Download Metabolism of Glycerol

Lecture Presentation
Chapter 24
Metabolic
Pathways for
Lipids and
Amino Acids
Karen C. Timberlake
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chapter 24 Metabolic Pathways for Lipids
and Amino Acids
Patients diagnosed with
chronic hepatitis C virus (HCV)
infection require lifelong
monitoring by a specialist team
including a public health nurse.
A public health nurse works in
public health departments,
correctional facilities,
occupational health facilities,
schools, and organizations that
aim to improve health at the
community level.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Chapter 24 Readiness
Core Chemistry Skills
• Identifying Fatty Acids (17.2)
• Drawing the Zwitterion for an Amino Acid (19.1)
• Identifying Important Coenzymes in Metabolism (22.3)
• Identifying the Compounds in Glycolysis (22.4)
• Identifying the Compounds and Enzymes in
Glycogenesis and Glycogenolysis (22.6)
• Describing the Reactions in the Citric Acid Cycle (23.1)
• Calculating the ATP Produced from Glucose (23.3)
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
24.1 Digestion of Triacylglycerols
The fat cells (adipocytes) that make up adipose tissue are
capable of storing unlimited quantities of triacylglycerols.
Adipose tissue (made of adipocytes) stores 85% of the total
energy available in the body.
Learning Goal Describe the sites of and products obtained
from the digestion of triacylglycerols.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Digestion of Triacylglycerols
In the digestion of fats (triacylglycerols),
• bile salts break fat globules into smaller particles called
micelles in the small intestine.
• pancreatic lipases hydrolyze ester bonds to form
monoacylglycerols and fatty acids, which recombine in the
intestinal lining.
• phospholipids and proteins coat the fats, forming
chylomicrons, which are transported to the cells of heart,
muscle, and adipose tissues.
• lipases hydrolyze triacylglycerols, forming glycerol and free
fatty acids, which are oxidized to acetyl CoA molecules for
ATP synthesis.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Digestion of Triacylglycerols
The digestion of fats begins in the small intestine when bile
salts emulsify fats that undergo hydrolysis to
monoacylglycerols and fatty acids.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Utilization of Fat
When blood glucose is depleted and glycogen stores are low,
• the process of fat utilization is stimulated.
• the hormones glucagon or epinephrine are secreted into
the bloodstream, where they bind to receptors on the
membrane of adipose tissue.
• a hormone-sensitive lipase within the fat cells catalyzes
the hydrolysis of triacylglycerols to glycerol and free
fatty acids.
• glycerol and fatty acids diffuse into the bloodstream and
bind with plasma proteins to be transported to the tissues,
muscles, and fat cells.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Metabolism of Glycerol
Glycerol from fat digestion
• adds a phosphate from ATP to form
glycerol-3-phosphate.
• undergoes oxidation of the —OH group to
dihydroxyacetone phosphate.
• becomes an intermediate in glycolysis and
gluconeogenesis.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Metabolism of Glycerol
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Study Check
Give answers for the following questions about fat digestion:
1. What is the function of bile salts in fat digestion?
2. How is glycerol utilized?
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.
Solution
Give answers for the following questions about fat digestion:
1. What is the function of bile salts in fat digestion?
Bile salts break down fat globules, allowing
pancreatic lipases to hydrolyze the triacylglycerol.
2. How is glycerol utilized?
Glycerol adds a phosphate and is oxidized to an
intermediate of the glycolysis and gluconeogenesis
pathways.
General, Organic, and Biological Chemistry: Structures of Life, 5/e
Karen C. Timberlake
© 2016 Pearson Education, Inc.