RAS is a very important protein that belongs to a class of protein referred to as GTPases and plays a crucial role in switching on pathways that control cell growth, proliferation, apoptosis and differentiation and migration. For RAS to become inactive it must hydrolyze GTP to GDP which slows down the process of cell proliferation. Mutation in one copies of RAS will result to cancer because the mutated copy will permanently attach to GTP and remain in activated form which will lead to uncontrollable cell division and hence development of cancer.
#11.) Phacops. It lived in the late Devonian Period (~400 million years ago).
#12.) Carbon-14 is a good radioactive isotope for determing the age of artifacts from a burial site thought to be associated with the most recent early humans because it is present in all organic matter (which humans have, of course).
#13.) 3, Devonian.
#14.) From the Devonian Period through the Triassic Period.
#15.) Cenozoic.
Answer:
4 mass extinctions
Explanation:
as there are huge drops in the graphs
at 440,390,260,50
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