Question

1. Most people who are completely blind have circadian rhythms that are “free running”; that is, their circadian rhythms are not synchronized to their environment time cues and they oscillate on a cycle of about 24.5 hours. Why do you suppose the circadian clocks of blind people are not entrained to the same 24-hour clock as the majority of the population? Can you guess what symptoms might be associated with a free-running circadian clock? Do you suppose that blind people have trouble sleeping?

2. When cells enter mitosis, their existing array of cytoplasmic microtubules has to be rapidly broken down and replaced with the mitotic spindle, which pulls the chromosomes into the daughter cells. The enzyme katanin, named after Japanese samurai swords, is activated during the onset of mitosis and cleaves to microtubules into short pieces. What do you suppose is the face of the microtubule fragments created by katanin?

Answer 1

1.The circadian clocks of blind people are not entrained to the same 24-hour clock as the majority of the population because our internal clock gets all the hints from seeing light and in case of blind people, this is not possible.The symptoms that might be associated with a free-running circadian clock is not adjusted sleep patterns naturally as well as artificially.Yes,blind people face sleep troubles as with the inability to perceive light, they face continual circadian desynchrony that results  in poor sleep and daytime dysfunctioning as well.

2.Katanin functions to break the  microtubules along their length but the breaks are at positions that are far away from their GTP caps. The fragments that result after breakage consists of the GDP-tubulin exposed at the ends and therefore the framents undergo depolymerization quickly.. Katanin thus quickly destroys the microtubules that exist.