Mcb 450 Notes

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...