<span>The fluid flows through the interventricular foramen into the third ventricle, is augmented by fluid formed by the choroid plexus of this ventricle, and passes through the cerebral aqueduct to the fourth ventricle, which also possesses a choroid plexus. The CSF from all theses sources , as well as any formed in the central canal of the spinal cord, escapes from the fourth ventricle into the subarachnoid space through the median aperture and lateral aperture.</span>
The best answer in terms of how organ cultures are an improvement on this transport method is "<span>Cultured organs can be kept alive for several weeks before transplant."</span>
Answer:
PFFT this might help? sorry if not mate
Explanation:
Cell cycle checkpoint controls play a major role in preventing the development of cancer [see Sherr, 1994, for a more detailed discussion]. Major checkpoints occur at the G1 to S phase transition and at the G2 to M phase transitions. Cancer is a genetic disease that arises from defects in growth-promoting oncogenes and growth-suppressing tumor suppressor genes. The p53 tumor suppressor protein plays a role in both the G1/S phase and G2/M phase checkpoints. The mechanism for this activity at the G1/S phase checkpoint is well understood, but its mechanism of action at the G2/M phase checkpoint remains to be elucidated. The p53 protein is thought to prevent chromosomal replication specifically during the cell cycle if DNA damage is present. In addition, p53 can induce a type of programmed cell death, or apoptosis, under certain circumstances. The general goal of p53 appears to be the prevention of cell propagation if mutations are present. The p53 protein acts as a transcription factor by binding to certain specific genes and regulating their expression. One of these, WAF1 or Cip1, is activated by p53 and is an essential downstream mediator of p53-dependent G1/S phase checkpoint control. The function of p53 can be suppressed by another gene, MDM2, which is overexpressed in certain tumorigenic mouse cells and binds to p53 protein, thus inhibiting its transcriptional activation function. Other cellular proteins have been found to bind to p53, but the significance of the associations is not completely understood in all cases. The large number of human cancers in which the p53 gene is altered makes this gene a good candidate for cancer screening approaches.
Carrier and channel proteins in the plasma membrane
are similar because they are both transport membrane proteins that allow
molecules to flow in and out of the membrane. Meanwhile, carrier protein can
further be classify as active or passive transport. These two transport
proteins makes cell’s ability to perform their functions well by maintaining a
difference between the intracellular and extracellular environment.
