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