Answer:
The correct answer is option E. only water-soluble hormones use second messengers.
Explanation:
Water soluble hormones can not diffuse through cell membranes as only lipid soluble molecules can pass through the cell membranes and these hormons are not lipid soluble molecules,
These water hormones are usually glycoproteins, peptide and catecholamnies such as TSH, FSH, LH and insulin. these hormones need second messengers because there receptors are present on the plasma membrane.
Thus, the correct answer is option - e. only water-soluble hormones use second messengers.
Please include the multiple choice questions and/or a photo!
Answer:
Okay
Explanation:
Human topoisomerase I plays an important role in removing positive DNA supercoils that accumulate ahead of replication forks. It also is the target for camptothecin-based anticancer drugs that act by increasing levels of topoisomerase I-mediated DNA scission. Evidence suggests that cleavage events most likely to generate permanent genomic damage are those that occur ahead of DNA tracking systems. Therefore, it is important to characterize the ability of topoisomerase I to cleave positively supercoiled DNA. Results confirm that the human enzyme maintains higher levels of cleavage with positively as opposed to negatively supercoiled substrates in the absence or presence of anticancer drugs. Enhanced drug efficacy on positively supercoiled DNA is due primarily to an increase in baseline levels of cleavage. Sites of topoisomerase I-mediated DNA cleavage do not appear to be affected by supercoil geometry. However, rates of ligation are slower with positively supercoiled substrates. Finally, intercalators enhance topoisomerase I-mediated cleavage of negatively supercoiled substrates but not positively supercoiled or linear DNA. We suggest that these compounds act by altering the perceived topological state of the double helix, making underwound DNA appear to be overwound to the enzyme, and propose that these compounds be referred to as ‘topological poisons of topoisomerase I’
Cells specialize to form specific tisue and organs because all cells have the same DNA. stem cells can develop into every type of cell inside the body.The cell is the basic unit of structure and function in all living organisms.
Vet tech assistant obtain and record patient case history, collect specimens, and perform lab procedures/equipment for surgery.
