Lipids Flashcards Preview

Lizzie's Metabolism > Lipids > Flashcards

Flashcards in Lipids Deck (25):
0

What are the three classes of lipids and what is in each one?

Fatty acid derivatives - fatty acids, triacylglycerols, phospholipids, eicosanoids

Hydroxymethylglutaric derivatives - ketone bodies, cholesterol, cholesterol esters, bile acids and salts

Vitamins - ADEK

1

What do triacylglycerols consist of?

3 fatty acid chains esterified to glycerol

2

What reaction does glycerol kinase do?

Glycerol -> glycerol phosphate
Occurs in the liver

3

What is lipolysis?

When triacylglycerols in adipose tissue are hydrolysed by hormone-sensitive lipase to produce fatty acids and glycerol

4

How are fatty acids transported in the bloodstream

Bound non-covalently to albumin

5

Where are the products of lipolysis transported to?

Fatty acids - tissue
Glycerol - liver

6

Where does beta-oxidation occur?

Mitochondria

7

What must happen to fatty acids before they are oxidised?

Need to be activated.
Bonded to coenzyme A via the S atom in the coenzyme
Forms a high energy hydrolysis bond.

8

What does the activation of fatty acids require?

ATP
Fatty acyl CoA synthase

9

Where is fatty acid oxidation done and what are the consequences of this?

Outside the mitochondrion
Shuttled in via cartinine
Can be used to control the rate of FA oxidation and their entry into the mitochondrion

10

What are the consequence of a defective mitochondrial fatty acid transport system for a patient?

Low exercise tolerance
Large amounts of TAGs in muscle

11

What inhibits FA transport?

Malonyl CoA, an intermediate in fatty acid synthesis

12

What happens in the beta oxidation of fatty acids?

Sequence of reactions that oxidise the FAs and removes a C2 unit each time
Cycle repeats until two C atoms remain

13

In beta oxidation, what are the C atoms which are removed converted into?

Acetyl CoA

14

What are all the intermediates in the beta oxidation pathway linked to?

Coenzyme A

15

What produces acetyl CoA?

Catabolism of fatty acids, sugars, alcohol, and certain amino acids. Also an intermediate in lipid biosynthesis

16

Which lipids cannot be synthesised in the body?

Polyunsaturated fatty acids

17

Where are lipids synthesised?

Liver and some in adipose tissue

18

Name the three ketone bodies produced

Acetone
Acetoacetate
Beta-hydroxbutyrate

19

How are the three ketone bodies synthesised?

Acetoacetate and beta-hydroxybutyrate are produced in the liver from acetyl CoA
Acetone arises from spontaneous decarboxylation of acetoacetate

20

When does the concentration of ketone bodies increase?

Starvation
Untreated type 1 diabetes

21

When insulin levels are high and glucagon is low, what is acetyl CoA converted into and by which enzyme?

Cholesterol
Reductase

22

When insulin is low and glucagon is high, what is acetyl CoA converted into and by which enzyme?

Ketone bodies
Lyase

23

By which tissues can ketone bodies be used as an energy source?

All tissues containing mitochondria - even the CNS

24

When being used for energy, what happens to the ketone bodies?

Converted to acetyl CoA and this goes through stage 3 catabolism (Krebs Cycle)