Loading...

#26 BB 350 Glycolysis - Kevin Ahern's Biochemistry Online

2,369 views

Loading...

Loading...

Transcript

The interactive transcript could not be loaded.

Loading...

Loading...

Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Published on May 19, 2012

1. Contact me at kgahern@davincipress.com / Friend me on Facebook (kevin.g.ahern)
2. Download my free biochemistry book at http://biochem.science.oregonstate.ed...
3. Take my free iTunes U course at https://itunes.apple.com/us/course/bi...
4. Check out my free book for pre-meds at http://biochem.science.oregonstate.ed...
5. Course video channel at http://www.youtube.com/user/oharow/vi...
6. Check out all of my free workshops at http://www.youtube.com/playlist?list=...
7. Check out my Metabolic Melodies at http://www.davincipress.com/metabmelo...
8. Take my courses for credit (wherever you live) via OSU's ecampus. For details, see http://ecampus.oregonstate.edu/soc/ec...
9. Course materials at http://oregonstate.edu/instruct/bb350

Lecture Highlights
Glycolysis II
1. Conversion of F6P to fructose-1,6-bisphosphate (F1,6BP - need to know) is catalyzed by the enzyme phoshofructokinase (PFK) (need to know). This reaction also requires ATP and is an irreversible reaction. ATP is an allosteric effector. High levels of ATP inhibit the enzyme.
2. In the next step of glycolysis, the six carbon F1,6BP is split into two three carbon piece (DHAP and G3P) s in a reaction catalyzed by aldolase. This reaction is very unfavorable when there are equal concentrations of products and reactants. To make the reaction go forward in the cell, cells "push" (increase amounts of reactants) and "pull" (decrease concentrations of products) to make the process favorable.
3. In reaction 5, DHAP is converted to G3P, so from this step forward, there are two of each molecule.
4. Reaction 6 of glycolysis involves the only oxidation. The enzyme responsible is glyceraldehyde-3-phosphate dehydrogenase (G3PDH).
5. In reaction 7, ATP is generated in a reaction catalyzed by phosphoglycerate kinase. This reaction is referred to as a substrate level phosphorylation.
8. Reaction 8 is an isomerization catalyzed by phosphoglycerate mutase. This enzyme starts with 3-phosphopglycerate (3-PG) and converts it to 2-phosphoglycerate (2-PG). In between, an intermediate known as 2,3 BPG is made.
9. Reaction nine involves removal of a water molecule from each three carbon intermediate to form the high energy molecule called PEP.
10. Reaction 10 is the "big bang" reaction of glycolysis. It produces another ATP for each PEP and in turn, each PEP is converted to pyruvate.
11. Glycolysis is regulated by three enzymes - hexokinase (inhibited by G6P), phosphofructokinase (inhibited by ATP), and pyruvate kinase (inhibited by ATP).
12. Pyruvate is the ending point for glycolysis. Which pathway is taken from that point forward depends on the needs of the cell. Since cells have a VERY strong interest in keeping glycolysis going, the primary consideration is keeping NAD levels high.
13. Under anaerobic conditions, animals convert pyruvate to lactate using the enzyme lactate dehydrogenase (and producing NAD from NADH). Under anaerobic conditions, microbial cells undergo NON-OXIDATIVE (no electrons lost) decarboxylation (formation of CO2) to produce acetaldehyde followed by reduction of acetaldehyde by NADH to form ethanol and NAD.
14. Addition of electrons and protons to pyruvate (from NADH) creates lactate and regenerates NAD. This is important in muscles when they run low on oxygen.
15. Metabolism of glucose by anaerobic pathways does not release nearly as much energy as when glucose is metabolism by the aerobic pathway. Animals also have an alcohol dehydrogenase, but they use it for the reverse direction to break down ethanol. The product of the reverse reaction is acetaldehyde and may be responsible for hangovers.

  • Category

  • License

    • Standard YouTube License

Loading...

When autoplay is enabled, a suggested video will automatically play next.

Up next


to add this to Watch Later

Add to

Loading playlists...