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102 Cards in this Set
- Front
- Back
What is the difference between proteoglycans and glycoproteins?
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Proteoglycans - Glycosaminoglycan chains (contains repeating disaccharides)
Glycoproteins - Oligosaccharide chains (no repeating disaccharides) |
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All glycosaminoglycans except hyaluronic acid are synthesized where?
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Golgi
Hyaluronic acid synthesized in plasma membrane |
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Main locations of hyaluronic acid
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cartilage, synovial fluid, vitreous humor of the eye
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Medical uses of hyaluronic acid
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Used in eye surgery and treatment of osteoarthritic pain
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Most abundant glycosaminoglycan in the human body
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Chondroitin sulfates
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Increased accumulation of __________ in mitral valves is associated with thickening and abnormal displacement of the valve into the left atrium of the heart (mitral valve prolapse).
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dermatan sulfate
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The only glycosaminoglycan that does not contain an acidic sugar
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Keratan sulfates
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Glycosaminoglycan used as a anticoagulant in medicine
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Heparin
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The linkage region to which a GAG is attached to a protein to form a proteoglycan.
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Hydroxyl of serine or amide of asparagine
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Name for cartilage proteoglycan
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Aggrecan
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A group of lysosomal storage diseases.
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Mucopolysaccharidoses
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Functions of glycoproteins
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Cell surface recognition (including binding sites for pathogens)
Blood group antigens Extracellular matrix molecules Mucins Plasma proteins |
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Where is the oligosaccharide chain built during the synthesis of an O-linked glycoprotein?
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Golgi
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The only glucose transport protein that is insulin independent
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GLUT-2
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Glucose transport protein in muscle and adipose cells
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GLUT-4
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Glucose transport protein in hepatic cells
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GLUT-2
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Glucose transport protein in the brain
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GLUT-1 and GLUT-3
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Phosphorylation of glucose into G-6-P is catalyzed by:
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Hexokinase
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Enzyme the phosphorylates glucose in the liver. Has a high Km.
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Glucokinase
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The isomerisation of G-6-P into F-6-P is catalyzed by what enzyme?
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Phosphoglucose isomerase
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The phosphorylation of F-6-P to F-1,6-BP is catalyzed by what enzyme?
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phosphofructokinase-1 (PFK-1)
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Irreversible reaction in glycolysis. The "committed" step.
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Phosphorylation of F6P
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Enzyme that catalyzes the cleavage of F-1,6-BP
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Aldolase
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This compound inhibits enolase and results in a decrease in ATP synthesis
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Fluoride
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Inhibits glyceraldehyde 3-P dehydrogenase
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Arsenate
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Possible fates of pyruvate
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Alanine (carrier of amino groups from muscle to liver)
Oxaloacetate (ATP used) Lactate (NADH used) Acetyl-CoA/CO2 (In presence of O2) |
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Isoenzymes of Lactate dehydrogenase are used in detecting the following diseases: (4)
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Cardiac (myocardial and pulmonary infarctions)
Hepatic (hepatitis and cirrhosis) Skeletal muscle (hypoxia and muscle trauma) Neoplastic disorders: leukemias and large tumors |
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Pyruvate dehydrogenase requires what 5 coenzymes in order to function?
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Thiamine pyrophosphate
Lipoic acid CoA FAD NAD+ |
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Enzyme responsible for the isomeration of dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3-phosphate (GAP).
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Triose phosphate isomerase
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Two possible way to ways to rexoidize NADH -> NAD+
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ETC in the presence of oxygen
Pyruvate + NADH <-> Lactate + NAD+ |
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Possible outcomes of pyruvate metabolism
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Alanine (carrier of amino groups from muscle to liver)
Oxaloacetate (used to replenish TCA cycle or in gluconeogenesis) Lactate Acetyl-CoA (Used in TCA cycle or for fatty acid synthesis) |
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End products of glycolysis
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2 ATP
2 NADH 2 Pyruvate |
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Low blood pH (high lactate) inhibits which glycolytic enzyme?
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Phosphofructokinase
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High levels of ATP inhibit which 2 glycolytic enzymes?
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Phosphofructokinase
Pyruvate kinase |
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Sources of Acetyl-CoA
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Plamitate (Fatty acid)
Acetoacetate (ketone body) Pyruvate Ethanol |
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The conversion of GTP and ATP is catalyzed by what enzyme?
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nucleoside diphosphate
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In the brain, this TCA intermediate is converted into the neurotransmitter GABA
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a-ketoglutarate
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During fasting, this TCA intermediate is transported into cytosol and used in gluconeogenesis.
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Malate
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This TCA intermediate is used in fatty acid synthesis
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Citrate
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This TCA intermediate is used to form heme
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succinyl CoA
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These 2 TCA intermediates can be used for amino acid synthesis
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Oxaloacetate and a-ketogluterate
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Pyruvate carboxylase is activated by _________.
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Acetyl CoA
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This enzyme forms oxaloacetate from pyruvate
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Pyruvate carboxylase
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The oxidation of one NADH yields roughly how many ATP?
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~2.5
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The oxidation of one FADH2 yields roughly how many ATP?
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~1.5
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Mitochondrial transport protein that transports ADP from cytosol and ATP to cytosol
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Adenine nucleotide translocase (ANT)
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Mitochondrial transport protein that transport Pi into mitochondria
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Phosphate transporter
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This mitochondrial transport shuttle is only active when NADH/NAD ratio is higher in cytosol than in the mitochondria.
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malatate-asparate shuttle
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In the glycerophosphate shuttle, roughly how many ATP are generated for each NADH oxidized?
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~1.5
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In the malate-aspartate shuttle, roughly how many ATP are generated for each NADH oxidized?
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~2.5
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Poision that binds to ATP synthase and blocks H+ channel. Can result in high levels of lactate in blood and urine.
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Oligomycin
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Two poisons that inhibit complex IV in ETC
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Carbon monoxide and cyanide
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Poison used as an insect control in gardens and on pets. Inhibits complex I
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Rotenone
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Poison that inhibits complex I and is used as a sedative and a hypnotic.
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Amytal
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A fungicide that inhibits complex III
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Antimycin A
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Tissues/cells that do not use fatty acids during fasting as an energy source
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Red blood cells (no mitochondria)
Adipocytes Brain |
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The process of adipose tissue being degraded into triglycerides during a fasting state is stimulated by:
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elevated glucagon/insulin ration and high epinephrine levels
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Fatty acids released from the adipose tissue are bound to _________ and delivered to target tissues
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albumin
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Degradation of fatty acids mainly occurs where?
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mitochondria
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In order to be metabolized, fatty acids have to be converted to _________.
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Fatty acyl CoA
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Fatty acyl CoA can be converted to: (3)
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Energy (most tissues, liver)
Storage - Triacylglycerols (adipocytes) Membrane lipids |
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Rate limiting enzyme for transporting long chain fatty acids into the mitochondria
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Carnitine palmitoyl transferase I (CPTI)
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Storage site for most carnitine in the human body
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Skeletal muscle
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During B oxidation of long chain fatty acids, what is generated during every cycle?
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FAD(2H), NADH, Acetyl CoA
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Number of ATP generated from one Acetyl CoA in the TCA cycle
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10
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Where does w oxidation take place?
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ER
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The main difference between peroxisomal degradiation of fatty acids and beta oxidation is:
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No FAD(2H) production in peroxisomal degradition
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The 3 ketone bodies
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Acetoacetate
B-Hydroxybutyrate Acetone (not used physiologically) |
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Liver enzyme responsible for converting glucose 6-phosphate to glucose. This enzyme is not present in muscle cells.
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Glucose 6-phosphatase
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Chain elongation of glycogen is catalyzed by what enzyme?
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glycogen synthase
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Glycogen branching enzyme
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4:6 transferase
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Regulated enzyme in glycogenolysis
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glycogen phosphorylase
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What part of the cell is glucose 6-p converted to glucose?
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ER
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In the liver, after glucose 6-p is converted to glucose, the glucose is transported into the cytosol via which transporter?
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GLUT-7
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Glucose is transported out of liver cells into circulation via which transporter?
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GLUT-2
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Positive allosteric regulator of glycogen synthesis.
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Glucose 6-Phosphate
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Allosteric regulators of glycogen degradation
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Low glucose (liver only)
High AMP (Muscle only, generated during exercise) Low glucose 6-phosphate Low ATP |
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Glycogen degradation is activated by phosphorylation of ________
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Glycogen phosphorylase
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Glycogen synthesis is inhibited by phosphorylation of ________
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Glycogen synthase
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Epinephrine acts through what 2 receptors?
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B2-adrenergic
A1-adrenergic |
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The main activator of glycogenolysis and glycolysis in exercising muscle
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AMP
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The most sensitive reflection of energy need in skeletal muscle during exercise.
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Changes in AMP levels
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The major regulated step of beta oxidation in muscle
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Carnitine-palmitoyl transferase-1 (CPT-1)
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Allosteric inhibitor of Carnitine-palmitoyl transferase-1 (CPT-1)
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Malonyl CoA
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In fasting conditions, high levels of ______ and _____ in cardiac muscle will inhibit glycolysis.
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acetyl CoA
Citrate (PFK-1 and PDH are inhibited) |
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2 Enzymes lacking in muscle that prevent gluconeogenesis
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glucose 6-phosphatase
pyruvate carboxylase |
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Symptoms for lactate dehydrogenase deficiency
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Muscle cramping and myoglobinuria after intense exercise
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Sources of lactate
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RBCs
Lens and cornea Skin Skeletal muscle |
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How much ATP is required to form a glucose molecule from lactate?
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6
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Enzyme that catalyzes Alanine -> Pyruvate
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Alanine aminotransferase
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Deaminated amino acids used in gluconeogenesis
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Alanine -> Pyruvate
Aspartate -> Oxaloacetate Glutamate -> a-ketogluterate |
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Pathway of glycerol in gluconeogenesis
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Glycerol -> Glycerol 6-phosphate -> Dihydroxyacetone phosphate
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Symptoms of biotinidase deficiency
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seizures
hypotonia breathing problems delayed development If not treated: hearing loss vision loss alopecia (hair loss) ataxia skin rashes candidiasis |
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Allosteric inhibitor of fructose-1,6-bisphosphatase
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Fructose-2,6-bisphosphate
(Product of PFK-2: F6P -> F2,6BP) |
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Decrease in fructose-2,6-bisphosphate causes:
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Inhibition in glycolysis
Activation of gluconeogenesis Activation of lipolysis |
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Increase in fructose-2,6-bisphosphate causes:
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Glycogenesis
Glycolysis Lipogenesis |
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Increased acetyl-CoA in the liver causes:
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Increased gluconeogenesis
Inhibition of pyruvate dehydrogenase Allosteric activation of pyruvate carboxylase |
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Vitamin B1 (thiamine) levels are assessed byt the activity of ________________.
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Red blood cell transketolase.
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Major uses of NADPH
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Fatty acid synthesis
Cholesterol synthesis Steroid synthesis Nitric oxide synthesis Deoxyribonucleotide synthesis |
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Defensive utilization of NADPH
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Protection against oxidative damage (erythrocytes)
Detoxification of xenobiotics Superoxide synthesis |
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Enzyme that generates superoxide in the phagolysosome to destroy bacteria.
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NADPH Oxidase
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To synthesize glucose (gluconeogenesis), the liver can use what?
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Amino Acids
Glycerol Lactate |