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Date Submitted: 12/28/2014 01:38 PM
Chapter 27: Fatty Acid Metabolism
* Be able to identify the repeated steps of fatty acid degradation
* Be able to describe ketone bodies and their role in metabolism
* Know how fatty acid are synthesized
* Step 1. Preparatory step: transfer of acetyl CoA from mitochondria to cytoplasm
* Step 2. Activation of acetyl CoA: acetyl CoA converted to malonyl CoA
* Steps 3-7. Fatty acid synthesis. Synthesis occurs on an acyl carrier protein, a molecular scaffold.
* Understand the regulation of fatty acid metabolism
* Fatty acids stored as triacylglycerols in adipose tissue.
* Fatty acids are processed in three stages
* Lipids must be mobilized, in this process triacylglycerols are degraded to fatty acids and glycerol, which are released from the adipose tissue and transported to the energy requiring tissues.
* Then, the fatty acids must be activated and transported into mitochondria for degradation.
* Finally, the fatty acids are broken down in a step by step fashion into acetyl CoaA, which is then processed in the citric acid cycle.
* Triacylglycerols are hydrolyzed by hormone stimulated lipases
* After a night’s fast, glycogen stores are low, however lipids are readily available. How are they mobilized?
* Triacylglycerols are stored in an adipocyte as a lipid droplet, an intracellular compartment surrounded by a single layer of phospholipids and proteins required for fatty acid metabolism.
* Triacylglycerol mobilization and deposition take place on surface of the droplet.
* Triacylglycerol in storage form must be hydrolyzed to yield isolated fatty acids.
* Hormones glucagon and epinephrine trigger 7TM receptors that activate adenylate cyclase. The increased level of cyclic AMP then stimulates protein kinase A, which phosphorylates perilipin and hormone-sensitive lipase.
* Phosphorylation of perilipin:
* Restructures the fat droplet...