23.) Growing human cells in the laboratory in petri dish is a common research te

Question

23.) Growing human cells in the laboratory in petri dish is a common research technique. Typically, cells in culture and not all one particular stage of the cell cycle. Often, the cells are randomly distributed with respect to stage of the cell cycle. At any given moment, some cells are in G1, S, G2 or Mitosis/Cytokinesis. The number of cells in each stage at any given moment depends solely on what fraction of the average cycle time is taken up by that stage. Suppose that G1, S, G2 and Mitosis/Cytokinesis last 11 hours, 5 hours, 8 hours, and 1 hour, respectively. What percent of the cells are expected to be in each of these stages at any given moment? What percent of the cells are in interphase If prophase lasts 25 minutes, what percent of the cells are in prophase? If the amount of DNA is measured in a G2 cell and it is found to be 8 ng, how much DNA would be present in a G1 cell? How many ng of DNA would you expect to find in S phase cells? In a sperm cell?

Explanation / Answer

a. If you add all the hours up, you get 25, and you are trying to find the percentage, so it says G1 is 11 hours--this is how to set it up to get a percentage: if there are 25 hours total for cell division, and 11 hours for G1 write a fraction 11/25 and set that up to equal x over 100: 11/25=x/100 and solve and do the same for the rest. you should get: G1: 11/25=x/100 which is 44% S: 5/25=x/100 which is 25% G2: 8/25=x/100 which is 32% Mitosis/Cytokenisis: 1/25=x/100 which is 4% If you add all these up, you should get a 100%. b. G1, G2, and S are considered interphase, then it should be 96% think? not so sure c. prophase is part of the m phase, and there are x number of phases in the m phase, so since you know that the m phase is 4%, calculate 25min of that 4% just like what i showed you in a, using cross multiply. e. in the S phase, the D duplicates, so do the math.... i think 4ngX2=8ng? not sure f. i think 1ng of dna in a sperm cell because 4ng is what is found in a normal cell, and meiosis splits the DNA to four cells evenly, therefore, 4/4=1? no so sure eithe

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