<h2>MAPK signalling </h2>
Explanation:
MAPK stands for mitogen activated protein kinase
- Ras-MAPK pathway includes cell division and differentiation
- All growth factors which induce cell division transfer their signal by Ras-MAPK pathway
- Ras-MAPK pathway starts with the binding of insulin hormone to receptor and autophosphorylation on its own tyrosine residue
- Phosphotyrosine residue of receptor recognized by a scaffold protein called insulin receptor substrate(IRS-1)
- Phosphotyrosine residue of IRS-1 recognized by a signaling protein called Grb2
- Grb2 binds to the phosphotyrosine of IRS-1 and provides binding site for SOS protein
- SOS binds to Grb2,then to Ras and act as guanosine exchange factor causing exchange of GDP to GTP on Ras protein
- Ras is a monomeric protein and activated Ras binds to kinase protein and activate it through phosphorylation which further leads to initiation of cell division
- If cells are injected with a non-hydrolyzable form of GTP then Ras would be active all the time which will lead to uncontrolled cell division(cancer)
Answer:
B. The theory cannot be tested through direct observation.
Explanation:
Answer: A
Explanation: Humans shiver when its cold, even if your using a blanket you still shiver.
Answer:
<u>Negative Feed Back system -</u> " Some times an organ stops or interrupts a process or function in order to stabilize its self and the body, mainly the output or product of the process is lessened in order to control the situation such mechanism is known as negative feed back system."
Explanation:
<u>Negative feedback system in Lungs </u>
Now in lungs, the respiratory system maintains the normal partial pressure of the arterial oxygen and Carbon dioxide. As the partial pressure if exerted by them has a very high influence on the blood pH and can cause imbalance in the blood pH. So for this reason the negative feed back system is present.
As the body sends the message to the controlling hub of human body and then it starts the process of stabilizing the whole system back to normal by rearrangements of components or parts, along with secretion of some chemicals in the human body.
<em>Moreover a sketch is drawn which shows the feedback mechanism in a more simple way.</em>