A cell biologist examines a diploid cell from a particular species of during metaphase of mitosis and determines that 8 centromeres are present. Based on this finding, how many centromeres should be present in a single cell from this species during anaphase II of meiosis?

Question

What will be an ideal response?

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

  Gather Content
  · What do you know about centromeres? How does it relate to the question?

  Consider Possibilities  
  · What other information is related to the question? Which information is most useful?

  Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?  

  Reflect on Process
  · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

4

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the number of centromeres at different stages of the cell cycle.
· What type of thinking is required?
        o You are being asked to analyze an experiment to predict how many centromeres would be present.
· What key words does the question contain and what do they mean?
        o A cell in metaphase of mitosis has 8 centromeres – this means that the diploid number of chromosomes is 8.  

  Gather Content
  · What do you know about centromeres? How does it relate to the question?
        o Centromeres are at the center of a chromosome.  They pair up during metaphase.  So if a cell has 8 centromeres in its diploid state it has 8 chromosomes.

  Consider Possibilities  
  · What other information is related to the question? Which information is most useful?
        o In anaphase II the cells will now be haploid and contain half as many chromosomes.  Each chromosome still contains one centromere.

  Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?  
        o If the diploid number is 8, the haploid number will be 4 chromosomes, each with one centromere.  Thus, the cell will have 4 centromeres.

  Reflect on Process
  · Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to analyze the results of an experiment to calculate the number of centromeres on chromosomes in cells in anaphase II of meiosis. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you recall that each chromosome contains a centromere?  Did you realize that in anaphase II of meiosis the cells would be haploid?