Lipids I Flashcards
What does the term FAT describe?
triacylglycerols
What enzyme is responsible for introducing unsaturated bonds into a FA?
desaturases
Where can desaturases introduce double bonds?
only in the proximal half of FAs (up to carbon #9)
What FAs are termed ‘essential’?
fatty acids that have their double bond in the distal half of the molecule
Where at FAs degraded?
mitochondrial matrix
FAs up to how many carbons can be diffuse across the mitochondrial membranes?
Up to ten carbons
What is the function of Acyl-CoA Synthetase? Where is Acyl-CoA Synthetase located?
to form Acyl-CoA. Outer mitochondrial membrane.
What are the two functions of Carnitine Palmitoyl Transferase I?
Synthesize acyl-carnitine and bring acyl-carnitine into the periplasmic space.
What is the function of Carnitine Palmitoyl Transferase II?
Bring acyl-carnitine into the mitochondrial matrix and catalyze the formation of Acyl-CoA
What type of bond does Acyl-CoA synthetase hydrolyze for energy?
Pyrophosphate
Disorders in FA degradation often present with which two tenets?
Hypoglycemia and low ketone body levels
What does the splitting of a 5-carbon acyl CoA end in?
Acetyl-CoA and Propionyl-CoA
What enzyme converts cis-double bonds between carbon 3 and 4 into trans double bonds?
enoyl-CoA Isomerase
How does alpha-oxidation differ from beta-oxidation?
alpha-oxidation shortens carbon by one and releases CO2
What are the two ways peroxisomal degradation of FDs differs from beta-oxidation?
- the initial step produces H2O2 (instead of FADH)
2. peroxisomal beta-oxidation preferentially degrades long-chains FAs
Refsum disease is caused by what?
defects in alpha-oxidation of branched chain phytanic acid
What organ system is primarily affected by Refsum disease
neurological disorders
What length of acyl-CoA dehydrogenase is most often seen? WHat does this present with?
MCAD. MCAD presents with non-ketototic hypoglycemia and can be life threatening.
What is the most common peroxisome biogenesis disorder? The metabolism of what if affected?
Zellwegger Syndrome. very long chain fatty acids (24 and 26 carbon atoms).
A defect in what enzyme can lead to acute fatty liver of pregnancy?
LCHAD
What is the purpose of ketone body synthesis?
to effectively distribute acetyl-CoA
What is the significance of HMG-CoA Lyase?
committed step of ketone body synthesis
Where is HMG-CoA Lyase expressed?
Liver and Kidney
What is beta-hydroxybutyrate oxidized to? Where does this occur?
acetoacetate. Outside of the liver and kidney.
