Fat and Protein Metabolism Flashcards
the most energy-dense dietary source
fatty acids
how are fats digested?
- dietary fats are insoluble, so bile is released to emulsify fat particles into dispersed, soluble micelles
- intestinal lipases degrade the fats so they can be absorbed and converted into TAG (triacylglycerols)
- which are then incorporated into chylomicrons
lipoproteins are useful for…examples…
packaging and transporting lipids after they’ve been reconstituted into triacylglycerides in the core of a protein molecule
HDL, LDL, chylomicrons (this holds the triacyglycerides)
apolipoproteins are useful for…
signaling. determine the functional properties of lipoproteins, which express apolipoproteins
apolipoproteins are…
lipoproteins unbound to lipids. vary in their ratios of proteins to lipids.
what makes lipoproteins dense?
the higher ratio of proteins to lipids. this density is what makes lipoproteins function differently
how do the majority of fatty acids enter the outer membrane of the mitochondria?
the majority are too large to freely diffuse into the membrane. energy has to be coupled to bring the fatty acids, by way of carnitine shuttle. carnitine-bound fatty acids enter the outer membrane through an enzyme called transferase
Krebs Cycle produces how much ATP?
remember: per 1 acetyl-CoA, 10 ATP is produced
oxidation of fatty acids produces how many NADH and FADH2?
1 molecule of NADH and 1 molecule of FADH2
a 20 carbon fatty acid yields how many acetyl-CoA’s after how many oxidations?
10 acetyl-CoA’s and 9 passes
ATP per NADH, FADH2
2.5 for NADH, 1.5 for FADH2
what are the major products of amino acid catabolism?
ketone bodies and glucose
- there are two main pathways for amino acid metabolism
- defined by the end products degraded
- one is degraded to acetyl-CoA or acetoacetyl-CoA, the other to pyruvate (ketogenic and glucogenic)
how many amino acids are essential for life?
21 amino acids are used by humans, and 9 are considered essential (meaning we can’t make them ourselves)
Oxaloacetate (OAA)
an important intermediate in the CAC and gluconeogenesis, formed by pyruvate or malate
ketogenic amino acids
metabolized to form acetyl-CoA
glucogenic amino acids
enter the citric acid cycle at different points, with the goal of producing glucose; catabolized to form pyruvate or OAA
fatty acid metabolism
metabolized to form acetyl-CoA, which enters the CAC
three fuels of the human body
- glycogen - way of storing carbohydrates (long chain polymer of glucose molecules attached to each other) stored in liver and muscles (4 kcal/g)
- protein - long chains of amino acids (muscles) (4 kcal/g)
- fats - stored in adipose tissue (9 kcal/g)
triacylglyceride (three main properties)
same as a fat
- inert (non-polar) - not very reactive
- energy-rich - contains many hydrogens
- plays no functional role in the body except energy storage
- hydrophobic - think about glycogen has a lot of water weight, so we’d weigh much more if glycogen was our storage source
lumen
the same that food travels in the small intestine
lipase
an enzyme released by the pancreas and cells lining the small intestines
bile
secreted by the liver, stored in the gallbladder, useful as a detergent to break up fatty globules through emulsification
what does lipase do?
cleaves triacylglycerides (with the addition of water) at the ester linkages; produces a free glycerol backbone and three fatty acids (which are carboxylic acids)
carboxylic acid
draw it out
