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EOM Test 4 > Fatty Acid Metabolism > Flashcards

Fatty Acid Metabolism Flashcards

1
Q

What are three sources of lipid?

A

Fats consumed in the diet

Fats stored in cells as lipid droplets

Fats synthesized in one organ (liver) for transport to another organ

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2
Q

What is the function of acid resistant lingual lipases?

A

Secreted from glands under the tongue

Begins fat digestion in the stomach

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3
Q

What are gastric lipases?

A

Lipases that act in the stomach to digest fats

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4
Q

What is the function of pancreatic lipases?

A

To removie FA at carbons 1 and 3 of triglyceride

*different lipases for each

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5
Q

What is the function of colipase?

A

Anchors pancreatic lipase at the lipid-aqueous interface

Secreted as zymogen

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6
Q

What is the function of Cholesterol esterase?

A

Revmoves FA from cholesterol

Secreted from pancreas

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7
Q

How are phospholipids digested?

A

Phospholipase A2 removes FA from one carbon

Lysophospholipase removes FA at C1

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8
Q

What is the product of phospholipid digestion?

A

Glycerylphosphorylcholine

Exreted, further degraded, or absorbed

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9
Q

What is the function of Cholecystokinin (CCK)?

A

Hormone released from jejunum and duodenum

Acts on Gall bladder to release bile

Acts on pancreas to release enzymes from exocrine cells

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10
Q

What is the function of Secretin?

A

Produced in response to low pH of chyme

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11
Q

What are two consequences of lipid malabsorption?

A

Steatorrhea

Deficiency of lipid soluble vitamins ADEK

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12
Q

What is the function of Apolipoprotein C-II?

A

Activates lipoprotein lipase located on blood vessels

Part of chylomicrons

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13
Q

How are chylomicrons used by tissues?

A

Broken down in capillaries of skeletal muscle or adipose

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14
Q

How are Free fatty acids used by tissues?

A

Fuel or storage or transported to other cells

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15
Q

What is glycerol used for?

A

Used by liver to produce glycerol-3-phosphate for glycolysis or gluconeogenesis

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16
Q

How are chylomicron remnants used by the cell?

A

Endocytosed by liver and hydrolized.

Cholesterol and nitrogenous bases can be recycled

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17
Q

How are triglycerides transported from the lumen to the blood?

A

Broken down in lumen

Re-synthesized within the intestinal cell

TGs are excreted and transported in chylomicrons

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18
Q

What complications of CF are related to fat metabolism?

A

Growth Failure

Bone Disease

Deficiency of fat soluble vitamins

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19
Q

What is medium-chain acyl-CoA dehydrogenase (MCAD) deficiency?

A

Most common genetic defect in FA metabolism in US and Northern Europe

Mutation in enzyme

Causes vomiting, lethargy, hypoketosis, hypoglycemia

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20
Q

What are the three stages of processing for the utilization of fatty acids?

A

Mobilization

Activation and Transport to the mitochondria

Fatty acids broken down into acetyl-CoA

21
Q

How are storage fatty acids signaled to be mobilized?

A

Hormone signalling triggers cAMP/PKA pathway that activates a triacylglycerol lipasae

22
Q

What is the function of Perilipin?

A

Phosphorylated by PKA, increases access to lipids by permeabilizing the lipid droplet

23
Q

What is the function of Fatty acyl-CoA synthetase?

A

Activates Fatty Acids by attaching CoA via ATP hydrolysis

24
Q

What is the function of Carnitine acyltransferase I?

A

Attaches an activated FA to carnitine for transport into the mitochondria

CoA provides the energy for this reaction

25
Q

What type of fatty acids can cross the mitochondrial membrane without carnitine?

A

Short or medium chain fatty acids

<12 C

26
Q

How is carnitine obtained?

A

Meat

Synthesized from lysine and methionine by liver or kidney

27
Q

What is the rate limiting step for FA oxidation?

A

Carnitine transport

28
Q

What inhibits CPT-1?

A

Malonyl CoA

29
Q

What things could result in carnitine deficiency?

A

Liver disease

Malnutrition or vegetarian diet

Increased requirement - burns, pregnancy

Hemodialysis

Congenital deficiency

30
Q

What results from an inability to use LCFA as fuel?

A

Imparied ability to synthesize glucose furing a fast, possible hypoglycemia, coma and death

Impaired ability to sustain exercise

31
Q

What are the three stages of Fatty acid oxidation?

A

Successive removal of two C units

Acetyl groups are oxidized to CO2 in the citric acid cycle

Electrons are donated to the mitochondrial respiratory chain to phosphorylate ADP to ATP

32
Q

What is the order of reactions in fatty acid oxidation?

A

Oxidation–>Hydration–>Oxidation–>Thiolysis

33
Q

What is produced during each round of FA oxidation removing two carbons?

A

1 FADH2 - first oxidation

1 NADH - second oxidation

1 Acetyl CoA - thiolysis reaction

34
Q

How many ATP are formed from complete oxidation of palmitate (C16)?

A

106 ATP

35
Q

What type of fatty acid does B-oxidation completely degrade?

A

Saturated fatty acids with an even number of carbons

36
Q

What are the final products of B-oxidation of odd-number chain fatty acids?

A

Propionyl CoA and Acetyl CoA

37
Q

What is the fate of Proprionyl CoA after B-oxidation?

A

Converted to succinyl CoA to enter the Citric acid cycle

38
Q

What is the function of propionyl CoA carboxylase and what does it require?

A

Forms Methylmalonyl CoA from Propionyl CoA

Requires biotin

39
Q

What does L-methylmalonyl–> succinyl CoA isomerization require?

A

Methylmalonyl CoA Mutase

Derivative of Vit B12 as coenzyme

40
Q

What do unsaturated fatty acids with an odd number of double bonds require?

A

An additional isomerase that converts the cis double bond to a trans double bond

41
Q

What do unsaturated fatty acids with an even number of double bonds require?

A

Reductase and isomerase

42
Q

What is Refsum Disease?

A

Genetic deficiency in the peroxisomal enzyme responsible for one of the initial steps in the oxidation of phytanic acid

43
Q

What are the symptoms of Refsum disease?

A

Retinities Pigmentosa

Progressive peripheral neuropathy

Skeletal malformation

Sever motor weakness

44
Q

Where are very long, or branched chain fatty acids oxidized?

A

Peroxisomes

45
Q

What are the four steps in a-oxidation for branched chains?

A

Activation with CoA

CoA and Formic acid released

Dehydrogenation

Activation with CoA, then B-oxidation releases propional CoA

46
Q

What is Ketosis?

A

Ketone bodies are formed from Acetyl CoA when fat degredation predominates

47
Q

What ketone bodies are formed during ketosis?

A

Acetoacetate

3-hydroxybutyrate

Acetone

48
Q

How is ketogenesis regulated?

A

Entry of FA into oxidative pathway controlled by CPT-1

As level of FFA increases, more FFA converted to ketones

49
Q

How does diabetes cause ketoacidosis?

A

Absence of insulin means liver cannot provide oxaloacetate

Insulin normally decreases fatty acid metabolism

Result is liver produces large amount of ketone bodies which are moderately strong acids

EOM Test 4 (19 decks)

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