Lecture 3- Energy storage (fat)

Question 1

lipids are stored as

Answer 1

triacylglycerol (TAG)

Question 2

when are lipids stored as TAG

Answer 2

Energy intake in excess of requirement

Question 3

where are TAGs stored

Answer 3

hydrophobic stored in anhydrous form in adipose tissue

Question 4

TAG is a highly effiecient energy store

Answer 4

Energy content per gram twice that of carbohydrate or protein

Question 5

when are TAGs utilised

Answer 5

Utilises in prolonged exercise, stress, starvation, during pregnancy

(under hormonal control)

Question 6

adipocytes

Answer 6

• Around 0.1mm in diameter
• Cells expand as more fat added
• Average adult around 30 billion fat cells weighing 15kg
• Can increase in size x4 on weight gain before dividing and increasing total number of fat cells

Question 7

overview of dietary TAG metabolism

Answer 7

1. In the Small intestine fat (TAG) is converted to fatty acids and glycerol by pancreatic lipase
2. fatty acids and glycerol are absorbed by intestinal epithelial cells and then reform as TAG
3. TAG is transoorted to the lymph on chylomicrons and then into the blood
4. in the blood TAG is either sent for storage (in the adipose) or utilisation (in the tissues–> fatty acid oxidation (energy)

Question 8

lipogenesis is

Answer 8

fatty acid synthesis

Question 9

where does lipogenesis occur

Answer 9

in the liver

(dietary glucose - source of carbon)

Question 10

outline lipogenesis

Answer 10

1. Glucose à pyruvate in cytoplasm’s (glycolysis)
2. Pyruvate enter mitochondria and forms acetyl-CoA and OAA which then condense to form citrate
3. Citrate –> cytoplasm and cleaved back to acetyl-CoA and OAA
4. Acetyl-CoA carboxylase produce malonyl-CoA from acetyl-CoA
5. Fatty acid synthase complex builds fatty acids by sequential addition of 2 carbon units provided by malonylCoA

requires ATP and NADPH

Question 11

comparison of fatty acid synthesis and B oxidation

Answer 11

Question 12

lipolysis

Answer 12

fat mobilisation

Question 13

which hormone stimulates lipolysis

Answer 13

Hormone sensitive lipase mobilises fatty acids and glycerol from TAG

Question 14

glycerol

Answer 14

can be utilised as a precursor of glucoseneogensis

glycerol –> glucose

Question 15

fatty acids

Answer 15

beta-oxidation (energy production)

Question 16

fuel stores in 70kg mann vs 135kg man

Answer 16

TAG make sup most weight and most energy content in both