If a germ-line cell from a salamander contains 10 picograms of DNA during G1 of interphase, how many picograms of DNA would be present in each gamete produced by this species? (Enter the number only, not the units.)

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 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?

Answer 1

5

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 10 picograms of DNA in G1 – after S phase the cell will have 20 picograms of DNA. During meiosis the cell will go through two cell divisions, cutting the amount of DNA in half each time.

  Gather Content
  · What do you know about meiosis? How does it relate to the question?
        o After G1, a cell enters S phase and the chromosomes replicate. The chromosomes then divide twice through meiosis.   
 
  Consider Possibilities  
  · What other information is related to the question? Which information is most useful?
        o The chromosomes replicate during S phase and divide twice during meiosis, so the mass of DNA will be half as much as in G1.
   Choose Answer
  · Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?  
        o Because the DNA has duplicated after S phase the cell will have 20 picograms of DNA. After meiosis I the two daughter cells will have 10 picograms of DNA. After meiosis II the four gametes will have 5 picograms of DNA

  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 G1 the cells will duplicate their DNA? Did you realize that after meiosis two rounds of division would occur?