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149 Cards in this Set
- Front
- Back
What are the 3 options for glucose-6-phospate to be converted into?
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glycogen, pyruvate, ribose-5-phsophate
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once in the cell, glucose is converted into glucose-6-phosphate. What is good about this as far as metabolism is concerned?
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glucose cannot leave the cell, and therefore will be metabolized.
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What is the main anabolic purpose of the pentose phosphate pathway?
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generation of NADPH for biosynthesis.
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What are the two catabolic functions of the pentose phosphate pathway?
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generation of pentose for nucleotides and the degradation of pentoses from the diet
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What is the net reaction of the pentose phosphate pathway?
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(3 glucose-6-P) + (6 NADP+) + (3 H2O) ---> (6 NADPH) + (6H+) + 3 (CO2) + (2 Fructose-6-P) + (Glyceraldehyde-3-P)
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How many NADPH result (net) from the pentose phosphate pathway?
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6
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What are the two phases of the pentose phosphate pathway?
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oxidative and non-oxidative
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What does NADPH stand for?
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Nicotinamide Adenine Dinucleotide Phosphate
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What is the regulatory step of the pentose phosphate pathway?
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glucose-6-phosphate (alcohol) ---> 6-phosphoglucono-lactone (carboxyilc acid) [oxidation]
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Which enzyme regulate the regulatory step of the pentose phosphate pathway?
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glucose-6-P dehydrogenase
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glucose-6-phosphate dehydrogenase requires --- to function.
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NADP+
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In the second oxidative reaction in the pentose phosphate pathway, the enzyme 6-phophoglucono-lactonase requires ---.
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water (H2O ---> H+)
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What is the second oxidation reaction in the pentose phosphate pathway?
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6-phophoglucono-lactone --> 6-phosphogluconate
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What happens in the third oxidatiive reaction of the pentose phosphate pathway?
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6-phosphogluconate ---> ribulose-5-P (CO2 lost)
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The third oxidative reaction of the pentose phosphate pathway requires which enzyme?
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phophogluconate dehydrogenase
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phosphogluconate dehydrogenase (pentose pathway) requires which molecule?
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NADP+
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The third oxidative reaction in the pentose pathway is a decarboxylation reaction that releases ----, and is therefore ---.
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CO2, irreversable
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The oxidative reactions in the pentose phosphate pathway yield --- NADPH per glucose.
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2
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In the non-oxidative reactions of the pentose phosphate pathway, there are 3 reactions. 2 of them are ---- reactions and 1 is a --- reaction.
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transketolate, transaldolase
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What does a transketolase do?
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transfers a carboxy group- forms glyceraldehyde-3-P, a product of the pentose pathway
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What does transketolase require for function?
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TPP (Vitamin B1, a cofactor)
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What does a transaldolase do?
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moves blocks of carbon between molecules. Prepares molecule in pentose pathway for second transketolase reaction to form fructose-6-phospate, a product of the pentose pathway.
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Ribose-5-phosphate is a metabolite of the pentose phosphate pathway. It also is used in --- biosynthesis.
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nucleotide
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Fructose-6-P and Glyceraldehyde-3-P are a result of the non-oxidation reactions of the pentose phosphate pathway. Where else are they used?
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Glycolysis and TCA cycle
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Essentially, the pentose phosphate pathway converts glucose into 3 things for biological funciton. What are they?
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DNA, NADPH, and intermediate for the citric acid cycle to for ATP
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What is the rate limiting step of the pentose phosphate pathway?
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G-6-P dehydrogenase reaction
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The rate of the pentose pathway is controlled by the availability o the substrate, ----.
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NADP+ (needed for reducing power to NADPH)
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Reactive oxygen species have a strong effect on ---, causing mutations.
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DNA
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Since mitochondria lack DNA repair, they are very susceptible to mutations due to ---.
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reactive oxygen species
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Which enzyme is used in defense of superoxide species?
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superoxide dismutase
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What is a superoxide?
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O2-
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What is a peroxide?
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H2O2
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What is a hydroxyl free radical?
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H2O + .OH
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What are three enzymes used in defense against peroxides?
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peroxidase, catalase, glutathione
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Glutathione functions as an ---
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antioxidant
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GHS refers to reduced gluthathione, a tripeptide of the amino acids ---, ---, and ---. This functions as an antioxidant.
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glycine, glutamate, and cystine
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Someone with G-6-P dehydrogenase defficiency confers resistance to --- because there is too much oxidative stress on the transmititng parasite for it to survive.
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malaria
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Acetyl-CoA is a precursor to --- acids.
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fatty
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Fatty acids are made from the breakdown of excess ---.
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glucose
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Fatty acids are formed from repetitive ---- reactions.
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condensation
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The synthesis of fatty acids requires --- and --- as an energy sources.
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ATP, NADPH
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In animals, where does NADPH production (the pentose phosphate pathway) take place?
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cytosol
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In animals, where does fatty acid synthesis take place?
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cytosol
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In animals, where does acetyl CoA production take place?
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mitochondria
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In animals, acetyle CoA is produced in the mitochondria and is then exported to the cytosol where is can then be converted into a ----.
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fatty acid
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In animals, fatty acids are oxidized in the ---.
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mitochondria
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In plants, NADPH is produced in the ---.
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chloroplast
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In plants, fatty acid synthesis occurs in the ---.
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chloroplast
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In plants, fatty acid oxidation occurs in the ---.
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peroxisome.
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In plants, acetyl CoA is produced in the peroxisome, and is then exported to the chloroplast where it is made into a ---.
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fatty acid
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phospholipid synthesis occurs in the ---.
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endoplasmic reticulum
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What is the rate limiting (or committed) step in fatty acid synthesis?
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acetyl CoA ---> malonyl CoA (once it's malonyl CoA, it can't become anything other than a fatty acid)
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What stimulates the synthesis of malonyl CoA from Acetyl CoA?
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citrate
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What inhibits the synthesis of malonyl-CoA from Acetyl CoA?
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Palitoyl-CoA (the product of the entire pathway)
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What is the product of the pathway to build fatty acids?
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palmitoyl coA
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In the conversion of Acetyl CoA to Malonyl CoA, --- is used as an energy source.
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ATP
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The acyl carrier protein (ACP) can react with acetyl-CoA or Malonyl-CoA to form 2 seperate ---.
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trans-aclases
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The fatty acid synthase complex has -- enzyme activities.
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7
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What is the end product of fatty acid synthesis?
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palmitate (16C)
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Where is pamitate transported to once it is formed?
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endoplasmic reticulum
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Fatty acid chains are elongated by adding -- carbons at a time.
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2
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With each condesation reaction, a fatty acid chain grow by two carbons and also a molecule of --- is released.
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CO2
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Linoleate and alpha linoleate are --- fatty acids.
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essential
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The fatty acid synthase in plants and bacteria has seven activities in --- polypeptides.
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7 seperate
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The fatty acid synthase in yeast has seven activities in --- polypeptides.
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2 separate
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The fatty acid synthase in vertebrates has seven activities in -- polypeptide.
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1 large
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Additional sources of NADPH include reactions that occur in the ---, ----, and --- in animals.
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liver, mammary gland, adipose tissue
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In order to export acetate from within the the mitochondrial matrix into the cytosol, acetyl-CoA must be converted into --- and then transported through the membrane through a specific protein.
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citrate
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The mitochondrial matrix is impermiable to ----.
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acetyl-CoA
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--- triggers the activation of citrate lyase, which causes citrate to from Acetyl-CoA (beginning of FA synthesis)
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insulin
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---- and ----- inhibit acetyl-CoA carboxylase, which causes acetyl-CoA to be converted into Malonyl-CoA (committed step of fatty acid synthesis pathway). These are present in the body during fasting. Palmitoyl-CoA also inhibits this (since it's the final product of FA synthesis)
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glucagon, epinephrine (adreniline)
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Malonyl-CoA inhibits fatty acyl-carnitine, which induces ----.
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beta oxidation
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citrate induced the formation of malonyl coA from ---.
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acetyl CoA
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What are the two regulators for fatty acid synthesis?
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citrate and palmitate
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What is the regulator of fatty acid breakdown?
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insulin
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What type of ACP does fatty acid synthesis require?
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malonyl
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which type of ACP does fatty acid breakdown require?
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acetyl-CoAa
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What is the energy source for fatty acid synthesis?
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NADPH
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Which two oxidizing agents are required in the breakdown of fatty acids?
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NAD+ and FAD
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Where does fatty acid synthesis occur?
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cytoplasm
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Where does fatty acid breakdown occur?
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mitochondria
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What is the basic reaction of fatty acid synthesis in terms of carbon?
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3C + 2C ---> 4C +1C
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What is the basic reaction of fatty acid breakdown in terms of carbon?
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4C ---> 2C + 2C
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Which organ synthesizes sphingolipids?
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brain
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Gangliosides are important molecules in the ---.
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brain
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Excess Acetyl-CoA in the mitochondria often undergo ----.
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ketogenesis
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What are three conditions that promote ketogenesis?
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fasting, diabetes, and a high fat diet
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What are the three "ketone bodies"?
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acetoacetate, beta-hydroxybutyrate, and acetone
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acetoacetate and beta-hydroxybutryate are produced in the liver and act as back up fuel for the generation of ATP when the body doesn't have enough ---.
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glucose.
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ketone bodies are produced in the liver, used by the ---, ----, and ----. They are formed during conditions of excess Acetyl-CoA and low OAA in the TCA.
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heart, kidney, brain
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60 percent of glucose in the body is used by the --.
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brain
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cholesterol is formed from ---.
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acetyl CoA
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synthesis of cholesterol takes place in the ---. (organelle/region)
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cytoplasm
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The major sites of cholesterol synthesis are the ---, ---, ----, and ---.
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liver, intestine, adrenal cortex, and gonads
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All of the carbons in Cholesterol come from ---.
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Acetate
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Pyruvate can be converted into Acetyl CoA and then if it doesn't go the the TCA, can either be converted into ---- or malonyl CoA in order to build fatty acids.
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cholesterol
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All cell types are able to synthesize cholesterol, however the major sites include the liver and small intestine. If they cannot provide adequate supply, then ---- synthesis is activated in other cells.
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DE NOVO (made from recycled parts)
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What is the committed step of cholesterol synthesis?
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HMG-CoA to Mevalonate (required HMG-CoA reductase and 2NADPH)
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What do Statins do? (drug)
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block cholesterol in order to lower choloesterol by compettively inhibiting HMG-CoA reductase (limiting step in cholesterol synthesis)
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Where are the 2 NADPH used in the committed step of cholesterol synthesis made?
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pentose pathway
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In cholesterol synthesis, mevalonate is activated to form ----, which have an active tail and head.
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isoprenes
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In cholesterol synthesis, isoprenes are condensed to form a 15C ---
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chain
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The two 15C chains formed in cholesterol synthesis are then ---- head to head to form a 30C chain.
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condensed
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The pathway to synthesize cholesterol requires A LOT of --- and ----.
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NADPH and ATP
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The final touches of cholesterol synthesis requires this gas in order to get on the endoplasmic reticulum.
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oxygen
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Since cholesterol is toxic to cells in high numbers, it is converted into --- for storage.
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cholesterol ester
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HMG-CoA Reductase is regulated in the endoplasmic reticulum by controlling the transcription of the gene by controlling the gene's ---- region.
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promoter
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what do SREBP and SCAP control?
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The transcription of HMG-CoA Reductase
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Glucagon inhibits/promotes HMG-CoA reductase.
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inhibits
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Insulin inhibits/promotes HMG-CoA reductase.
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promotes
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Cholesterol can be made into ----, -----, or -----.
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steriod hormones, bile acids, or vitamin D
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What are the three things that regulated HMG-CoA Reductase?
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gene transcription, inhibition, and a short half-life
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What do lipoproteins do?
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transport lipids in the blood
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What do chylomycrons do?
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Lipoproteins that transport lipids in the blood to tissues.
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Triglycerides and cholesterold are packaged and transported from the liver to adipose tissue by ---.
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VLDL
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After delivering its contents to the tissues, VLDL is converted first to --- and then into ---, which is taken up by the liver and peripheral tissue cells.
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IDL, LDL
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what is the major carrier of cholesterol in human plasma?
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LDL
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Excess cholesterol from tissues is carried back to the liver by ---.
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HDL
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LDL carries bad cholesterol and HDL carries --- cholesterol.
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good
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Where is VLDL made?
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Liver
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Chylomicrons ---> VLDL ----> ? ---> LDL ----> HDL (largest to smallest, least dense to most dense)
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IDL
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Plasma lipoprotein is in a sphere shape. It has a greasy inside full of triacylglycerols and cholesterol esters, and a polar outsides made of free ---.
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cholesterol
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cholesterol is amphipathic/non polar.
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amphipathic
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cholesterol ester is amphipathic/non polar.
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non polar
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The LDL receptor is a transmembrane receptor with -- different function domains.
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5
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The LDL receptor performs ------- to bring particles into the cell.
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receptor-mediated endocytosis
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Endosomes fuse to liposomes that then digest lipoprotein for cell activation at the ----.
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LDL receptor
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The LDL receptor engulfs larger -- particles and pulls them into the cell.
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fat
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Bioacids are made from cholesterol in the liver and are then repackaged into ----.
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chylomicrons
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After reverse cholesterol transport occurs and HDL transports excess cholesterol back to the liver, this excess cholesterol is sometimes --- as bile acids and cholesterol.
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excreted
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Lipoprotein lipases reside in capillaries waiting for chylomicrons so that they can break them down into ---- for adipose and muscle tissues.
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free fatty acids
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VDL can be converted into --- or fatty acids.
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IDL
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IDL can be converted into ---, fatty acids, or be taken back to the liver.
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LDL
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LDL can be converted into --- or be taken back to the liver.
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fatty acids
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In familial hypercholesterolemia, the liver cannot take up --- or --- from the blood due to a defective receptor, and therefore the individual suffers from high levels of plasma cholesterol.
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IDL or LDL
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What does cholestyramina do to treat high cholesterol levels?
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enhances reverse cholesterol transport
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Statins (such as lipitor) decrease --- levels.
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LDL
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The phospholipid cascade leads to the generation of DAG and IP3, which are intracellular second ---.
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messengers
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Diacylglycerol (DAG) is an endogenous activator of ----.
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protien kinase C
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Inositol triphosphate (IP3) causes a release of a 3rd messengers, ----, from intracellular stores.
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Ca2+
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Steroid hormones produces most of their effects by inducing the ---- of tissue-specifc genes.
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transcription
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What is the term for the 20 carbon unsaturated fatty acids derived from arachidonic acid which make up a class of hormone-like biomodulator substances?
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eicosanoids
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IP3 is formed from the receptor-triggered hydrolysis of ---. (with PLC as a catalyst)
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PIP2
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In the phopholipid cascade, a hormone binds to its receptor, causing the release of GTP. GTP then binds to PLC, which cleaves PIP2 into IP3. IP3 then binds to a receptor on the Ca2+ channel, which causes Ca2+ to move into the cytoplasm. This actives -----, and causes a biological repsonse.
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phosphokinase C
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What does IP3 do in the phopholipid cascade?
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binds to Ca2+ channel on the ER, which causes Ca2+ to build up in the cell
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steroid hormones are all made from --- by removing its side chains and converting it into progesterone.
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cholesterol
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RU 486 is an antagonist for which hormone?
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progesterone (found the in the placenta); also a precursor to many other hormones
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steroid hormone receptors are proteins which are not on the cell surface, but rather found --- the cell.
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within
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What is the zinc binding motif?
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zinc binds to DNA and activates a receptor for steroid hormones
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