7 - Lipids 1 Flashcards

1
Q

What is a lipid generally?

A
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2
Q

What types of lipids are there most commonly in the body?

A
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3
Q

What is the difference between saturated and unsaturated fatty acids?

A

The omega nomenclature is almost exactly the same as the delta nomenclature, the only differences being: Carbons are counted from the methyl (omega) end instead of the carboxylic acid end. The omega symbol is used instead of the delta symbol.

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4
Q

What is the structure and function of triacyglycerols?

A

*The storage form of lipids
* Obtained from diet or synthesized
* Formed by a process called esterification
*triacylgycerols stored in solid form as fat in adipose tissue

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5
Q

What is the structure and function of phospholipids?

A

Phospholipids have clinical significance with use in liposomes.

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6
Q

What is the structure and function of Cholesterol?

A
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7
Q

Explain the digestion and absorption of fat in detail.

A

Dietary fat is mainly comprised of:
* Triacylglycerol (roughly 90%)
* Cholesterol
* Cholesterol esters
* Phospholipids
* Non-esterified fatty acids * Digestion of triacylglycerol to fatty acids begins in the stomach
and is completed in the small intestine
* Medium- and short-chain fatty acids are directly absorbed into
the portal vein
* Long-chain fatty acids need to be resynthesized to triacylglycerol

Ingested fats forms a large structure called fat globules in the small intestine
* Fat globules limit the action of water-soluble digestive enzymes
* Pancreatic lipase (hydrophilic) breaks down triacylglycerols
* Dietary fats need to be emulsified before digestion.
* Liver produces bile
* Bile includes Bile salts, Phospholipids, Cholesterol, Amino acids, and Steroids.

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8
Q

Where and when is fatty acid synthesis performed?

A
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9
Q

How is fatty acid synthesis performed?

A

Addition of 2 carbons per synthetic cycle. It is a two-stage process: Stage 1: Uses acetyl-CoA to form malonyl-CoA Stage 2: Elongation of the fatty acid chain (Fatty acid synthase)

Synthesis beyond 16 carbons occurs in the endoplasmic reticulum with Palmitic acid (16:0) serves as main substrate
-10 carbons or more
-Unsaturated fatty acids
Fatty acid elongase enzymatic complex
-Similar to fatty acid synthase
-CoA instead of ACP
* Goal: to produce elongation of very-long-chain fatty acids (22-24 carbons)
Chain Desaturation:
Fatty acyl-CoA desaturase enables the addition of double bonds in long-chain fatty acids.

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10
Q

How is Acetyl Co-A transported to the cytosol for fatty acid synthesis?

A

malate shuttle

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11
Q

How are triacyglyercols synthesized and stored in the body?

A

Dietary and endogenous fatty acid are converted to triacylglycerol and mostly
stored in adipose tissue.
* Dietary fatty acid is synthesized into triacylglycerol which is transported by chylomicrons
* Endogenous (De novo process) fatty acid synthesized to triacylglycerol is transported by
Very-low-density lipoprotein (VLDL)
* Production of triacylglycerol requires adding a phosphate group to glycerol and involves phosphatic acid as an intermediate.
* The source of glycerol 3-phosphate in both liver and adipose tissue comes
from glucose metabolism, but adipose tissue lacks glycerol kinase, becoming unable to convert free glycerol

Enzyme: Phosphatidic acid phosphatase forms Diacylglycerol
Enzyme: Diacylglycerol acyltransferase forms triacylglycerol
Endogenous triacylglycerols packed into VLDL
VLDL assembled in the
endoplasmic reticulum and released into blood stream to deliver triacylglycerols to adipose tissue

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12
Q

How are triacylglycerols transported in the body?

A
  • Chylomicrons (dietary fat) and VLDL (endogenous fat) systemically travels to
    deliver triacylglycerol to adipose tissue.
  • Chylomicrons and VLDL are acted upon an enzyme called Lipoprotein Lipase
    (LPL).
  • LPL is synthesized and secreted by the adipose tissue → Insulin regulates this mechanism.
  • Interestingly, skeletal muscle
    has LPL, but insulin inhibits its
    activity.
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13
Q
A
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14
Q
A
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