Chapter 17 Flashcards
What are the advantages of using fats over polysaccharides for energy ?
- fatty acids carry more energy per carbon b/c they are more reduced
- they carry less water b/c they are nonpolar
What emulsifies dietary fats in the small intestine, forming mixed micelles
bile salts
What do intestinal lipases degrade triacylglycerols into ?
triacylglycerols are degraded into free fatty acids and monoacylglycerols
What are spherical aggregates of apolipoproteins and lipids ?
lipoprotein particles
What are Chylomicrons
Lipoprotein particles consisting of (main component is apolipoprotein B-48) as well as triacylglycerols, cholesterol and other apoliporoteins
function is to transport lipids from the intestine to adipose tissues
Where are fatty acids converted into triacylglycerols
liver
What two molecules trigger lipases
glucagon and epinephrine
What does serum albumin do?
it is a blood protein that non-covalently binds and transports free fatty acids to target tissues
What are proteins in their lipid free form that eventually bind lipids to form lipoproteins ?
Apolipoproteins
What is the primary protein component of chylomicrons
apolipoprotein B-48
What is the protein picked up from high-density lipoprotein particles by chylomicrons?
Apolipoprotein C-II
Name the family of proteins that coat the surface of lipid droplets to restrict access to lipid droplets
Perilipins
In the metabolism of glycerol, what is glycerol converted to ?
Glyceraldehyde-3-phosphate
Through what enzyme are fatty acids converted into fatty acyl coA ?
via fatty acid acyl coA synthetase
What are fats degraded into in the cytoplasm of adipocytes ?
fatty acids and glycerol
Where does the Beta oxidation of fatty acids occur ?
in the mitochondria
What type of fatty acids can freely diffuse across mitochondrial membranes ?
the less common small (<12 carbon) fatty acids
What type of fatty acids are transported into the mitochondria using a transporter?
large fatty acids (which is most fatty acids)
What is the name of the antiporter that transports larger fatty acids across the mitochondrial membrane ?
Acyl-carnitine / carnitine transporter
What is being shuttled in and out of the acyl-carnitine / carnitine cotransporter ?
Acyl-carnitine in shuttled into the matrix as carnitine is shuttled out
What are the roles of the two different carnitine acyl-transferases (CAT 1 and CAT 2)
CAT 1: catalyzes the transesterification b/w fatty acyl-CoA and carnitine (on the cytosolic side of the outer mitochondrial membrane)
CAT 2: catalyzes the transesterification b/w fatty acyl-carnitine and coA (on the matrix side of inner mitochondrial membrane)
What is the rate-limiting step for the oxidation of fatty acids in the mitochondria ?
carnitine mediated entry
What molecule inhibits CAT 1
malonyl-coA inhibits CAT 1 to prevent simultaneous breakdown/synthesis
When oxaloacetate is depleted, acetyl-coA is converted into what ?
Ketone bodies
Under what circumstances does the accumulation of acetyl-coA accelerate the formation of ketone bodies ?
during starvation and in untreated diabetics
What is ketosis, what is ketoacidosis
ketosis - high levels of ketone bodies in the blood + urine
ketoacidosis - ketosis + acidosis (lowered blood pH)
During peroxisomal oxidation, fats can be oxidized to generate _____?_____
heat
What are the two potential fates of acetyl-coA formed in the liver ?
Acetyl-coA can either be oxidized via the citric acid cycle or converted to ketone bodies that serve as fuels for other tissues
In the metabolism of glycerol, glycerol is converted into what?
glycerol —-> D-Glyceraldehyde-3-phosphate (D-G3P)
What causes the release of glycerol
the action of lipases on TAGs
What are lipases
enzymes that breakdown fats in food
Basic relationship b/w lipid & carbohydrate metabolism?
- acetyl-coA is the linking molecule
- glucose, glycerol and fatty acids all degrade into acetyl-coA
What is the role of **Glycogen Phosphorylase **in glycogenolysis
glycogen phosphorylase breaks the alpha 1-4 linkages by adding Pi to the first carbon, transforming glycogen into glucose-1-phosphate
it keeps going until it reaches 4 glucose away from an alpha 1-6 branch
What is the role of the debranching enzyme in glycogenolysis ?
the debranching enzyme grabs the 3 glucose residues and attaches them to a non-reducing end (transferase activity)
What is the role of phosphoglucomutase in glycogenolysis?
