Just changed and transferred
Answer:
Explanation:
A. Cancer cells are cancerous because they divide all the time. Normal cells stop dividing once there's enough of them but cancer cells divide when not required as well. Therefore, if Ras is mutated it will always be "on" which means it will activate the pathway which will lead to division of cells i.e. cells divide to multiply their numbers so more cells will be made. Normally, cells only multiply whne there's the growth factor present to activate the whole pathway, but since Ras is mutated it doesnt need the growth factor to activate the pathway, it automatically always activates the pathway even in absence of growth factor.
B. It is highly unlikely that the proposed drug will have a useful effect. This is because mutant Ras protein of this type behaves as though it is constantly "on". Ras acts downstream of the receptor, i.e. first you have the reception of growth factor in receptor, then the ras gets activated. However, the activating mutation makes its effect felt (Ras is activated no matter if there's a growth factor or not), which is why mutant Ras is always active and no longer dependent on the receptor for activation.
Therefore, blocking the ability of the receptor to dimerize and activate Ras will probably not have an effect on cells containing the mutant Ras protein as it does not inhibit the activity of mutated Ras protein.
(Check out the Ras/Ref/MEK/Erk pathway for better understanding of how significant role Ras protein plays in cell proliferation i.e. division)
The exchange of oxygen, food, and waste between mother and fetus occur in the placenta.
Answer:
Two reasons are that the grasses they ate disappeared which caused some to die, but some lived and ate from trees and reproduction and such happened.
Explanation:
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