Anaerobic Respiration

This content is also copied from our biology textbook. Nelson Biology 12.

If the oxygen is not available, we wouldn't be able to continue glycolysis. One method involves transferring the hydrogen atoms of NADH to certain organic molecules instead of the electron transport chain. This process is called Fermentation.

Bacteria - Ethanol Fermentation


Fig. 1 Ethanol fermentation creates ehtnaol and carbon dioxide from glucose, In this process, NADH is oxidized to NAD+, allowing glycolysis to continue

Eukaryotes (Human, animal) - Lactate (Lactic acid) Fermentation.

Figure 2. Lactate fermentation produces lactic acid from glucose. inthe process, NADH is oxidized to NAD+, allowing glycolysis to continue.

This process is much more effective than ethanol fermentation because in this process, the pyruvate is directly converted into lactate whereas ethanol fermentation requires extra energy to covnert pyruvate into 2 Acetaldehyde. When the Lactate is accumlated in your muscle, it causes stiffness, soreness, and fatigue but once the enough oxygen is provided to blood, it is converted back into pyruvate then goes back through the kreb cycle.

C4 vs CAM plants

This content is all from grade 12 biology text book in A.Y Jackson S.S
Nelson biology 12

C4 vs CAM plants

C4 photosyntehsis - a photosynthetic pathway of carbon fixation that reduces the amount of photorespiration that takes place by continually pumping CO2 molecules (via malate) from mesophyll cells into bundel-sheat celss, where rubisco brings them into the C3 Calvin cycle

- Sugar cand and corn, member of grass faimly, are examples of C4 plants
- In this process, an enzyme called phosphenolpyruvate carboxylase first catalzyes the addition of a Co2 molecule to a three-carbon molecue called phosphenolpyrubvae (PEP), forming four-carbon molecue oxaloacetate (OAA). This is why hte process is called C4 photosynthesis or the C4 pathway.
-The C4 patheway uses almost twice as much ATP as the C3 pathway to produce glucose, but without this mechanism, photorespiration would reduce the glucose yield to less than half that produced by the C3 pathway.
-Key words to know ' Oxaloacetate/Plasmodesmata/PEP/

*This process is advantageous in hot tropical climates where photorespiration would otherwise convert more than half of the glucose prodcued back to CO2




Crassulacean acid metabolism (CAM) - a photosnythetic mechanism in which stomata open at night so that plants can take in CO2 and incorporate it into organic acids, and close during the day to allow the organic acids to release CO2 molecules that enter C3 Calvin cycle to be fixed into carbohydrates.

-Water-storing plants (known as succulents) such as cacti and pineaaples, are examples of CAM plants
-Closing stomamta during the day helps conserve water but prevents CO2 from entering the leaves. In the dark, when stomamta open, the plants take in CO2 and incoporate it into C4 organic acids using the enzymes PEP carboxylase.
-This occurs in a hot,dry and desert environment.

Comparison
1) In C4 plants, such as sugar cane, Co2 is first incoprated into C4 organic acids in mesophyll cells. The C4 organic acids enters bundle-sheath cells throguh cell-cell conncetions and then releases carbon dioxide, which is fixed via the Calvin cycle.
2) IN CAM plants, such as pineapples, carbon fixation into organic acids occurs at night, and the Clavin cycle occurs in the day.