Posi abs processing of lipids

Question 1

What are the roles of fat?

Answer 1

Energy
Cell membranes
essential fatty acids –> eicosanoids (prostaglandins, thromboxanes)

Question 2

what are Chylomicrons?

Answer 2

Lipids from the diet

Question 3

How do fatty acids arrive at peripheral tissue?

Answer 3

• In chylomicrons or VLDL

- From adipose tissue

Question 4

What is beta-oxidation of fatty acids?

Answer 4

Breaking down of fatty acids - to generate acetyl - coA which enters the citric acid cycle (krebs) and NADH&FADH2 which are used by the electron transport chain

Question 5

Describe the process of beta-oxidation?

Answer 5

1) Fatty acids are converted to fatty acyl coA in the cytosol
2) Go to mitochondria matrix via transporter proteins
(Long chains requires carnitine transporter)
3)Beta oxidation begins - fatty acyl coA undergoes oxidation and hydration - NADH & FADH2 released
4) Forms 1 acetyl which enters kreb cycle
5) Releases NADH, FADH2 - electron transport chain

Question 6

How is beta-oxidation controlled?

Answer 6

Carnitine transport system - inhibited by malonyl coA

Regulation of substrate available

When there is excess acetyl coA produced from fatty acid breakdown, it forms malonyl coA which inhibits the carnitine transport system. High levels of malonyl coA means low levels of fatty acid - so less breakdown.