Lipids

Question 0

What do triacylglycerols consist of?

Answer 0

3 fatty acid chains esterified to glycerol

Question 1

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

Answer 1

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

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

Vitamins - ADEK

Question 2

What reaction does glycerol kinase do?

Answer 2

Glycerol -> glycerol phosphate

Occurs in the liver

Question 3

What is lipolysis?

Answer 3

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

Question 4

How are fatty acids transported in the bloodstream

Answer 4

Bound non-covalently to albumin

Question 5

Where are the products of lipolysis transported to?

Answer 5

Fatty acids - tissue

Glycerol - liver

Question 6

Where does beta-oxidation occur?

Answer 6

Mitochondria

Question 7

What must happen to fatty acids before they are oxidised?

Answer 7

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

Question 8

What does the activation of fatty acids require?

Answer 8

ATP

Fatty acyl CoA synthase

Question 9

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

Answer 9

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

Question 10

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

Answer 10

Low exercise tolerance

Large amounts of TAGs in muscle

Question 11

What inhibits FA transport?

Answer 11

Malonyl CoA, an intermediate in fatty acid synthesis

Question 12

What happens in the beta oxidation of fatty acids?

Answer 12

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

Question 13

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

Answer 13

Acetyl CoA

Question 14

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

Answer 14

Coenzyme A

Question 15

What produces acetyl CoA?

Answer 15

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

Question 16

Which lipids cannot be synthesised in the body?

Answer 16

Polyunsaturated fatty acids

Question 17

Where are lipids synthesised?

Answer 17

Liver and some in adipose tissue

Question 18

Name the three ketone bodies produced

Answer 18

Acetone
Acetoacetate
Beta-hydroxbutyrate

Question 19

How are the three ketone bodies synthesised?

Answer 19

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

Question 20

When does the concentration of ketone bodies increase?

Answer 20

Starvation

Untreated type 1 diabetes

Question 21

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

Answer 21

Cholesterol

Reductase

Question 22

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

Answer 22

Ketone bodies

Lyase

Question 23

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

Answer 23

All tissues containing mitochondria - even the CNS

Question 24

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

Answer 24

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