Answer:
Option B.
Explanation:
Cystic fibrosis is caused by a defective gene which causes the lungs and the digestive system to become clogged with sticky mucus resulting the inflammation of the lungs thereby causing difficulty in breathing.
A doctor could prescribe a restricted sodium diet
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’
Answer:
The correct answer to the question: The pineal body secretes which hormone that maintains the body´s internal clock, the 24-hour wake-sleep cycle, and regulates the onset and duration of sleep?, would be, C: Melatonin.
Explanation:
The process of sleep and wakefulness, also called the circadian cycle, its a pretty complex system that is controlled by several parts of the brain, but most importantly, structures of the diencephalon (vital is the hypothalamus), the pineal gland, and the stem of the brain. All these structures, and some others, respond to changes both in light perception by the eyes and other senses, heat, and homeostatic balances. These factor play a vital role in telling the human body that it is time for sleep, or to awaken. The pineal gland, as part of this melody, is essential, as it secretes the hormone, melatonin, in response to light changes. Melatonin will balance out the process of sleep, when it is secreted in high quantities by the pineal gland, and wakefulness, when it is no longer secreted in response to the presence of light. This is what is called the circadian cycle.
