Lecture 3- Energy storage (fat) Flashcards

1
Q

lipids are stored as

A

triacylglycerol (TAG)

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2
Q

when are lipids stored as TAG

A

Energy intake in excess of requirement

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3
Q

where are TAGs stored

A

hydrophobic stored in anhydrous form in adipose tissue

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4
Q

TAG is a highly effiecient energy store

A

Energy content per gram twice that of carbohydrate or protein

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5
Q

when are TAGs utilised

A

Utilises in prolonged exercise, stress, starvation, during pregnancy

(under hormonal control)

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6
Q

adipocytes

A
  • 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
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7
Q

overview of dietary TAG metabolism

A
  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)
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8
Q

lipogenesis is

A

fatty acid synthesis

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9
Q

where does lipogenesis occur

A

in the liver

(dietary glucose - source of carbon)

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10
Q

outline lipogenesis

A
  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

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11
Q

comparison of fatty acid synthesis and B oxidation

A
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12
Q

lipolysis

A

fat mobilisation

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13
Q

which hormone stimulates lipolysis

A

Hormone sensitive lipase mobilises fatty acids and glycerol from TAG

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14
Q

glycerol

A

can be utilised as a precursor of glucoseneogensis

glycerol –> glucose

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15
Q

fatty acids

A

beta-oxidation (energy production)

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16
Q

fuel stores in 70kg mann vs 135kg man

A

TAG make sup most weight and most energy content in both