Ch 21, biochem, carb. metabolism
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- glucose is converted to Glu-6-phosphate by?
- hexokinase
- 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?
- NADPH
- pyruvate produced from pentose phosphate pathway can enter?
- glycolysis
- 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
- glycolysis
-
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?
- gluconeogenesis
- 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 - glycogenesis
- the metabolic pathway that results in the addition of glucose to growing glycogen polymers when BS levels are high
- glycogenolysis
- 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?
- hydrolysis
- what enzyme in saliva cleaves larger complex sugars (like starch) into smaller units?
- alpha-amylase
- 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
- 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? -
1)D-glyceraldehyde-3-phosphate
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
-
fermentation:
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?
-
noncarbohydrate
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
- insulin
-
1) elevates glucokinase
2) activates glycogen synthetase - insulin inhibits
- glycogen phosphorylase
- glucagon stimulates
- glycogen phosphorylase
- glucagon inhibits
- glycogen synthetase
- proteoglycans
- 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 - glycoproteins
- are short chain, usually branched carbs attached to proteins
- glycoproteins are found in?
-
1) mucus
2) blood
3) membrane - glycolipids
- are lipid core (sphingolipid) with attached monosaccharides
- glycolipids are found in?
-
1) cell membranes
2) may be part of cell recognition sites