Biological Sciences Questions | Assignment

Biological Sciences
1. In a cell, why must NADH be reoxidized? How does this happen in an organism that uses
respiration? Fermentation?
NADH molecule is reoxidized to enable the process of glycolysis of freshly formed glucose.
Reoxidization happens to support the next round of the glycolysis process. Reoxidization of
NADH happens in the organism that uses respiration is based on the type of respiration used
by the particular organism. The organism using aerobic respiration continues the aerobic
citric acid cycle when there is an ample amount of oxygen. In a condition of lack of oxygen,
the organism shifts the process of respiration into anaerobic respiration. Fermentation is said
to be the process of complex substance breaking down into a simple substance.
2. Explain the chemiosmotic mechanism of ATP generation. How does oxidative
phosphorylation compare with substrate-level phosphorylation found in glycolysis and the
Kreb’s cycle?
ATP is created due to the formation of the proton gradient in the membranes of mitochondria.
The mechanism of chemiosmotic is regulated by certain components which are proton pump,
proton gradient and ATP synthase. Oxidative level phosphorylation occurs when ATP is
formed due to the oxidation of NADH and FADH2. It also happens due to the frequent
transportation of the electrons and protons. Substrate level phosphorylation occurs during the
process of phosphorylation when the phosphorylating ADP together with the phosphate and
power offered as the result of the dual reaction. The process of Substrate level
phosphorylation happens outside the mitochondria. This process may take place inside the
mitochondria. During the process, Substrate level phosphorylation which is taking place
outside of cell happens during glycolysis. Substrate level phosphorylation that takes place
inside the mitochondria happens during a citric acid cycle which is also termed as Kerbs
cycle.