If a somatic cell from a cat contains 40 picograms of DNA during G2 of interphase, how many picograms of DNA would be present in each cell during metaphase II of meiosis? (Enter the number only, not the units.)
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 meiosis? 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?
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Clarify Question
· What is the key concept addressed by the question?
o The question asks about the amount of DNA in a cell at different stages of meiosis.
· What type of thinking is required?
o You are being asked to analyze the amount of DNA present at different stages of meiosis.
· What key words does the question contain and what do they mean?
o 40 picograms of DNA in G2 – a cell in G2 will have already gone through S phase so it will not gain any more DNA. In moving to metaphase II the cell will have gone through one division.
Gather Content
· What do you know about meiosis? How does it relate to the question?
o After G2 a cell will go through meiosis I and the amount of DNA in each cell will be cut in half. In metaphase II the cells will not have divided again.
Consider Possibilities
· What other information is related to the question? Which information is most useful?
o The chromosomes will have duplicated in S phase and divided once in meiosis I but will not have divided a second time in metaphase II.
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o The DNA has already duplicated in G2 and will go through one division in meiosis. So, if a cell had 40 picograms of DNA in G2 then after one division the cells will each have 20 picograms.
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 calculate the amount of DNA in a cell at a specific stage in 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 after G2 the cells had duplicated their DNA? Did you realize that the cells in metaphase II will have divided their DNA once?
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