They type of RNA that does this is mRNA, messenger RNA, hence the name, it provides the message or particular genetic sequence that has been transcribed from DNA to the ribosome for which the synthesis of the polypeptide can occur.
Neural control of GFR is mediated by Sympathetic neurons that innervate alpha receptors on vascular smooth muscle causing Vasoconstriction.
<h3>How is GFR regulated?</h3>
- The sympathetic division of the nervous system regulates the GFR or Glomerular Filtration Rate.
- GFR is the sum total of filtration rates of all the working nephrons in the kidney.
- Sympathetic division comes into action when the mean arterial pressure is very low (below 80mmHg).
- In response to low blood pressure, the medulla releases norepinephrine through sympathetic nerves.
- Norepinephrine leads to activation of alpha receptors on arteries which cause vasoconstriction.
- Alpha receptors are more abundant on afferent arterioles.
- This leads to vasoconstriction (narrowing) of arteries supplying to the glomerulus.
- This decreases blood flow to glomerulus, leading to decrease in GFR.
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Answer:
a. p53 activates transcription of WAF1.
Explanation:
<u>WAF1 transcription occurs independent of p53 during oxidative stress so p53 does not play any role in cell cycle arrest in the signaling pathway which involves WAF1 . </u>
In rest of the mentioned options, p53 plays a role directly or indirectly. During double stranded lesion in DNA in G1 phase, a sensor protein known as ATM binds the DNA lesion site. ATM is a serine/threonine kinase which phosphorylates another kinase known as chk2. After phosphorylation,<u> chk2 stabilizes transcription factor p53.</u> p53 further acts as a transcription factor for the synthesis of a protein known as p21 which inhibits G1 phase specific CDK and ultimately cell is arrested in G1 phase. The cell remains in arrested state until the DNA lesion is fully repaired. <u>Hence, p53 indirectly blocks G1 to S transition with the help of p21. </u>
As such <u>WAF1 transcription factor involving pathway</u><u> </u><u>also requires p21 protein for causing cell cycle arrest but in this pathway p21 is not synthesized with the help of p53. </u>
Mitochondria is the cells <span>organelle that releases energy stored in food.</span>