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MCP Unit 7 > Lipid Metabolism > Flashcards

Lipid Metabolism Flashcards

1
Q

Why are NEFA bound to proteins usually?

A
  • Because they are toxic to cells

- Long chain FA are almost always esterified and bound to proteins otherwise they will form toxic micelles

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2
Q

Two sources of NEFA

A
  • From dietary fats via exogenous pathway

- Synthesized via endogenous pathway

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3
Q

Most abundant FA

A

Long chain FAs

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4
Q

Myristic acid

A
  • C14
  • No double bonds
  • 14:0
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5
Q

Palmitic acid

A
  • C16
  • No double bonds
  • 16:0
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6
Q

Palmitoleic acid

A
  • C16
  • One double bond
  • 16:1Δ9
  • 16:1ω-7
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7
Q

Stearic acid

A
  • C18
  • No double bonds
  • 18:0
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8
Q

Oleic acid

A
  • C18
  • One double bond
  • 18:1Δ9
  • 18:1ω-9
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9
Q

Linoleic acid

A
  • C18
  • Two double bonds
  • 18:2Δ9,12
  • 18:2ω-6
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10
Q

Linolenic acid

A
  • C18
  • Three double bonds
  • 18:3Δ9,12,15
  • 18:3ω-3
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11
Q

Arachidonic acid

A
  • C18
  • Four double bonds
  • 20:4Δ5,8,11,14
  • 20:4ω-6
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12
Q

Significance of bile

A
  • Acts as a detergent in TG digestion

- Emulsifies TG and other lipids including fat-soluble vitamins (ADKE)

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13
Q

Lipases

A
  • Hydrolyze ester bonds in TG
  • Lingual and gastric lipases work in mouth and stomach: acidic pH optimum
  • Pancreatic lipase hydrolyzes most TG. Works in small intestine (D and J). Optimum pH around 7.
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14
Q

Colipase

A
  • Allows lipase access to lipid substrates
  • Secreted as inactive precursor by pancreas and activated in duodenum thru the action of trypsin
  • Stabilizes the open position
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15
Q

Pancreatic lipase

A
  • Esterase with optimum pH 7
  • Partial hydrolysis of TG containing long chain FA
  • Preference for 1 and 3 positions
  • Main products and 2-MAG and NEFA
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16
Q

Bile components

A
  • Bile acids (salts)
  • Phosphatidlycholine
  • Cholesterol
17
Q

Mixed micelles

A
  • Formed by bile acids with the nonpolar digestion products (2-MAG and NEFA)
  • Allow translocation across aqueous boundary layer at intestinal wall (absorption)
  • Glycerol backbones oriented toward aqueous phase
18
Q

FATP5

A
  • Fatty Acid Transport Protein 5
  • Major FA transporter in enterocytes
  • Carrier-mediated transport
19
Q

AQP3

A
  • Mediates glycerol transport

- Member of aquaporin family

20
Q

Steatorrhea definition and causes

A
  • Excessively fatty stools
  • Failure of bile production or blockage of bile flow
  • Exocrine pancreas dysfunction or obstruction of pancreatic duct
  • Failure of uptake into intestinal mucosal cells (enterocytes)
21
Q

Chylomicrons

A
  • Lipoprotein particles that are exported into the lymph
  • TG resynthesized from 2-MAG and then packaged into chylos
  • Also contains: cholesterol esters, apolipoprotein B48, phospholipids, and cholesterol
  • Makes serum look milky after a fatty meal
22
Q

Intestinal FA-binding protein

A

-Binds LCFAs once their inside the enterocytes

23
Q

Acyl-CoA synthetase

A
  • Also called thiokinase

- Catalyzes formation of acyl-CoA derivatives of LCFA

24
Q

Acyltransferases

A
  • Transacylases

- Catalyze transfer of 2 LCFA moieties to 2-MAG

25
Q

Site of absorption of SCFAs

A
  • In the colon
  • Some bacteria in the colon produce SCFAs
  • Most secreted in feces
26
Q

Apolipoproteins

A
  • Amphipathic proteins

- Added in mature chylomicrons after being released into the bloodstream

27
Q

Apo-B48

A
  • Principal protein component of nascent chylomicrons

- Added in the intestinal mucosa

28
Q

Lipoprotein lipase

A
  • Chylomicron clearance
  • FAs release from the lipoproteins
  • Located in capillary endothelial walls of various tissues (muscle and adipose especially)
  • Cleavage at all 3 ester bonds
  • Products are glycerol and NEFA
  • Needs C2 to recognize chylomicrons
  • Insulin promotes release of lipoprotein lipase from adipocytes and muscle–increased hydrolysis and uptake–used as fuel or stored

MCP Unit 7 (10 decks)

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