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| anomer |
-differ in configuration at C1 (alpha or beta) |
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mcs5109 Thu, 28 Jan 2010 07:20:36 GMT |
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| epimers |
-differ by only the configuration of a single -OH other than at C1 |
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mcs5109 Thu, 28 Jan 2010 07:20:36 GMT |
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| How dietary starch/glycogen and intracellular glycogen is broken down |
-dietary starch/glycogen is first broken down in mouth and then in intestines by hydrolysis of alpha (1-->4) linkages
starch/glycogen ---> oligosaccacharides ---> glucose
-intracellular glycogen is broken down by glycogen phosphorylase into glucose-1-phosphate
-phosphoglucomutase converts G-1-P to G-6-P enters glycolysis |
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mcs5109 Thu, 28 Jan 2010 06:53:00 GMT |
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| Fate of lactate produced in muscles |
-exported from muscles
-carried to liver by blood
-converted to pyruvate
-oxidized by TCA cycle or reconverted to glucose thru gluconeogenesis |
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mcs5109 Thu, 28 Jan 2010 06:38:37 GMT |
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| alcoholic fermentation |
-under anaereobic a=conditions in yeast
-NAD+ is regenerated
-produces EtOH and CO2 in 2 rxns:
1. pyruvate decarboxylase (contains TPP)
2. alcohol dehydrogenase |
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mcs5109 Thu, 28 Jan 2010 06:38:37 GMT |
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| homolactic fermentation |
-occurs when muscle very active
-O2 has been depleted
-lactate dehydrogenase oxidizes NADH via pyruvate to yield NAD+ and lactate |
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mcs5109 Thu, 28 Jan 2010 06:38:37 GMT |
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| 2 types of anaerobic replenishment |
1. Lactic acid fermentation (in muscle with no O2)
2. Alcoholic fermentation (in yeast with no O2)
-both regenerate NAD+ |
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mcs5109 Thu, 28 Jan 2010 06:38:37 GMT |
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| Regeneration of NAD+ anaerobically |
-NAD+ is replenished by the reduction of pyruvate
-no O2
-must resolve glycolysis with no net oxidation of carbon fuel compounds
-called "fermentation"
-lactic acid fermentation
-alcoholic fermentation |
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mcs5109 Thu, 28 Jan 2010 06:19:36 GMT |
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| Regeneration of NAD+ aerobically |
-NADH passed into mito for re-oxidation
-respiratory chain: NADH reduces O2 to H2O via e- transfer and oxidative phosphorylation
-in muscle |
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mcs5109 Thu, 28 Jan 2010 06:01:58 GMT |
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| Problem with NADH |
Coenzyme NAD+ is limiting, and must be regenerated from NADH |
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mcs5109 Thu, 28 Jan 2010 06:00:44 GMT |
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| Overall rxn of glycolysis |
glucose + 2 ADP + 2 Pi + 2 NAD+ --> 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O |
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mcs5109 Thu, 28 Jan 2010 05:39:33 GMT |
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| How does a partial deficiency of hexokinase affect ability of RBCs to transport oxygen? |
-lower [glycolytic intermediates] b/c hexokinase catalyzes 1st rxn
-lower 2,3-BPG []
-increased Hb oxygen affinity
-person doesn't get as much O2 |
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mcs5109 Thu, 28 Jan 2010 05:36:43 GMT |
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| How 2,3 BPG influences O2 transport |
-2,3 BPG specifically binds to deoxy Hb
-RBCs synthesize and degrade 2,3 BPG via detour from glycolysis |
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mcs5109 Thu, 28 Jan 2010 05:36:43 GMT |
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| Fundamental difference b/w Class I and II Aldolases |
-Class I mechanism in notes
-Class II mechanism does not form Schiff base
-instead, a divalent Zn+2 or Fe+2 polarizes the carbonyl oxygen to stabilize enolate intermediate |
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mcs5109 Thu, 28 Jan 2010 05:04:27 GMT |
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| Class II Aldolase |
-in fungi, plants
-no Schiff base
-Zn+2 or Fe+2 polarize carbonyl oxygen of substrate to stabilize enolate intermediate |
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mcs5109 Thu, 28 Jan 2010 05:04:27 GMT |
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| Class I Aldolase |
-in animals and plants
-mechanism in notes
- |
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mcs5109 Thu, 28 Jan 2010 05:04:27 GMT |
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| *How does hexokinase prevent wasteful hydrolysis of ATP? |
-HK catalyzes the transfer of a phosphate group from ATP to glucose to yield GP6, but not to water to yield ADP and Pi
-water can fit in active site!
-glucose induces large conformational change in HK
-like closing jaws on glucose
-places ATP closely to proper -OH of glucose and excludes H2O from the active site
-substrate-induced conformational change in HK is responsible for the enzyme's specificity
-undergo conformational changes upon binding their substrates |
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mcs5109 Mon, 25 Jan 2010 01:55:51 GMT |
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| *2 major differences between hexokinase and glucokinase |
1. HK is non-specific (catalyzes D-glucose, D-fructose, D-mannose) Its Km is 10-20 microM.
2. Glucokinase (aka Hexokinase D) is the predominant isozyme of hexokinase in the liver. It is specific for glucose. Its Km is 10mM. |
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mcs5109 Mon, 25 Jan 2010 01:33:01 GMT |
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| *Why is Mg+2 absolutely required for kinases? |
Mg+2 functions to shield - charged groups of ATP, making the phosphorous atom more accessible for nucleophilic attack of the -OH of glucose. |
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mcs5109 Mon, 25 Jan 2010 01:47:41 GMT |
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| Why are metal ions good? |
-act like H+ to neutralize - charge
-act as Lewis acids
-more effective catalysts than H+ b/c can be present at high []s at neutral pH and can have more than one + charge |
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mcs5109 Mon, 25 Jan 2010 01:12:47 GMT |
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| alcohol dehydrogenase contains ___. |
contains Zn+2 which functions to polarize the carbonyl group of acetylaldehyde |
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mcs5109 Mon, 25 Jan 2010 01:12:47 GMT |
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| TPP stands for__________. It is a derivative of __________. It is required for the enzyme __________ because _____________. |
-thiamine pyrophosphate
-a derivative of vitamin B1
-required because decarboxylation of an alpha-keto acid such as pyruvate requires buid-up of - charge on teh carbonyl carbon in TS. |
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mcs5109 Mon, 25 Jan 2010 01:10:32 GMT |
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| pyruvate decarboxylase info |
-contains tightly, non-covalently associated coenzyme TPP |
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mcs5109 Mon, 25 Jan 2010 00:52:20 GMT |
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| Which organisms is pyruvate decarboxylase present in? |
not in animals |
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mcs5109 Mon, 25 Jan 2010 00:52:20 GMT |
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| What is the fate of lactate made in muscle cells? |
-exported from muscles
-carries by blood to liver
-converted to pyruvate and oxidized by TCA cycle
-or, reconverted to glucose via gluconeogenesis |
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mcs5109 Mon, 25 Jan 2010 00:52:20 GMT |
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| Is lactate dehydrogenase stereo-specific? What does it make? |
yes--> creates L-Lactate |
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mcs5109 Mon, 25 Jan 2010 00:38:32 GMT |
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| alcoholic fermentation occurs in _______________. It uses the enzyme _______________. |
yeast
pyruvate decarboxylase |
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mcs5109 Mon, 25 Jan 2010 00:38:32 GMT |
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| lactic acid fermentation occurs in ____________. It uses the enzyme _______________. |
muscle
lactic dehydrogenase |
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mcs5109 Mon, 25 Jan 2010 00:38:32 GMT |
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| 2 processes of anaerobic replenishment |
1. lactic acid fermentation
2. alcoholic fermentation |
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mcs5109 Mon, 25 Jan 2010 00:38:32 GMT |
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| overall rxn of anaerobic glycolysis |
glucose + 2 ADP + 2 Pi --> 2 lactate + 2 ATP + 2 H2O |
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mcs5109 Mon, 25 Jan 2010 00:38:32 GMT |
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| 2,3- biphosphoglycerate |
-present in RBCs
-binds with greater affinity to deoxygenated hemoglobin
-2,3-BPG stabilizes the T state of deoxy Hb, making it harder for oxygen to bind to Hb
-helps O2 release to tissues |
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mcs5109 Sun, 24 Jan 2010 04:35:58 GMT |
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| mutase |
enzyme transfers a functional group from one position to another on the same molecule |
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mcs5109 Sun, 24 Jan 2010 04:35:58 GMT |
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| 1,3-biphosphoglycerate is a mixed ___________ between ______________ and ______________. |
-anhydride
-carboxylic acid
-phosphoric acid |
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mcs5109 Sun, 24 Jan 2010 04:35:58 GMT |
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| How many -'s are on ATP? |
4 |
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mcs5109 Sun, 24 Jan 2010 04:35:58 GMT |
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| What steps produce ATP? |
7. Phosphoglycerate kinase (makes 2)
10. pyruvate kinase (makes 2) |
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mcs5109 Sun, 24 Jan 2010 04:12:04 GMT |
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| Which rxn is one of catalytic perfection? What is it limited by? |
5. triose phosphate isomerase
[dihydroxyacetone phosphate] |
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mcs5109 Sun, 24 Jan 2010 04:09:32 GMT |
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| catalytic perfection |
enzyme produces products as fast as they collide |
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mcs5109 Sun, 24 Jan 2010 04:09:32 GMT |
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| rate limiting rxn in glycolysis |
3. phosphofructokinase |
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mcs5109 Sun, 24 Jan 2010 04:09:32 GMT |
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| Mg+2 |
-required for kinase activity
-shields - charges of ATP to facilitate nucleophilic attack of glucose on gamma-phosphate of ATP |
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mcs5109 Sat, 23 Jan 2010 07:00:40 GMT |
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| hexokinase can operate on... |
...glucose, D-mannose, D-fructose |
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mcs5109 Sat, 23 Jan 2010 07:00:40 GMT |
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| Km of hexokinase vs. glucokinase |
Hexo- 10-20 microM
Gluco- 10 mM |
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mcs5109 Sat, 23 Jan 2010 07:00:40 GMT |
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| glucokinase |
-aka hexokinase D
-predominant isozyme of hexokinase in the liver
-Km= 10mM |
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mcs5109 Sat, 23 Jan 2010 07:00:40 GMT |
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| Glycolysis Step 1 enzyme and mechanism |
-Hexokinase
-nucleophilic substitution |
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mcs5109 Sat, 23 Jan 2010 07:00:40 GMT |
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| NADH is a __________ power. |
-reducing |
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mcs5109 Sat, 23 Jan 2010 06:16:51 GMT |
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| Net Profit of Glycolysis |
-2 ATP
-2 NADH
-2 pyruvate |
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mcs5109 Sat, 23 Jan 2010 06:16:51 GMT |
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| Phase 1 begins with the molecule ______________. Phase 2 begins with x_____________. |
-glucose
-2 glyceraldehyde-3-phosphates |
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mcs5109 Sat, 23 Jan 2010 06:23:21 GMT |
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| Phase 2 of Glycolysis is called the ________________. It creates x_____________. |
-Energy Generation or Payoff phase
-4 ATPs |
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mcs5109 Sat, 23 Jan 2010 06:16:51 GMT |
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| Phase 1 of Glycolysis is called the ________________. It uses x__________. |
-Preparatory or Investment phase
-2 ATPs |
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mcs5109 Sat, 23 Jan 2010 06:16:51 GMT |
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| substrate-level phosphorylation |
Couple hydrolysis of super-high-energy compounds to ATP synthesis |
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mcs5109 Sat, 23 Jan 2010 06:16:51 GMT |
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How many high energy compounds are in glycolysis?
What are they? |
6. 1,3 bisphosphoglycerate
9. Phosphoenolpyruvate (PEP) |
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mcs5109 Sun, 24 Jan 2010 04:10:39 GMT |
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| *Chemical Strategy of Glycolysis |
1. Add phosphoryl group to glucose
2. Convert phosphorylated intermediates into compounds with high phosphate group-transfer potentials ("super high energy compounds"
3. Couple hydrolysis of super-high-energy compounds to ATP synthesis (substrate-level phosphorylation) |
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mcs5109 Mon, 25 Jan 2010 00:05:30 GMT |
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| anaerobic alcoholic fermentation occurs in ___________ and uses x ________ to create x ___________ molecule(s). |
-yeast
-2 NADH
-2 CO2 and 2 ethanol |
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mcs5109 Sat, 23 Jan 2010 06:02:13 GMT |
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| Aerobic oxidation goes through ____________, uses x__________, goes through _______________, and creates x_____________. |
-the citric acid cycle
-2 NADH
-oxidative phosphorylation
-6 CO2 and 6 H2O |
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mcs5109 Sat, 23 Jan 2010 06:01:15 GMT |
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| anaerobic homolactic fermentation occurs in ___________ and uses x ________ to create x ___________ molecule(s). |
-muscle
-2 NADH
-2 lactate |
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mcs5109 Sat, 23 Jan 2010 06:01:15 GMT |
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| Fermentation |
-energy metabolism with no net oxidation of the fuel compounds |
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mcs5109 Sat, 23 Jan 2010 06:01:15 GMT |
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| Why glycolysis? |
-central role
-used by most organisms
-very ancient (developed before lots of O2 in air)
-1st metabolic pathway to be understood |
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mcs5109 Sat, 23 Jan 2010 06:01:15 GMT |
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