporter intro into the enterocyte where it undergoes endosomal sorting and comes out as plant sterols add cholesterol. Then exits the intro site as plant sterols and cholesterol

Question 19

What is the mechanism of action for phytosterols?

Answer 19

Phytosterols help lessen the cholesterol that it is absorbed into the micelles then enterocyte

Question 20

Describe the enterohepatic circulation of bile salts?

Answer 20

When bile salts enter the large intestine, it is absorbed into the portal vein where it sent into liver. In the liver, and then goes to the gallbladder, where it is stored and concentrated for use for later.

Question 21

What are the two processes the enterocyte metabolize lipids?

Answer 21

(I) Monoacylglycerol pathway
(II) Glycerol 3-phosphate pathway

Question 22

Describe the monoacylglycerol pathway?

Answer 22

Once the enterocyte has monoacylglycerol absorbed into it it uses acyltransferase to add on a fatty acid in order to form a tag
Enzymes for this process are found in the endoplasmic reticulum

Question 23

Describe the Glycerol 3-phosphate pathway

Answer 23

This process uses glycerol three phosphate to form a diacylglycerol, and then a tag. It occurs when the Meg is not functioning properly