Final Flashcards
101 Cards in this Set
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Glycolysis
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Main purpose:
-degrades glucose to generate ATP.
-Provides carbon precursors for biosynthesis.
-Most important control site:
PFK-1
PFK-2 and FBP-2
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Citric Acid Cycle/ ET/Oxidative Phosphorylation
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Main Purpose:
-oxidation of fuels
-provides carbon precursors for biosynthesis
Most important control site:
-Tight coupling- electron donors are recycled only when ADP is simultaneously phosphorylated.
Abundance of NADH and ATP slow citrate synthase, Isocitrate DH and AKG DH.
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Pentose Phosphate Pathway
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-Main Purpose:
--Synthesis of NADPH and ribose 5-phosphate.
--Stage 1-oxidative and irreversible
--Stage 2- non-oxidative and reversible
-Most important control site:
Glucose-6-phosphate DH.
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Gluconeogenesis
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Main purpose: synthesis of glucose from non-carbohydrate precursors.
Most important control site:
-Fructose bisphosphatase
PEPCK
--Generally reciprocally regulated with glycolysis.
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Glycogen Synthesis and degradation
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Most important control site:
synthesis and degradation are reciprocally controlled by hormonal phosphorylation and dephosphorylation cascades
Synthesis-Glygogen synthase
Degradation-Glycogen phosphorylation.
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Fatty Acid Synthesis and Degradation
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-Most important control site:
-synthesis-Acyl Coa Carboxylase.
Degradation: rate is coupled to the synthesis of ATP (like TCA cycle)
-Malonoyl co A inhibits carnitine acyl transferase.
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Cytosol:
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Glycolysis
Glycogen Synthesis
Glycogen degradation
Fatty acid synthesis
Pentose Phosphate pathway
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Mitochondria
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Fatty Acid Degradation
Citric acid cycle
Oxidative phosphorylation
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Both
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gluconeogenesis
amino acid degradation
--Circulatory system is required to transport metabolic fuels, intermediates and waste products between tissues.
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Insulin
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Liver: increase in glycogen synthesis.
increase in lipid synthesis
decrease in gluconeogenesis
Muscle: Increase in glucose uptake
increase in glycogen synthesis
Adipocytes: increase in glucose uptake
increase in lipid synthesis
decrease in lipid degradation.
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Glucagon
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Liver: increase in glycogen degradation
increase in beta oxidation
increase in gluconeogenesis
Muscle:NO effect
Adipocytes:decrease in lipid synthesis
increase in lipid degradation
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Epinephrine
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Liver:increase in glycogen degradation
increase in beta oxidation
increase in gluconeogenesis
Muscle: increase in glycogen degradation
Adipocytes: decrease in lipid synthesis
increase in lipid degradation.
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The need for ATP
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most energy metabolic pathways are regulated by the need for ATP.
Cells sense the ATP level via the [AMP]
Many key reg enzymes are activated or inhibited by AMP
AMP dependent protein kinase phosphorylates many enzymes including pfk2/fbp2 hormone sensitive lipase acetyl coa carboxylase,…
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Effects of AMPK
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Targets heart PFK-2 activating it increasing glycolysis (opposite of the effect of PKA in liver)
inhibits ACC decreasing concentration of malonoyl coa increasing transport of FA into mitochondria.
inhibits ACC, HMG-CoA reductase, Glycogen synthase in Liver.
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TPP
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Carries activated acetaldehyde groups.
Thiamine (Vitamin B1) is an essential vitamin and deficiencies cause beri beri.
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CoA
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CoA functions as a carrier of acetyl and other acyl groups.
Acetyl coA is a high energy compound.
The DeltaGnot' for the hydrolysis of its thioester bond is -31.5 kj/mol.
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Lipoic Acid
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three forms: oxidized,reduced, and acetylated.
Long arm of lipoyllysyl allows movement between active sites.
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PLP
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The enzymes catalyzing transamination require the coenzyme pyridoxal-5'-phosphate or PLP.
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Unique cofactors of AA metabolism
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Tetrahydrobiopterin-electron carrier
methyl carriers- SAM and THF
Many biological processes involve the addition of a C1 unit.
Carboxylation reactions use biotin.
Methylation reactions use either SAM or THF.
THF is the most versatile because it can transfer C1 units in several oxidat…
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Synthesis of Thymine nucleotides
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CTP->CDP->dCDP->dCTP->dUTP->dUMP->dTMP.
dUTP->dUMP (dUTPase- very important reaction for the integrity of DNA).
CDP-> dCDP -ribonucleotide reductase.
dUMP-->dTMP- Thymidylate synthetase.
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Which of the following involves malic enzyme?
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involved in odd chain fatty acid B-oxidation.
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The Ch3 carbon in palmitic acid (c16) comes directly from
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acetyl coa.
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lipid metabolism
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conversion of 3-ketoacyl-ACP to 3-hydroxyacyl-ACP requires NADPH.
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Ketone bodies
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the synthesis of acetoacetate requires HMG-CoA synthase
acetoacetyl CoA-> HMG CoA
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After about 5 days of fasting, what metabolic pathways act as the primary supplier of fuel?
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Ketone body synthesis.
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Before a fatty acid can be oxidized, it must first be
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activated by acyl CoA synthetase
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Every round of beta oxidation produces:
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1 Fadh2, 1 NADH, and 1 Acetyl CoA.
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A double bond at an even number carbon in a fatty acid reduces the energy yield from the oxidation of that fatty acid by
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2.5 ATP.
odd reduces by 1.5 ATP
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The purpose of ketone body formation is
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to provide the brain with fuel in prolonged fasts.
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Fatty acid synthesis requires:
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Acetyl CoA carboxylase, Malonoyl coA, NADPH, and Fatty Acid Synthase.
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The ability to elongate a fatty acid resides in:
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The mitochondria-acetyl coa, 1 nadh and 1 nadph.
The ER- malonoyl coa and 2 nadph.
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Allosteric activation and inhibition of acetyl coa carboxylase occur respectively by:
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Citrate and long chain fatty acyl coA's
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The rate limiting and committed step of cholesterol synthesis is:
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HMG CoA reductase
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Intracellular protein degradation occurs through what 2 processes:
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Lysosomal degradation and Ubiquitination.
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Secondary messengers are:
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Ca+2/ cAMP, diacylglycerol,and inositol triphosphate.
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What is the primary reason why the liver is capable of maintaining blood glucose concentrations.
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the pretense of glucose 6 phosphatase
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skeletal muscle has all of the following characteristics:
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the ability to consume up to 90 percent of the oxygen we breath
Participates in the core cycle and the glucose alanine cycle
has a small glycogen store
uses ATP and creatine to synthesize phosphocreatine at times of rest.
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High levels of blood sugar activate.
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liver pyruvate DH.
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Which of the following oxidizes complex 3 of the electron transport chain in mitochondria?
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Cytocrome C- it absorbs the electron from cyt c1, thus oxidizing cyt c1 which is part of complex 3.
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Complex 2 transfers a total of __ H+ across the inner mitochondrial membranes per pair of electrons transported.
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0 h+.
Complex 1: 4
Complex 3: 4
Complex 4: 2
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Metabolic pathways often converge on intermediates. the major converging points include:
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Pyruvate and acetyl coa.
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Which of the following is NOT an essential amino acid?
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Glycine.
Essential amino acids: PVT TIM HALL
phe, val, trp, the, ile, met, his, arg, leu, lys.
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Heme degradation coupling:
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bilverdin: green
sterocobilin- pigment of feces.
urobilinogen- precursor of stercobilin and urobilin.
urobilin: yellow color of urine.
billirubin: lipophilic.
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The purine precursor is:
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IMP
UMP is the pyrimidine precursor.
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IMP is synthesized as:
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a nucleotide, which means it has a ribose and a phosphate attached to the nitrogenous base.
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What is the purpose of purine salvage?
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To recycle purines for reincorporation in nucleic acids.
Cytosine CANNOT be salvaged.
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What is the substrate for ribonucleotide reductase?
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NDP.
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Processes
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Catabolism: convergent.
anabolism: divergent.
catabolism: produces atp, nadh, nadph
anabolism. produces macromolecules through using tap and nadph.
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Pentose phosphate pathway
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produces NADPH and R-5 P for use in anabolic pathways.
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Reaction coupling is:
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Responsible for the spontaneity of anabolic pathways.
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Excess cholesterol is:
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converted into bile salts and concentrated into the gallbladder and eliminated in the feces.
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What is the corresponding intermediate for asparagine synthetase?
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Adenylated intermediate.
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Bilirubin is formed by the degradation of
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heme
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Cysteine can be synthesized by the human body if given a source of the following essential amino acid?
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Methionine.
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What is the corresponding intermediate for Phosphoserine Aminotransferase?
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pyridoxamine monophosphate intermediate.
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Enzymes involved in activated met cycle.
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SAM methylase
S-adenosylhomocysteinase
methoinine adenosyltransferase
methionine synthase.
Cystathionine synthase/lyase is not involved, its involved in cysteine synthase.
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The ribose component of nucleotides is generated by:
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Pentose phosphate pathway.
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Ribonucleotidereductase
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activated by ATP
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How many glutamine molecules are used in the de novo biosynthesis of AMP?
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2
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What is the corresponding intermediate for CPS II?
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carboxy phosphate
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What is the corresponding intermediate for GMP synthetase?
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adenylated intermediate.
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The conversion of IMP into GMP requires which of the following amino acids?
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Glutamine.
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Acetyl coa carboxylase:
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Palmitoyl coa shifts the protein to inactive state
citrate shifts the protein to the active state
phosphorylates modulates the binding affinity of citrate and palmitoyl coa.
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Regulation of fatty acid synthesis in humans is affected by all of the following:
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acyl coa carboxylase catalyzes the first committed step in fatty acid biosynthesis.
citrate stimulates acetyl coa carboxylase
malonoyl coa binding to carnitine acyltransferase lowers the concentration of fatty acyl coa available for beta oxidation.
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The main sources of NADPH for fatty acid biosynthesis are:
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malic enzyme and Pentose phosphate pathway.
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Nitric ocide is produced from what reaction?
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arginine to citruline.
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Glycolysis
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in liver ccells stimulated by epinephrine phosphoglycerate kinase converts atp--> ADP + pi.
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glucose metabolism
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pyruvate decarboxylase produces acetaldehyde and carbon dioxide in an irreversible reaction. (Uses TPP)
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anaerobic metabolism
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under anaerobic conditions, lactate DH converts NADH into NAD+
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glycogen:
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to ensure proper coordination of their activity, glycogen synthase and glycogen phosphorylase are both regulated by phosphorylase kinase mediated phosphorylation.- when one pathway is on, the other one is off.
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the next step in oxidation of Ch3-Ch=Ch-ch-co-S-coa in mitochondria would involve?
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enoyl coa isomerase.
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carnitine acyl transferase I:
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is inhibited by malonoyl CoA.
this is the enzyme that transports an activated fatty acid that has carnitine attached to it form the cytosol into the mitochondria.
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Odd chain fatty acid degradation
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propionoyl coa-> methylmalonoyl coa-> succinyl coa-> furmarate
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Reactions requiring vitamin B12 (cobalamine)
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methyl malonoyl coa mutase, and methionine synthase (radical intermediate)
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__ is required to transport acetyl coa from mitochondria into the cytoplasm.
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citrate cynthase is used to convert acetyl coa into citrate which will then transport from the mitochondria into the cytosol.
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acetyl coa carboxylase produces:
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malonoyl coa.
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the brain contains GLUT 3 transporters because:
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it maximizes glucose uptake.
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Glucose 6 phosphate has several fates including:
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production of NADPH and ribose5phosphate via PPP.
conversion to acetyl coa via glycolysis and pyruvate dh
a product of glycogen degradation or a precursor of glycogen synthesis
a product of gluconeogenesis.
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catabolic hormones include:
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epinephrine and glucagon.
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In the well fed state:
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we have high glucose, which turns on glycolysis, glycogen synthesis, and FA bio synthesis.
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the difference between the fasting and the starving state is:
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protein catabolism is limited in the starving state (longer than 4-5 days)
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Glycogen-
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acts as a fuel source of the body in the post absorptive state as well as for muscle at times of activity.
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the liver is capable of all of the following functions:
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gluconeogenesis, fatty acid synthesis, pentose phosphate pathway, purine synthesis.
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Net loss of nitrogen:
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arginase
glutamate DH
asparaginase.
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the direct precursor of urea:
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arginine.
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Tetrahydrofolate functions as a:
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carbon carriier.
carboxyl carrier is biotin
methyl carrier is SAM
electron sink- NAD+
schiff base- lys and plp--aldolase reactions.
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SAM is produced by and used as:
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methionine degradation, a methyl donor.
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ketogenic amino acids include:
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leucine and lysine.
PITTT are both- phe ile trp try and thr
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alpha ketoglutarate is the direct precursor of:
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gultamate and succinyl coa.
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Fat is transported from intestine to blood by the:
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lymphatic system.
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PLP
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aminotransferases use this, glycogen phosphorylase.
serine hydroxymethyltransferase, serine dehydratase
cystathionine reactions
more
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Biotin
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carboxylase reactions.
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TPP
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decarboxylase reactions, pyruvate DH, transketolase reactions.
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Cobalamine:
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methyl malonoyl coa mutase, methionine synthase
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THF
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thymidylate synthase, more.
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What is the principle cause of muscle fatigue?
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Muscle acidosis- buildup of H+
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a common side effect of alcoholics is a condition called fatty liver. what is the cause of this condition?
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triacylglycerol levels in the liver are elevated.
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What glucose transporter is insulin sensitive and how is this expressed?
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GLUT 4 is insulin sensitive.
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The cori cycle
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is the production of lactate in the muscle and the production of glucose in the liver from that lactate. - gluconeogenesis in the liver is part of the core cycle, and glycolysis in the muscle.
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Why is there an elevated respiration rate even after intense muscular activity is complete?
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because o2 is required so the liver and muscle can resynghesize their energy stores.
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hormonal regulation
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high levels of glucagon lead to inhibition of pyruvate kinase in the liver, to allow glucose breakdown in the muscle.
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Gluconeogenesis - Flashcards