Lipids

Question 1

Define Fat and oil

Answer 1

Fat= solid at RT

Oil=liquid at RT

Question 2

What is TAG?

Answer 2

Triacylglycerol

Question 3

Describe the structure of lipids

Answer 3

Three fatty acids ester linked to glycerol backbone, the 2nd fatty acid is on the other side to the 1st and 3rd

Question 4

Describe the structure of fatty acids

Answer 4

Long chain 12-24 C in hydrocarbon. A CH3 at one end and COOH at the other.

Question 5

What are cis and trans fatty acids?

What angles are they?

Answer 5

Cis- double bond = 120 degrees

Trans - straight = 110 degrees

Question 6

What are the 3 names for fatty acids. using examples

Answer 6

Common name- Oleic acid (oleate)
Systematic name- cis-Δ9-Octadecenoic acid

Omega or n system- C18:1(n-9)

Question 7

Break down the meaning of this name.

C18:2 (n-6)

Answer 7

1= CH3
18= COO-

2= no of double bonds
6= position of first double bond

Question 8

Define elongases

Answer 8

increase chain length by 2C

Question 9

Define desaturases

Answer 9

adds double bonds

Question 10

What is EFA

Why are they given this name?

Answer 10

Essential fatty acids

Humans dont have desaturases to add double bonds lower than omega 9. So omega 3 and 6 have to come from the diet

Question 11

What is the main reasons fatty acids are altered?

Answer 11

For membrane phospholipids

Question 12

What breaks down triglycerides?

And where?

Answer 12

Digested by pancreatic lipases

Question 13

How are digested triglycerides re esterified and where?

Answer 13

In gut mucosa,

First activated by CoA-SH + ATP-> Acyl-CoA +H2O + AMP +PPi
w/ Acyl CoA synthase

2 Acyl-CoA + 2 FA with 2OH -> Triglyceride + 2CoA-SH
w/ acyltransferase

Question 14

What is the composition of lipoprotein

Answer 14

A mixture of lipid and protein
Phospholipid and chol outer layer
Triglyceride and chol
ester core

Question 15

What is the role of the lipoprotein?

Answer 15

Transport from gut to
tissues uses chylomicrons
(up to 1μm in diameter)

Question 16

Describe the uptake into adipose tissue

Answer 16

Endothelial cells have Lipoprotein Lipase attached on the lumenal side
Lipoprotein Lipase cleaves off fatty acids which enter cells
When chylomicron has offloaded most of the TG it is called
a remnant and is removed from circulation by the liver

Question 17

Describe the steps of triglyceride synthesis in adipose tissue or liver

Answer 17

Glycerol-3-phosphate + 3 x activated FA

G-3-P -> DHAP w/ G-3P dehydrogenase and Nad+ to NADH + H+

THEN G3P + CoA-CO-> Lysophosphatidic + CoA-H
w/ G3P acyltransferase

THEN Lysophosphatidic -> phosphatidic acid + CoA-H
w/ 1-acylG-3-P
acyltransferase

THEN Phosphatidic-> Diaacylglycerol +Pi
w/ phosphatidic acid phosphatase

THEN Diacylglycerol-> diglycerol w/ diacylglycerol acyltransferases