dongs I think is your answer
Answer:
Explanation:
a is always true no matter what
I cannot found the exercise anywhere, so I will just explain how the toxin works.
A toxin is a toxic substance made by a living organism such as a bacterium, a fungus, a plant or an animal.
Labil toxins are toxins which are by easily degraded. among these toxins, there is the toxin of Escherichia coli and the cholera toxin of <span>Vibrio cholerea.
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The intracellular target of cholera toxin is adenylate cyclase, one of the most important eukaryotic cell regulatory systems. This enzyme is involved in the conversion of ATP into a cyclic AMP (cAMP), a crucial intracellular messenger in a wide variety of cellular processes.
Cholera toxin catalyzes the transfer of ADP-ribose from NAD (Nicotinamide Adenine Dinucleotide) to a specific arginine residue of the Gsa protein, resulting in the activation of adenylate cyclase and consequently the increase of the intracellular level cAMP. AMPc activates a cAMP-dependent protein kinase, which leads to phosphorylation of the protein, modification of ion transport and finally diarrhea.
Geological change will not cause a mass extinction, because it happens on a too big scale - on the scale of millions of years. During such long time, it is more likely that other causes will influence the survival of extinction of species, such as climate change or environmental disasters, and even if there is a small influence, it would not be significant next to other causes.
