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31 Cards in this Set
- Front
- Back
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How does glucose and the other monosaccharides get converted to fatty acids?
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DeNovo Synthesis in the liver using aa
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Why is pantothenic acid a critical B-complex vitamin for fatty acid synthesis?
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It is critical because it forms Coenzyme A for Acetyl CoA
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What is the acyl carrier protein?
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Phosphopantetheine
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how is Phosphopantetheine modified to function in fatty acid synthesis and what is its specific role in this process?
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It is linked via a phosphate ester to a serine OH of the Acyl Carrier protein domain
It forms a long flexible are that allows thiol to move from one active site to another within the complex |
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What compound can only be used for fatty acid synthesis and how is this compound formed?
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Malonyl CoAb
Acetyl CoA is carboxylated by ATP dependent carboxylation to provide energy output |
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What is the rate-limiting enzyme for fatty acid synthesis?
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The carboxylation of Biotin, followed by carboxyl transfer from Acetyl CoA is the rate limiting step
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what vitamin does FA synthesis need for activity, how often do we see a deficiency of this vitamin in Americans?
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Biotin is necessary for carboxylation
Deficiency is rare in Americans |
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Inhibition of Acetyl CoA Carboxylase
(FA synthesis) |
Phosphorylation by AMP
Glucagon/Epinephrine inhibit gene expression Palmitoyl CoA via negative feedback to make it a monomer |
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Stimulation of Acetyl CoA Carboxylase?
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Citrate promotes polymerization and forms it from phosphorylated monomers
Insulin activates phosphatase to put it in the most active form and increases gene expression |
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What is the fatty acid synthetase?
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It is a dimer with anti-parallel enzymes that favor inter-subunit transfers
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where is FA Synthetase located and what does it do?
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Multienzyme complex that operates in the cytoplasm
It is uses 7 Malonyl CoA and 1 Acetyl CoA to form Palmitic acid (16:0) |
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What are the 4 steps for fatty acid synthesis:
Condensation |
activated acyl group binds with the CH2 from malonyl CoA releasing CO2
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What are the 4 steps for fatty acid synthesis:
Reduction |
reduction of the beta keto group to an alcohol using NADPH
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What are the 4 steps for fatty acid synthesis:
Dehydration |
elimination of H2O to create a double bond
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What are the 4 steps for fatty acid synthesis:
Reduction |
Reduction of the double bond to create a saturated fatty acyl group using NADPH
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How is fatty acid synthesis via the fatty acid synthetase regulated?
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Stimulated by insulin, Glucose
Inhibited by Polyunsaturated FA and Glucagon |
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how does FA synthesis regulation impact human health?
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Leptin regulates body weight by decreasing food intake, increasing energy expenditure, and inhibiting FA synthesis
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List the 6 enzymes that function in the citrate shuttle?
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ATP citrate Lyase
Malate DH Malic Enzyme Pyruvate Carboxylase Pyruvate DH Citrate Synthase |
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What role does the Citrate Shuttle have in FA synthesis?
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This shuttle is used to transfer pyruvate across the mitochondrial membrane
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List the 3 enzymes that form the NADPH that is needed for fatty acid synthesis?
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Malic Enzyme
Glucose 6-P DH 6-P-gluconate DH |
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How does palmitic acid get elongated to form stearic acid?
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Elongated in 2 carbon steps in the mitochondria (minor) or in the ER (major)
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What are the two essential fatty acids for humans?
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Linoleic Acid (4.44 g/day) and Alpha-Linolenic (2.22 g/day)
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Why are Linoleic and Alpha Linolenic Acid needed in the body?
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Both FA are used to form eicosanoids to regulate metabolic processes in the body
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How do we put double bonds into fatty acids?
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We always add cis double bonds
Done by the Cytochrome Mixed Function Oxidase system in the smooth ER |
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why are the omega-3 fatty acids so important for human health?
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Omega 3 (DHA) is important for brain function and is anti inflammatory
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How is our current diet different from our ancestral diet and what impact has this change in diet had on our health?
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Modern: lower anti-oxidants, bad fats, bad carbs, increased protein and carbs
Ancestral: rich anti-oxidants, good fats, good carbs |
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What is the USDA proposed limit for added sugar per 2,000 Calories per day for the U.S. food label (grams per day)?
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USDA - 8% or 40 grams or 160kcal
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What is the World Health Organizations (WHO) proposed limit for added sugar?
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WHO – recommends that we reduce sugar of all types to 10% of total energy consumption
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Does sugar cause health problems in humans? If it does, what problems does it cause and what are we trying to do about it?
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It causes weight gain, tooth decay, and other health problems
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What has been the single most effective way to prevent childhood obesity?
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Curbing soft drink consumption
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Why are we in the middle of an obesity epidemic in the U.S.?
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Because the levels of consumed carbohydrates is rising
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