pathways that reduce nad+ to nadh how do cells transfer electrons from food to nad+ to make nadh?...
TRANSCRIPT
![Page 1: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/1.jpg)
Pathways that reduce NAD+ to NADH
• How do cells transfer electrons from food to NAD+ to make NADH?– From sugars– From proteins– From fatty acids
Images are from Wikimedia Commons unless otherwise indicated
![Page 2: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/2.jpg)
Oxidation of glucose to CO2
http://www.biologie.uni-hamburg.de/b-online/e19/19d.htm
Glycolysis Pyruvate oxidation
Citric acid cycle
![Page 3: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/3.jpg)
Glycolysis: partial oxidation of glucose to pyruvate
![Page 4: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/4.jpg)
Glycolysis – in cytoplasm of all cells
1. Uses 2 ATPs to “activate” glucose
2. Splits glucose into two 3-carbon sugars
3. Partially oxidizes the sugars, yielding 2 NADH per glucose
4. Substrate-level phosphorylation of ADP to make 4 molecules of ATP
5. Nets 2 pyruvates, 2 ATP, 2 NADH
![Page 5: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/5.jpg)
In respiring cells, pyruvate is oxidized to CO2 + acetyl CoA
Two molecules of pyruvate are oxidized to 2 acetyl CoA + 2CO2, generating 2 NADH per molecule of glucose.
http://www.micro.siu.edu/micr201/chapter8N.html
![Page 6: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/6.jpg)
Citric acid cycle generates ATP, reduced electron carriers and oxidizes acetate to CO2
Campbell & Reece Biology 8th ed.
![Page 7: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/7.jpg)
![Page 8: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/8.jpg)
Fats and proteins
http://www.life.umd.edu/classroom/bsci424/BSCI223WebSiteFiles/GeneralCatabolism.gif
http://www.ruf.rice.edu/~bioslabs/studies/mitochondria/mitokrebs.html
![Page 9: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/9.jpg)
Locations of eukaryotic energy pathways
Campbell & Reece Biology 8th ed.
![Page 10: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/10.jpg)
Respiring cells make most of their ATP via oxidative phosphorylation. What happens in the absence of respiration (no electron transport chain function)?
![Page 11: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/11.jpg)
Fermentation reduces pyruvate to lactic acid or ethanol, to regenerate NAD+ from NADH
2 ADP + 2 Pi 2 ATP
Glucose Glycolysis
2 NAD+ 2 NADH
2 Pyruvate
+ 2 H+
2 Acetaldehyde2 Ethanol
(a) Alcohol fermentation
2 ADP + 2 Pi2 ATP
Glucose Glycolysis
2 NAD+ 2 NADH+ 2 H+
2 Pyruvate
2 Lactate
(b) Lactic acid fermentation
2 CO2
![Page 12: Pathways that reduce NAD+ to NADH How do cells transfer electrons from food to NAD+ to make NADH? –From sugars –From proteins –From fatty acids Images](https://reader035.vdocuments.mx/reader035/viewer/2022062409/5697bfd91a28abf838caf92e/html5/thumbnails/12.jpg)
In the absence of respiration
• Cells can make ATP through glycolysis and fermentation of glucose
• Cells cannot run pyruvate oxidation or citric acid cycle (no mitochondrial function in eukaryotes)