Chapter 16 Lecture 2
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Everything that happens in stage two is happening __. Why?
- because of the 2 3-carbon sugar
Ist gain of ATP is in what step?
the step catalyzed by phosphoglycerate kinase
3-phosphoglycerate has __.
not much potential for making ATP
3-phosphoglycerate is catalyzed by __ to 2-phosphoglycerate. In the next step, which is catalyzed by __, what happens.
The step in which phosphoenolpyruvate is catalyzed to pyruvate, what happens?
- phosphoglycerate mutase
- water is lost
- pyruvate kinase catalyzes the reaction and ATP is formed
Once 2 ATP in, everything else happens __, yet we have an __.
- input of energy
- 1) may be because there's so much substrate that caues reaction to move forward
- 2) coupling of a nonspontaneous to spontaneous reaction
Two points of the glycolytic pathway?
1) allowed capture of enough energy to let it get on inorganic phosphate
2) e- can be pumped into 3rd pathway--> ETC (only in presence of oxygen)
What are the three fates of pyruvate?
acetaldehyde (loss of CO2 and production of NAD+)--> ethanol
lactate (production of NAD+)
acetyl CoA (with loss of CO2)--> further xidation
For the alcohol and lactice acid fermentation. what is important?
- must regenerate NAD+ from NADH. Electrons go to
- 1) oxygen
- 2) molecule that regenerates NAD+
In order to get max ATP, what must happen?
in order to get MAX ATP, do it in presence of oxygen. RElease CO2 and get large amount of ATP. There are many single-celled organisms that function by anaerobic respiration
Pyruvate to ethanol pathway?
pyruvate--> acetaldehyde--> ethanol
1) pyruvate--pyruvate decarboxylase--> acetaldehyde
2) acetaldehyde--alcohol dehydrogenase--> ethanol
Pyruvate decarboxylase __
alcohol dehydrogenase __.
removes a CO2
takes electrons and uses them to reduce acetaldehyde to ethanol
What does zinc do in alcohol dehydrogenase?
polarizes substrate to accept hydride
- --> held in place by cysteine and histidine
- draw electrons towards it
What is the mechanism for lactate formation?
pyruvate--lactate dehydrogenase--> lactate
in absence of oxygen
WHat is the limiting factor in lactate fermentation?
pH as the acid builds up; not NAD+
What is a similar conformation in the dehydrogenases?
Rossman fold: a similar domain in dehydrogenase
bind NAD+ in a similar way
when NAD+ is a cofactor, this motif is involved in binding
Besides glucose, what else can be fed into the pathway?
galactose--> converted to glucose-6phosphate
6 carbon sugar entering same pathway f
1) gets phosphorylated; ATP invested * at this point, it is cleaved int o 2 three carbon sugars by fructose 1-phosphate aldolase
glyceraldehyde and DHAP are products
Glyceraldeyhde must be converted to glyceraldehyde 3-phosphate
How many ATP are invested to get from fructose to product?
2 ATP to get to the same point as part 1 of glycolysis
Going from galactose to galactose 1-phosphate, what happens?
galactokinase needs to be phosphorylated
converted it to glucose 6-phosphate
Things that can go wrong when using lactose and being lactose intolerant.
bacteria use the lactose that you can't and convert it to methane and make it painful to you
What is galactosemia?
an enzyme involved is deficient causing build up of galactose--> conveted to galactitol and draws water to tissues--> build up of water--> cataracts
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