Lipds Flashcards

1
Q

Where are lipids found?

A

Lipid droplets in adipose tissue, cell membrane, blood lipoproteins

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2
Q

Functions of lipids

A
  • Stored form of energy
  • Structural element of membranes
  • Enzyme cofactors
  • Steroid Hormones
  • Vitamins A,D,E,K
  • Signalling molecules
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3
Q

Lipid Classes

A
  • Stored form of energy
  • Structural element of membranes
  • Enzyme cofactors
  • Steroid Hormones
  • Vitamins A,D,E,K
  • Signalling molecules
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4
Q

Main dietary lipid

A

Triacylglycerol

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5
Q

What are bile salts?

A

Biological detergents to form emulsions and mixed micelles

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6
Q

Digestion of Triacylglycerol

A

Monoacylglycerol + 2 Fatty Acids

in small intestine by Pancreatic Lipase

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7
Q

Cholesterol Ester digestion

A

Cholesterol & Free fatty acids

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8
Q

Phospholipid digestion

A

Hydrolysed into fatty acids & lysophospholipids

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9
Q

Uptake of digested lipids

A

-Product of lipid digestion + bile salts -> mixed micelles
-Lipid products enter enterocytes via diffusion
(short & medium fatty acids don’t require micelles for diffusion)

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10
Q

What happens to dietary lipids?

A

Lipids are solubilised by apoB-48 into chylomicrons

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10
Q

What happens to dietary lipids?

A

Lipids are solubilised by apoB-48 into chylomicrons

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11
Q

What happens to chylomicrons?

A

Hydrolysed by lipoprotein lipase into fatty acid & glycerol

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12
Q

Release of energy from stored Triacylglycerol

A

Triacylglycerol -> Fatty acids [Hormone Sensitive Lipase]

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13
Q

Lipoprotein classes

A
  • Chylomicrons - TAG rich (carry TAG from intestine to tissue)
  • VLDL - TAG rich (carry TAG from liver to tissue)
  • LDL - Cholesterol rich (cholesterol to extrahepatic tissue [outside liver])
  • HDL - Protein / Cholesterol rich (transport cholesterol from tissue to liver for elimination)
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13
Q

Lipoprotein classes

A
  • Chylomicrons - TAG rich (carry TAG from intestine to tissue)
  • VLDL - TAG rich (carry TAG from liver to tissue)
  • LDL - Cholesterol rich (cholesterol to extrahepatic tissue [outside liver])
  • HDL - Protein / Cholesterol rich (transport cholesterol from tissue to liver for elimination)
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14
Q

How are lipids transported

A

Lipoproteins

15
Q

Steps of Beta-Oxidation

A

(1) Activation of fatty acid in cytosol
(2) Transport into the mitochondria
(3) Degradation of two carbon fragments (as acetyl CoA) in the mitochondrial matrix

16
Q

Transport by Carnitine Shuttle

A
  • Fatty acyl CoA gives CoA to Carnitine [Carnitine Palmitoyl Transferase]
  • Fatty Acyl Carnitine moves into mitochondrial matrix via Carnitine Translocase Molecule
  • Carnitine replaced with CoA
17
Q

Beta-Oxidation Degradation steps

A

(1) Dehydrogenation, produces FADH2
(2) Hydration
(3) Dehydrogenation, produces NADH
(4) Thiolysis (cleaved), produces acetyl CoA

18
Q

Why does Beta-Oxidation occur?

A

Provides energy for skeletal/heart muscle & kidneys when glucose / glycogen / gluconeogenic precursors become scarce

19
Q

Main ketone bodies

A

3-Hydroxybutyrate, Acetoacetate

19
Q

Main ketone bodies

A

3-Hydroxybutyrate, Acetoacetate

20
Q

What uses ketones for energy?

A

Cardiac/ skeletal muscles, kidneys, brain cells

21
Q

Where does Fatty Acid Synthesis occur?

A

Liver, Lactating mammary gland, adipose tissue

22
Q

Requirements for Fatty Acid Synthesis

A
  • Acetyl CoA Carboxylase (activation / regulation)
  • Fatty Acid synthase (multifunctional enzyme)
  • Acetyl CoA
  • NADPH
23
Q

Product of Fatty Acid synthesis

A

Palmitic Acid

24
Q

Overall reaction for palmitate

A

8 Acetyl CoA + 14 NADPH + 14 H+ + 7 ATP

-> Palmitate + 8 CoA + 14 NADP+ +7 ADP + 7 Pi + 7 H2O

25
Q

Fates of Fatty Acids

A
  • Combine with glycerol -> Triacylglycerol

- Triacylglycerol + proteins + phospholipids + cholesterol ester -> VLDL

26
Q

Steroid classes

A
  • Cholesterol
  • Steroid Hormones
  • Bile salts
27
Q

Cholesterol function

A
  • Component of cell membrane

- Precursor to other substances

28
Q

Eicosanoids function

A

Signalling molecules, derived from omega-3 or omega-6 fatty acids