Podcast
Questions and Answers
What is the end product of TAG hydrolysis by hormone-sensitive lipase?
What is the end product of TAG hydrolysis by hormone-sensitive lipase?
- Free fatty acids and glycerol (correct)
- Acetoacetate and acetone
- Acetyl-CoA and glycerol kinase
- Triacylglycerol
In tissues like the liver and kidney, what is glycerol converted into?
In tissues like the liver and kidney, what is glycerol converted into?
- Triacylglycerol
- Acyl-CoA
- Glycerol 3-phosphate (correct)
- Ketone bodies
What enzyme is responsible for converting FFA to acyl-CoA in adipose tissue?
What enzyme is responsible for converting FFA to acyl-CoA in adipose tissue?
- Hormone-sensitive lipase
- Gluconeogenesis enzyme
- Acyl-CoA synthase (correct)
- Glycerol kinase
When does the accumulation of FFA in plasma occur?
When does the accumulation of FFA in plasma occur?
What is the alternative fuel source for cells during conditions like starvation according to the text?
What is the alternative fuel source for cells during conditions like starvation according to the text?
Which additional functional group do phospholipids have?
Which additional functional group do phospholipids have?
In which group do fatty acids fall in terms of being hydrophilic or hydrophobic?
In which group do fatty acids fall in terms of being hydrophilic or hydrophobic?
What is the predominant lipid found in cell membranes?
What is the predominant lipid found in cell membranes?
Which class of lipids includes glycerophospholipids?
Which class of lipids includes glycerophospholipids?
Which part of phospholipids forms the hydrophobic group?
Which part of phospholipids forms the hydrophobic group?
What is the role of thiolase in the process described?
What is the role of thiolase in the process described?
What is the purpose of the non-enzymatic decarboxylation of acetoacetate to acetone?
What is the purpose of the non-enzymatic decarboxylation of acetoacetate to acetone?
In the context of ketolysis, what is the role of succinyl-CoA?
In the context of ketolysis, what is the role of succinyl-CoA?
What is the primary reason for the production of ketone bodies in individuals with type I diabetes?
What is the primary reason for the production of ketone bodies in individuals with type I diabetes?
What is the role of NADH in the ketolysis process?
What is the role of NADH in the ketolysis process?
What is the significance of the liver constantly synthesizing ketone bodies during fasting?
What is the significance of the liver constantly synthesizing ketone bodies during fasting?
Flashcards
End product of TAG hydrolysis
End product of TAG hydrolysis
Free fatty acids and glycerol
Glycerol conversion (liver/kidney)
Glycerol conversion (liver/kidney)
Glycerol 3-phosphate
FFA to acyl-CoA enzyme (adipose)
FFA to acyl-CoA enzyme (adipose)
Acyl-CoA synthase
Plasma FFA accumulation cause
Plasma FFA accumulation cause
Lipolysis
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Alternative fuel source (starvation)
Alternative fuel source (starvation)
Ketone bodies
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Phospholipid additional group
Phospholipid additional group
Phosphate group
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Fatty acid property
Fatty acid property
Hydrophobic
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Main cell membrane lipid
Main cell membrane lipid
Phospholipids
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Lipid class including glycerophospholipids
Lipid class including glycerophospholipids
Steroids
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Hydrophobic phospholipid part
Hydrophobic phospholipid part
Fatty acids
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Thiolase role in ketone bodies
Thiolase role in ketone bodies
Catalyzes HMG-CoA breakdown
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Acetoacetate decarboxylation purpose
Acetoacetate decarboxylation purpose
Acetone release (diagnostic marker)
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Succinyl-CoA's ketolysis role
Succinyl-CoA's ketolysis role
Provides CoA for conversion.
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Type 1 diabetes ketone production reason
Type 1 diabetes ketone production reason
Glucose unavailability, fat use.
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NADH's role in ketolysis
NADH's role in ketolysis
Produced during 3-hydroxybutyrate oxidation
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Liver's constant ketone synthesis (fasting) reason
Liver's constant ketone synthesis (fasting) reason
Alternative energy source during glucose shortage
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Lipolysis and Re-Esterification
- TAG undergoes hydrolysis by hormone-sensitive lipase to form free-fatty acids (FFA) and glycerol
- Glycerol is transported to liver and kidney, where it is converted to glycerol 3-phosphate by glycerol kinase
- FFA can be reconverted to acyl-CoA by acyl-CoA synthase and re-esterified with glycerol 3-phosphate to form triacylglycerol
- There is a continuous cycle of lipolysis and re-esterification within the tissue
Importance of Carbohydrates
- Carbohydrates are essential for metabolism of fat
- Acetyl-CoA from fatty acid can enter and be oxidized in TCA cycle when carbohydrates are available
Ketogenesis
- Ketogenesis occurs when carbohydrates are unavailable, such as in starvation, fasting, and diabetes mellitus
- Acetyl-CoA formed from fatty acid oxidation is converted into ketone bodies (acetoacetate, 3-hydroxybutyrate, acetone)
- Liver mitochondria convert acetyl-CoA from fatty acid oxidation into ketone bodies
Type I Diabetes Mellitus
- Characterized by ↓ insulin and ↑ glucagon
- Biochemical findings:
- ↑Blood glucose
- ↓Blood pH
- ↓HCO3
- Benedict’s test positive → Glucose
- Rothera’s test positive → Ketone bodies
- Free fatty acids in plasma
- Hepatic output of ketone bodies
- Ketoacidosis: Ketonemia – 90 mg/dl, Keturia – 5000 mg/24hr
- Fruity odour on breath
Phospholipids
- Complex lipids with phosphate as the additional functional group
- Amphipathic molecules with hydrophilic and hydrophobic groups
- Phosphate and nitrogen base (e.g. choline, ethanolamine) forms the hydrophilic group
- Fatty acids form the hydrophobic group
- Predominant lipids of cell membranes (Phospholipid bilayer)
- Two classes of phospholipids: Glycerophospholipids and Sphingophospholipids
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