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72 Cards in this Set
- Front
- Back
Gluconeogenesis
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de novo synthesis of glucose from non carbohydrate precursors
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Where does gluconeogenesis occur?
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Liver and kidney
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What cannot be converted to glucose?
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acetyl Co A
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Overall reaction gluconeogenesis
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2 pyruvate + 4 ATP + 2 GTP +2NADH + 6 H20-->glucose + 4ADP+ 2 GDP + 6Pi + 2NAD+
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What enzyme is used instead of hexokinase in gluconeogenesis?
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G-6-pase
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What enzyme is used in gluconeogenesis instead of PFK?
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fructose 1,6 bisphosphotase
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What enzyme is used in gluconeogenesis instead of pyruvate kinase?
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Pyruvate carboxylase + PEP carboxykinase
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Pyruvate Carboxylase
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pyruvate + CO2 + H2O+ATP -->OAA+ADP+Pi+2H+
needs biotin |
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Is ATP required for carboxylation?
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yes, some of the energy released by ATP hydrolysis is conserved in the new bond formed between the carboxyl group and pyruvate.
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PEP carboxykinase
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oxaloacetate + GTP --> phosphoenolpyruvate + GDP + CO2
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What is the energy requirement for converting oxaloacetate to phosphoenolpyruvate?
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Two high energy bonds (one from ATP in PEP carboxylase rxn and one from GTP in PEP carboxykinase) are required to get through last irreversible step in glycolysis
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Fructose 1,6 bisphosphotase
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Fructose 1,6 bisphosphate + H2O-->Fructose 6 P + Pi
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Glucose 6 Phosphotase
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Glucose 6 P + H2O-->Glucose + Pi
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What enzymes catalyze irreversible reactions?
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hexokinase, PFK ,and pyruvate kinase
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Kinase
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enzyme that transfers a phosphate group from ATP
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Isomerase
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enzyme that converts one isomer into another
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Aldolase
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enzyme that catalyzes aldol condensation
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Dehydrogenase
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removes hydrogens by oxidation, usually require NAD+
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Mutase
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enzyme that changes one group into anothe group, moves phosphates
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Enolase
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converts C=C to alcohol
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Input to glycolysis
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glucose, 2 ATP, 4 ADP, 2 NAD+
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Aerobic output glycolysis
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2 NADH, pyruvate, 2 ADP, 4 ATP
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Net energy gain of glycolysis
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2 ATP, 2 NADH
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First step of glycolysis
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Hexokinase, converts glucose to G-6-P, traps glucose in the cell
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Is first step of glycolysis reversible?
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no, favorable, G<0
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Third step of glycolysis
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PFK
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Name enzyme that catalyzes glycogen synthesis
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glycogen synthase
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Name enzyme that catalyzes glycogen degradation
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glycogen phosphorylase
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Phosphorolysis
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cleavage of an ester by a phosphate group
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Does phosphorylation lead to glycogen synthesis or degradation?
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Phosphorylation activates glycogen phosphorylase leading to glycogen degradation, dephosphorylation activates glycogen synthase leading to synthesis
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Energetic efficiency of glycolysis
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50%
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Where is pyruvate carboxylase located?
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mitochondria
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What is the role of Mg in 1st step of glycolysis
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shields negative charge
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2nd step of glycolysis
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phosphoglucose isomerase, G-6-P is transfered to F-6-P
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What kind of reaction is 2nd step of glycolysis
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isomerization
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What changes occur in 2nd step of glycolysis
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rearrangement of C-O bond from 6 membered ring to 5 membered ring
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PFK
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3d step of glycolysis, fructose-6-P is converted into 1,6 fructobisphosphate
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Step 4 of glycolysis
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aldolase catalyzes cleavage of FBP into two 3 C molecules
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what are the names of two 3 C molecules formed as a result of Step 4
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3 GAP and DHAP
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Pyranose
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6 membered ring
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furanose
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5 membered ring
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Anomeric carbon
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chiral center gained upon cyclization
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alpha anomer
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OH group on C1 down
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beta anomer
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OH group on C1 up
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example of pyranose
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glucose, fructose
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example of furanose
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ribose
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AMino sugars, example
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modified monosacharides
glucosamine, sialic acid |
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Sucrose structure
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Anomeric carbon of glucose forms a bridge with anomeric carbon of fructose
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Lactose structure
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glycosidic bond between galactose and glucose
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Glycosidic bond
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condensation of anomeric carbon with hydroxyl groups on another monosaccharide
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which is the anomeric carbon in aldose
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C1
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which is anomeric carbon in ketose
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C2
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Name structural polysaccharides
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chitin and cellulose
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Cellulose
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structural polysacharide of plants, polymer of beta 1->4 glucose, forms flat sheets with multiple H bonds between strands
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cellulose properties
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strong, stress resistant, water insoluble despite of hydrophilic residues
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CHitin
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contains N acetylglucosamine, part of insect exosceleton, not branched tightly packed
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Name storage polysaccharides
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Starch and glycogen
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Starch
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amylose and amylopectin
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Amylose
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linear glucose homopolymer, glucose 1->4, similar in structure to alpha helix in proteins
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Amylopectin
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branched, has alpha 1->6 branches
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GLycogen
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in animals only, more highly branched then starch
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Glycoprotein
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form of protein modification, play important role in directing location of the protein, define blood group antigen
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Amino acid sequence in N linked glycans
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Asn-x-Ser/Thr
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Structure of chloroplast
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3 membranes, thylakoid membrane folded to make lamellae, that are stacked to make grana, stroma - protein rich solution
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what allows chlorophyl to absorb electrons
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conjugated rings with Mg in the center
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Name accessory pigments
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carotenoids, phycocyanin
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Photosystem I
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uses energy of light to reduce NADP to NADPH
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Photosystem II
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uses light energy to oxidize H2O, reduce Q and make ATP
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Cytochrome b6f complex
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electron transfer from PS II to PS I
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Reaction center in PS I
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P700
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Reaction center in PS II
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P680
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How is ATP generated in photosynthesis?
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By establishment of proton gradient as electrons flow from PS II to PS I
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