Friday, February 12, 2010

Got this one wrong on a quiz. Can you help? Which of the following statements is false?

1. Genes and chromosomes are duplicated during prophase





2. New nuclei are formed during telophase





3. A diploid cell will produce two diploid daughter cells by mitosis





4. Chromosomes do not pair during mitosis





5. Eash species has a specific number of chromosomes





(I said #3 and got it wrong. Is it #4???)


Thanks. BTW I would ask my instructor, but he dosen't want us to print these ?'s from online quizes because he puts them on our exam!)Got this one wrong on a quiz. Can you help? Which of the following statements is false?
During s-phase of interphase, the genetic material is duplicated. So #1 is FALSE.





Telophase sees the production of the nulear membrane. So in effect, new nuclei are formed, making #2 TRUE.





Mitosis creates two daughter cells that are diploid, because it is reproduction of somatic (body cells), no production of gametes (which would be haploid). So, #3 is TRUE





Chromosome find their homolougous pair during prophase of Meiosis, NOT mitosis. Pairing occurs during meiosis so the the gametes that are haploid can be formed. So #4 is TRUE





Each species has a specific number of chromosomes- fruit flies for example have 8 chromosomes, while humans have 46. So #5 is TRUE.Got this one wrong on a quiz. Can you help? Which of the following statements is false?
#1
The answer to this problem is #5.
2 is false.





At telophase, the two new nuclei are already formed and awaiting the rest of telophase to complete, where all cellular components are separated by actin filaments, and pullled to each pole of the dividing cell. In the middle of the dividing cell, the cell membrane starts to pinch off to finally form two new cells which are clones of each other.





Good luck. Biology... especially cell biology is a lot to remember... and even we working biologists need to review such voluminous material.
the WRONG answer is 1. Duplication of genetic material happens during the S-phase part of interphase. All of the others are true statements.
4 is my guess from my course in genetics many years ago
He, he, #5 is actually wrong, but I doubt your teacher knows that.





Robertsonian translocations have been reported in Mus musculus populations in the Madeira Island, Portugal and Sicily, Italy. They are still the same species, they just have a different 2n.


Quick abstract example: http://cat.inist.fr/aModele=afficheN%26amp;cpsidt=16610123





Also, the Squalius alburnoides complex from Portugal (Guadiana River) present different number of chromosomes (2n or 3n).





Quick abstract example (mentioning the different ploidy):


http://www.springerlink.com/content/xx566443316g2237/





Edit:


Please note that these are stable populations that maintain the number of chromossomes consatnt in each one. The occurence of Robertsonian translocations is not an isolated event that disapeares with the death of the individual (ex: Down Syndrome: a human with 47 chromossomes). There are actually stable populations of Mus musculuas ans Squalius alburnoides with different chromossome numbers.

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