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Ch 21, biochem, carb. metabolism


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glucose is converted to Glu-6-phosphate by?
Glu-6-phosphate can enter other metabolic cycles such as?
1) glycolysis
2) pentose phosphate pathway
3) glycogen synthesis
pentose phosphate pathway
1) glucose
2) Glu-6-phosphate
3) Fruc-6-phos
4) glyceraldehyde-3-phos
5) pyruvate
ribulose-5-phosphate can be produced from?
1) gluc-6-phos or
2) fruc-6-phos
ribulose-5-phos can be used for?
nucleotide biosynthesis
in the conversion of glu-6-phos to ribulose-5-phos, 2 molecules of NADP+ are converted to?
pyruvate produced from pentose phosphate pathway can enter?
What is pentose phosphate pathway?
an alternative pathway for glucose degradation that provides the cell with reducing power in the form of NADPH
NADPH stands for?
nicotinamide adenine dinucleotide phosphate
conversion of
1) glucose <
2) glu-6-phos <
3) pyruvate
pyruvate produced by glycolysis enters what cycle for production of energy?
TCA cycle (tricarboxylic acid)
which glucose metabolism is almost exact reverse of glycolysis?
in gluconeogenesis, glucose is produced from?
1) lactate
2) pyruvate
3) amino acids
(from noncarb. precursors)
glycogen synthesis
1) glucose
2) glu-6-phos
3) glucose-1- phos
4) glycogen
the metabolic pathway that results in the addition of glucose to growing glycogen polymers when BS levels are high
the biochemical pathway that results in the removal of glucose molecules from glycogen polymers when blood glucose levels are low
step of glycogenolysis
1) glycogen
2) glu-1-phos
3) glu-6-phos
4) glucose
ATP (adenosine triphosphate) serves as?
a "go-between" molecule that couples exergonic catabolism reactions to endergonic anabolic reactions
ATP "captures" energy as?
phosphosanhydride bonds
what reaction of the anhydride bonds provides energy for anabolism?
what enzyme in saliva cleaves larger complex sugars (like starch) into smaller units?
alpha-amylase is destroyed by?
stomach acid
duodenum neutralizes stomach acid with ----(1), and also secretes ----(2).
1) bicarb
2) alpha-amylase
small polysaccharide units (ex. maltose) left and are converted into monosaccharides by?
glycosidases are found on?
cell walls of intestinal villi
splitting into monosaccharides allows absorption across membrane via?
facilitated transport
carbohydrate transport into tissues
1) GLUT (glucose transporters)
2) pinocytosis
3) pores between cells or in basement membrane
catabolism: stage 1
hydrolysis of macromolecules to small subunits (food molecules are degraded)
stage 1: polysaccharides
1) begins in the mouth with amylase action on starch
2) continues in SI to form monosaccharides
stage 1: proteins
1) begins in the stomach
2) by SI, converted to amino acids
stage 1: fats
1) begins in SI
2) to fatty acids and glycerol
stage 2 of catabolism
conversion of monomers to a form that can be completely oxidized
stage 2: sugars
1) glycolysis and
2) TCA cycle
stage 2: fatty acids
enter TCA cycle as acetyl CoA
stage 3 of catabolism
1) complete oxidation/ATP produced
2) acetyl CoA enters the TCA cycle and electorons and H atoms are harvested as CO2 is produced
glycolysis step 1:
glucose + ATP is converted to?
glucose-6-phosphate + ADP by hexokinase
glycolysis step 2:
glucose-6-phosphate + ADP is converted to?
fructose-6-phosphate by phosphoglucose isomerase
glycolysis step 3:
fructose-6-phosphate + ATP is converted to?
fructose-1,6-bisphosphate + ADP by phosphofructokinase
glycolysis step 4:
fructose-1,6-bisphosphate is converted to?
2)dihydroxyacetone phosphate by aldolase
glycolysis step 5:
dihydroxyacetone phosphate is converted to?
D-glyceraldehyde-3-phosphate by triosephosphate isomerase
glycolysis step 6:
D-glyceraldehyde-3-phosphate + NAD+ + HPO4 2- is converted to?
glycerate-1,3-bisphosphate + NADH + H+ by glyceraldehyde 3-phosphate dehydrogenase
glycolysis step 7: glycerate-1,3-bisphosphate + ADP is converted to?
3-phosphoglycerate + ATP by phosphoglycerate kinase
glycolysis step 8:
3-phosphoglycerate is converted to?
2-phosphoglycerate by phosphoglycerate mutase
glycolysis step 9:
2-phosphoglycerate is converted to?
PEP (phosphoenolpyruvate) + H2O + ADP by enolase
glycolysis step 10:
PEP is converted to?
pyruvate + ATP by pyruvate kinase
hexokinase (step 1) is inhibited by?
glucose-6-phosphate, ATP
PFK (phosphofructokinase, step 3) is activated by?
fructose-2,6-bisphosphate, AMP
PFK (phosphofructokinase, step 3) is inhibited by?
citrate, ATP
pyruvate kinase (step 10) is activated by?
fructose-1,6-bisphosphate, AMP
pyruvate kinase (step 10) is inhibited by?
Acetyl-CoA, ATP
pyruvate + NADH + H+ is converted to?
lactate + NAD+ by lactate dehydrogenase
fermentation 2:
pyruvate is converted to?
acid aldehyde by pyruvate decarboxylase
acid aldehyde + NADH + H+ is converted to?
ethanol + NAD+ by aldehyde dehydrogenase
pentose phosphate (PP) pathway: stage 1
1) oxidative stage
2) NADPH for biosynthesis is produced
PP pathway: stage 2
three ribulose-5-phosphate result
PP pathway: stage 3
1) ribose-5-phosphate
2) two xylulose-5-phosphate
3) two fructose-6-P
4) glyceraldehyde-3-P
gluconeogenesis makes glucose from?
1) lactate
2) glycerol
3) most AA
starting materials primarily in the liver
3 nonreversible steps of glycolysis must be bypassed with new routes
1) pyruvate --> PEP
2) fructose-1,6-bisP --> fructose-6-P
3) glucose-6-P --> glucose
pyruvate + ATP + CO2 + H2O is converted to?
oxaloacetate + ADP + Pi + H+ by pyruvate carboxylase
oxaloacetate + GTP is converted to?
PEP (phosphoenol pyruvate) + GDP + CO2 by phosphoenolpyruvate carboxykinase
fructose-1,6-bisP is converted to?
fructose-6-P by fructose-1,6-bisphosphatase
glucose-6-P is converted to?
glucose by glucose-6-phosphatase
Cori cycle
lactate from skeletal muscle is transferred to the liver where it is converted to pyruvate then glucose which can be returned to the muscle
glycogenolysis (glycogen degradation) is controlled by?
1) glucagon (pancreas)
2) epinephrine (adrenal gland)
glcogenolysis step 1
glycogen phosphorylase catalyzes removal of an end glucose as glucose-1-P
glycogenolysis step 2
debranching enzyme catalyzes removal of the last glucose at an alpha(1->6) branch as glucose
glycogenolysis step 3:
glucose-1-P is converted to?
glucose-6-P by phosphoglucomutase
1) elevates glucokinase
2) activates glycogen synthetase
insulin inhibits
glycogen phosphorylase
glucagon stimulates
glycogen phosphorylase
glucagon inhibits
glycogen synthetase
are a core protein with many long chains of glycosaminoglycans attached
proteoglycans are found in?
1) synovial fluids
2) vitreous humor
3) cartilage
4) bone
are short chain, usually branched carbs attached to proteins
glycoproteins are found in?
1) mucus
2) blood
3) membrane
are lipid core (sphingolipid) with attached monosaccharides
glycolipids are found in?
1) cell membranes
2) may be part of cell recognition sites

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