Notes in L24 - Fatty Acid Metabolism

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Published	11/02/2024	While most fats must form micelles to facilitate adequate absorption, fatty acids with fewer than {{c1::12}} carbons can diffuse directly across the w…
Published	11/02/2024	The accumulation of citrate in the cytosol is due primarily to the inhibition of {{c1::isocitrate dehydrogenase}} due to elevated levels of {{c1::ATP/…
Published	11/02/2024	In stage 2, once in the cytosol, citrate is cleaved to {{c1::oxaloacetate and acetyl-CoA}} by {{c1::ATP citrate lyase}} (which promotes fatty acid syn…
Published	11/02/2024	Can CoA bound molecules cross the inner mitochondrial membrane?{{c1::No}}
Published	11/02/2024	Stage 3:In the rate limiting step of fatty acid synthesis, {{c1::acetyl-CoA}} is converted to {{c1::malonyl-CoA}} via the enzyme {{c1::acetyl-CoA carb…
Published	11/02/2024	Where does ketogenesis occur?{{c1::in the mitochondrial matrix of the liver ONLY}}
Published	11/02/2024	Where does fatty acid synthesis occur?{{c1::In the cytosol}}
Published	11/02/2024	Stage 4:Several molecules of malonyl-CoA are assembled by {{c1::fatty acid synthase (palmitate synthase)}} to form {{c1::palmitoyl-CoA}} with {{c1::NA…
Published	11/02/2024	{{c1::Palmitate}} is the only de novo synthesized fatty acid in humans. It is {{c1::16}} carbons in length
Published	11/02/2024	Acetyl-CoA carboxylase is a polymeric enzyme assembled when in the {{c1::dephosphorylated}} state. Phosphorylation, mediated by {{c1::AMPK/PKA}}, caus…
Published	11/02/2024	In states of prolonged starvation, acetly-CoA carboxylase and fatty acid synthase expression {{c1::decrease}}
Published	11/02/2024	Triacylglycerides in adipose tissue are enveloped in a sheath of {{c1::dephosphorylated perilipin}} to prevent lipolysis
Published	11/02/2024	In the fasting state, perilipin in adipocytes is {{c1::phosphorylated by PKA}} causing it to {{c1::release adipose triglyceride lipase, its cofactor C…
Published	11/02/2024	The following lipases can be found in adipocytes:{{c1::Adipose triglyceride}} lipase (along with its cofactor {{c1::CGI-58}}){{c1::Hormone-sensitive}}…
Published	11/02/2024	In the well fed state, Adipose triglyceride lipase and its cofactor CGI-58 are {{c1::bound to perilipin}} and {{c1::inactive}}Hormone sensitive l…
Published	11/02/2024	Free fatty acids are transported in blood bound to {{c1::albumin}}
Published	11/02/2024	In the first step of fatty-acid liver catabolism, fatty acids are converted to {{c1::fatty-acyl-CoA}} via {{c1::acyl-CoA synthetase}} requiring {{c1::…
Published	11/02/2024	While in the {{c1::intermembranous space}} of the mitochondria, fatty-acyl-CoA is converted to {{c1::fatty-acyl-carnitine}} via the enzyme {{c1::carni…
Published	11/02/2024	Once inside the mitochondrial matrix, fatty-acyl-carnitine is converted {{c1::back to fatty-acyl-CoA}} by the enzyme {{c1::carnitine palmatoyl transfe…
Published	11/02/2024	Do all fats require carnitine to enter the mitochondria?{{c1::no}}
Published	11/02/2024	Fatty acid β-oxidation refers to the sequential shortening of fatty-acyl-CoA by {{c1::2}} carbons. Each cycle of β-oxidation yields {{c1::1 acetyl-CoA…
Published	11/02/2024	MCAD (medium-chain fatty acyl CoA dehydrogenase) deficiency.Inheritance pattern: {{c1::autosomal recessive}} Deficient enzyme: {{c1::8-10 carbon …
Published	11/02/2024	What enzyme(s) is/are responsible for β-oxidation?{{c1::fatty-acyl-CoA dehydrogenases specific to various fatty acid lengths}}
Published	11/02/2024	Ketone bodies are used primarily by the {{c1::brain}}, {{c1::muscle tissue}}, and {{c1::kidneys}}. They are never used by the {{c1::liver}} or by {{c1…
Published	11/02/2024	Acetoacetate can be either reduced to {{c1::β-hydroxybutyrate}} via {{c1::β-hydroxybutyrate dehydrogenase}} with {{c1::NADH}} as a cofactor or spontan…
Published	11/02/2024	Which amino acids are purely ketogenic?{{c1::leucine and lysine}}
Published	11/02/2024	What is the rate limiting step of fatty acid synthesis?{{c1::acetyl CoA carboxylase}}
Published	11/02/2024	in stage 1 of fatty acid synthesis, high {{c1::ATP}} levels inhibit {{c1::isocitrate-dehydrogenase}}, resulting in a buildup of {{c2::citrate}} and {{…
Published	11/02/2024	there are 2 "pools" of CoA in the {{c1::inner mitochondrial membrane}} and in the {{c1::matrix}}
Published	11/02/2024	the production of palmitate has 2 steps:priming step: high levels of cytosolic {{c1::Acetyl-CoA}} promote {{c1::Acetyl-coA binding to FAS}}then, {{c1:…
Published	11/02/2024	each malonyl-CoA used by fatty acid synthase (FAS) increases the length of the growing fatty acid by {{c1::2}} carbons
Published	11/02/2024	Acetyl-CoA Carboxylase is a polymeric enzyme that is active in the {{c1::polymerized}} state and inactive in the {{c1::depolymerized}} state
Published	11/02/2024	insulin activates phosphatase 2A (PP2A), which promotes {{c1::polymerization}} of ACC, thus {{c1::activating}} it
Published	11/02/2024	long term regulation of fatty acid synthesis is mediated through induction/inhibition of {{c1::expression of the gene coding for ACC}}
Published	11/02/2024	Human cells possess {{c1::desaturase}} enzymes that can introduce cis-double bonds at carbons 4, 5, 6, and 9 of fatty acids
Published	11/02/2024	human cells lack the ability to introduce double bonds beyond the carbon-{{c1::9}} position
Published	11/02/2024	Linoleic acid [18:2(9,12)] is desaturated and elongated to produce {{c1::arachidonic acid}}, an ω-6 fatty acid
Published	11/02/2024	α-Linolenic acid [18:3(9,12,15)] is desaturated and elongated to produce {{c1::eicosapentaenoic acid (EPA)}} and {{c1::docosahexaenoic acid (DHA)}}, b…
Published	11/02/2024	epinephrine stimulates {{c1::PKA}} in adipocytes leading to {{c1::release of fatty acids}}
Published	11/02/2024	{{c1::carnitine}} acts as a carrier to bring long chain fatty acids into the mitochondrial matrix
Published	11/02/2024	CPTI is inhibited by rising levels of {{c1::malonyl-CoA}}
Published	11/02/2024	carnitine deficiency results from defects in {{c1::transporters}} that allow for uptake of carnitine into cells, causing {{c1::increased storage}} of …
Published	11/02/2024	ketogenesis occurs during {{c1::extended fasting/starvation}} and involves the conversion of {{c1::acetyl-CoA}} to ketone bodies
Published	11/02/2024	high levels of ketone body production cna lead to acetone being expelled on the breath, which has a {{c1::fruity}} odor
Published	11/02/2024	{{c1::HMG-CoA synthase}} catalyzes the rate-limiting step in ketone body synthesis
Published	11/02/2024	in ketolysis, {{c1::β-hydroxybutyrate}} and {{c1::acetoacetate}} are transported into the mitochondrial matrix, where they are converted back to {{c1:…
Published	11/02/2024	{{c1::thiophorase}} is necessary in extra-hepatic tissues to break down ketone bodies and convert them into acetyl-CoA
Published	11/02/2024	thiophorase is not expressed in the {{c1::liver}}, meaning that the {{c1::liver}} can synthesize ketone bodies but not utilize them for energy
Published	11/02/2024	benefits of ketone body production:{{c1::- ketone bodies are soluble and do not need specialized transport mechanisms- they are a useful source of ene…
Published	11/02/2024	{{c1::ketoacidosis}} occurs when excessive production of ketone bodies lower blood pH, resulting in {{c1::dehydration}} as the kidneys increase urinar…
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