Lipids 3 Flashcards Preview

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Flashcards in Lipids 3 Deck (25):
1

Where does fatty acid synthesis occur?

liver
lactating mammary gland
adipose tissue

2

What are fatty acids synthesised from?

from acetyl CoA derived from excess protein, fat and carbohydrate

3

What part of the cell does fatty acid synthesis occur in?

cytosol

4

Acetyl CoA is formed in the matrix of the mitochondrion and so has to be transferred out into the cytosol. How does this occur?

via the citrate shuttle when citrate concentration in mitochondrion is high

5

What 2 enzymes are required for fatty acid synthesis?

Acetyl CoA carboxylase (activation/regulation)
Fatty acid synthase (multifunctional enzyme)

6

What is required for fatty acid synthesis?

enzymes
acetyl CoA and NADPH

7

What is produced from fatty acid synthesis?

palmitic acid

8

What does acetyl CoA carboxylase do?

forms Malonyl CoA by adding CO2 to acetyl CoA which is the committed step in fatty acid synthesis

9

What are the key regulators of the activity of acetyl CoA carboxylase?

activated by citrate (signals that there is enough glucose)
deactivated by palmitoyl CoA
insulin activates
glucagon and epinephrine deactivate

10

What happens in elongation of malonyl coA?

Acetoacyl-ACP is formed from Acyl-malonyl ACP condensing

11

What is acetoacetyl-ACP?

complex of acyl-malonyl and ACP enzyme

12

What happens to the acetoacyl-ACP?

carbons are added 2 at a time with the enemy acting as an 'arm' sweeping to pick up these carbons. Palmityl-ACP is formed

13

What does thioesterase do?

cleaves palmityl CoA from the ACP

14

What does the multifuctional fatty acid synthase enzyme do?

Works with the ACP to catalyse the formation of long chain fatty acids.
Is a series of 7 enzymes that the ACP arm swings the acyl-malonyl round to catalyse reactions to extend the chain

15

How much NADPH is required for the formation of palmitate and where do we get the NADPH?

14
from the pentose phosphate pathway

16

Where does any extra modification of palmitate or dietary fatty acids occur?

in mitochondria and ER by diverse enzymes

17

What are steroid hormones?

chemical substances that serve as chemical messengers in the body

18

What is the starting material for the formation of steroid hormones?

cholesterol

19

What are eicosanoids?

signalling molecules derived from 20 carbon unsaturated fatty acids (omega 3) and are synthesised throughout the body

20

What is the function of cholesterol?

component of cell membranes
precursor to other substances e.g. sterol hormones, vitamin D, bile acids

21

Where is cholesterol made?

mainly in the liver

22

What do statins do?

inhibit enzyme responsible for cholesterol synthesis and lower LDL levels

23

What do eicosanoids regulate?

inflammatory response
pain and fever
blood pressure
blood clot induction
labour induction
sleep/wake cycle etc

24

What are COX inhibitors?

aspirin
anti-inflammatory and fever-reducing property due to inhibition of COX1 enzyme and prostaglandin synthesis

25

What are eicosanoids precursors to?

prostaglandins, leukotrienes and thromboxanes