If in an eight-cell embryo of an organism, the cells of the upper tier are aligned over the cells of the lower tier at a slight angle, it is likely that the organism is a vertebrate.
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Answer:
D
Explanation:
it regulates the flow of water into the cell
Answer:
e. PhoU keeps PhoR bound to the phosphate transporter protein Pst
Explanation:
PhoU is a membrane protein known to regulate the transport of phosphate (Pi) between cellular compartments. It has been discovered that mutations in this protein cause lethality because the cell becomes incapable of controlling the intracellular levels of Pi, this being toxic for the cell. PhoR is a histidine kinase/phosphatase. When the Pi level is considered to be a limiting factor, PhoR autophosphorylates at a histidine residue and then donates its phosphoryl group to PhoB. On the other hand, when the Pi level is high, this protein removes the phosphoryl group from phospho-PhoB. Finally, the Pst is a signal transduction protein that acts as a transporter capable of switching its conformation during the transport of PI.
