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Fat Catabolism Chapter 17

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Chapter 17. Fat Catabolism. Fatty Acid Catabolism. Key topics : To Know. How fats are digested in animals How fats are mobilized and transported in tissues How fats are oxidized as a source of energy How “ketone bodies” are produced and used. - PowerPoint PPT Presentation

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Page 1: Chapter 17

Fat Catabolism

Chapter 17

Page 2: Chapter 17

Fatty Acid Catabolism

– How fats are digested in animals– How fats are mobilized and transported in tissues– How fats are oxidized as a source of energy– How “ketone bodies” are produced and used

Key topics: To Know

Page 3: Chapter 17

Oxidation of fatty acids is a major energy source in many organisms

• About one-third of our energy needs comes from dietary triacylglycerols

• About 80% of energy needs of mammalian heart and liver are met by oxidation of fatty acids

• Many hibernating animals, such as grizzly bears, rely almost exclusively on fats as their source of energy

• Some animals (camels) store fat as an eventual source of water

Page 4: Chapter 17

Fats provide efficient fuel storage

• The advantage of fats over polysaccharides:– Fatty acids carry more energy per carbon because they

are more reduced– Fatty acids carry less water along because they are

nonpolar

• Glucose and glycogen are for short-term energy needs, quick delivery

• Fats are for long-term (months) energy needs, good storage, slow delivery

Page 5: Chapter 17

Fat Storage in White Adipose Tissue

Page 6: Chapter 17

Lipid Digestion

Page 7: Chapter 17

Chylomicron

Page 8: Chapter 17

Mobilization of Fat from Adipose Tissue

Page 9: Chapter 17

Guinea Pig Adipocytes

Page 10: Chapter 17

Entry of Glycerol into Glycolysis

Page 11: Chapter 17

Energetics of Glycerol as An Energy Source

Glycerol kinase - ATPGlycerol-3-P DH + NADH3-P-Gyld DH + NADH3-PGA Kinase + ATPPyr Kinase + ATPTotal = 1 ATP + 2 NADH

Can GLYCEROL be FERMENTED? Explain

Page 12: Chapter 17
Page 13: Chapter 17

Major Fatty Acid Oxidation = β-Oxidation Occurs in the Mitochondrion

Page 14: Chapter 17

β-OxidationOverall Flow

Page 15: Chapter 17

One Round (a) and Further Rounds (b) of β-Oxidation

EOC Problem 4: explores numbers of round of β-oxidation.

EOC Problem 9: Compartmentalization of β-oxidation.

Page 16: Chapter 17
Page 17: Chapter 17
Page 18: Chapter 17

EOC Problem 3 Compares β-oxidation with the Citric Acid Cycle

Page 19: Chapter 17

Hibernating Animals Rely upon β-Oxidation for their Sleep

EOC Problems 13, 26 and 28: Deals with Fat as Storage of Water and Energy. Please keep in mind Prof

Makemson spent a good portion of his life in the Middle East…fat as storage of water!!

Page 20: Chapter 17

*Assumes 1 NADH = 2.5 ATP, and 1 FADH2 = 1.5 ATP from Respiratory Electron Transport

Energetics of Oxidation of Palmitic Acid

EOC Problems 1 and 2 deals with amount of energy stored in fat and how long it can last?

Page 21: Chapter 17

Oxidation of Unsaturated Fatty Acids (Remember they are cis!)

Page 22: Chapter 17

Multiple points of unsaturation can require

energy to get them through β-Oxidation

Page 23: Chapter 17

β-Oxidation of Odd Numbered Fatty Acids Results in Propionyl-SCoA

Page 24: Chapter 17

Peroxisomes in Animals – mainly different in First Step and Usually use >20 C and branched chain fatty acids.

Peroxisomes in Plants are main fatty acid oxidation (not in mitochondria)

Plant vs Animal β Oxidation

Page 25: Chapter 17

Seeds are Loaded with Fats and Oils

Page 26: Chapter 17

Arrangement of the β-Oxidation Enzymes

Page 27: Chapter 17

Eukaryotes Also have 2 Arrangements of these Enzymes

Page 28: Chapter 17

ω-Oxidation in the ER of Liver Cells

ω = Omega, the last letter in the Greek alphabet

Minor pathway in mammals, more important in invertebrates

Page 29: Chapter 17

α-Oxidation of Branched Chain Fatty Acids Takes Place in Peroxisomes

Page 30: Chapter 17

β-oxidation of Odd Numbered Fatty Acids … last round produces 1 Ac-SCoA and 1 Propionyl-SCoA

Page 31: Chapter 17

Formation of Ketone Bodies Occurs in the Liver

Isoprenes and Steroids

Page 32: Chapter 17

Oxidation of Ketone Bodies by Non-hepatic Tissues

Page 33: Chapter 17

Requires Glucogenic Intermediates, Glucose can not be made from Ac-SCoA

EOC Problem 16: About use of fatty acids in Diabetics.

Page 34: Chapter 17

Things to Know and Do Before Class1. Review structure of fat, general concepts of

digestion of fat.2. Role of glucagon to mobilize fat utilization.3. Activation of fatty acids in cytoplasm for their

oxidation in the mitochondrion.4. Know the steps of β-oxidation…and what is

involved for the complete oxidation of the fatty acids to CO2 and water.

5. Know that unsaturated fatty acids are oxidized, but energy output is different (which way?).

6. Know that other forms of fatty acid oxidation exist.

7. Know how ketone bodies are made and used.8. EOC Problems: 1-4, 9, 10, 13, 16, 26, 28.