Lipid Metabolism Flashcards
Title the figure

The structure of a fatty acid

- The methyl group (CH3)
- Omega end

- Variable length
- 2-22 carbon chain

Fatty part
- Fat soluble
- Water insoluble

- Carboxyl group (COOH)
- Water soluble
- Fat insoluble
- Acid part
Conjugated fatty acids
- Polyunsaturated fatty acids
- One pair of double bonds are separated by only one single bond
E.g Conjugated Linoleic acid (CLA)
Trans fatty acids
- Found in ruminant’s milk fat or
- Industrially created by plant oils
- Adverse (LDL cholesterol) effects
Emulsified fats are degraded by…
Pancreatic lipases
Generating FFAs
Pancreatic lipase degrades triacylglycerols at which positions?
- 1 & 3 positions
- Creating 1,2 diacylglycerols and 2-acylglycerols
Phospholipids are degraded at which position?
2 position
- By PLA2 enzyme
- Releasing FFA + Lysophospholipid
Glycerol is converted to…
DHAP

Bile Salts

Small Intestine
Contains hydrolytic enzymes from pancreas

- Triacylglycerols transported through bloodstream
- Via VLDLs

- Triacylglycerols transported through the bloodstream
- Via chylomicrons

Adipose tissue

Fatty acids associated with albumin
Title the figure

Lipid release from adipocytes

ATP → cAMP

Protein Kinase

Triacylglycerol lipase

Glycerol

Fatty acid transporter

Muscle:
- Beta-oxidation
- Citric acid cycle
- Respiratory chain
HSL
Hormone-sensitive lipase
- Splits triglycerides →
- Diglycerides
- Fatty acid
MGL
Monoacylglycerol lipase
- Splits monoglycerides →
- Glycerol
- Fatty acid
Diacylglycerol lipase
Splits diglycerides →
- Monoglycerides
- Fatty acid
Before beta-oxidation…
Fatty acids enter the mitochondrial matrix by facilitated diffusion
- Carnitine-fatty acylcarnitine translocase (CAT-1/CAT-2)
The fate of even-number chains in β-oxidation
Acetyl-CoA production
The fate of odd-number chains in β-oxidation
Propionyl-CoA produced
Title the figure

Energy production from Beta-oxidation of palmitoyl-CoA


Give the end products from palmitoyl-CoA
- 7 FADH2
- 7 NADH
- 8 AcCoA
- = 129 ATPs
Title the figure

Energy gain from lipid metabolism

β-oxidation

8 Acetyl-CoA

Citric acid cycle

NADH, FADH2

Respiratory chain
Electron transfer

2H+ + 1/2O2 → H2O
Fatty cow syndrome
- Syndrome of anorexia + Ketonuria
- With fatty liver
- Occurs in overfat cows at calving
PAP
Phosphatidic acid phosphohydrolase
Role of phosphoglycerides
Membrane constituents
Examples of phosphoglycerides
- Lecithin
- Cephalin
- Inositol phosphatides
General structure of phosphoglycerides
- Glycerol +
- FA +
- Phosphate
Lecithin role
- Emulsifier
- Component of cell membranes
Lecithin contains…
Choline
Cephalins are phosphoglycerides that contain…
Cholamine
Role of inositol phosphatides
- Membrane constituent
- 2nd messenger
Give the structure of myoinositol

Give an example of a plasmogen
Platelet-activating factor (PAF)
Degradation by phospholipases can be observed in…
Snake venom (PLA2)
Main role of sphingolipids
Membrane constituents
- Mainly:
- Nerve cells
- Brain
Give examples of sphingolipids
- Sphingomyelin
- Cerebrosid
- Gangliosid
Composition of sphingomyelin
- No glycerol
- Two alcohols in the middle position
- Occupied by an amine
Galactocerebrosides are found mainly in…
Neuronal cell membranes
Sphingolipids containing several carbohydrates are known as…
Gangliosides
Give identity of the cells: Such as blood group
How is cholesterol transported?
Fatty acids of lecithin
What is the storage form of cholesterol?
Esterified by
- Palmitic acid
- Linoleic acid
Give the primary bile acids produced in the liver
- Cholic acid
- Chenodeoxycholic acid
Deoxycholic acid & lithocholic acid is produced in the…
Intestine
Cholesterol → Chenodeoxycholic acid/cholic acid is catalysed by…
7alpha-hydroxylase
Rate limiting step in bile acid synthesis
Bile acids are used in…
Digestion + absorption of fats + fat-soluble vitamins in the small intestines
Give examples of conjugated cholic acids
- Glycocholic acid
- Taurocholic acid
What is the largest cause of cholesterol breakdown in the body?
Hepatic synthesis of bile acids
Pregnenolone is involved in the synthesis of…
Vitamin A
Steroid hormones are hydroxylated by…
Mixed-function oxygenases/Steroid hydroxylases
Give the two fates of steroid hormone degradation
- Reduction of an unsaturated bond, the introduction of OH groups
- Formation of keto group at C-17
Beta-carotene structure

Fatty acid enters the mitochondrial matrix/IM space in the form of…
Fatty Acyl Carnitine