Cell Processes: Mitosis and Meiosis – Teacher’s Guide
Kit # 3674-07
Part 2 assessment questions 1. How does meiosis lead to genetic variability within a population? Use S. fimicola as an example.
Meiosis leads to genetic variability through the segregation of gene alleles, the independent assortment of genes, and crossing-over, as well as the variability that results from the combination of the genetic material from the gametes of two genetically different individuals.
2. How does genetic variability represent an adaptive advantage for organisms that reproduce sexually?
With increased variability among individuals in a population comes an increased probability that the population would be able to survive under changing environmental and evolutionary pressures. This ability, in turn, gives the species a better chance of surviving and thriving in the future.
3. Why is S. fimicola an ideal organism for the demonstration of crossing-over?
The fact that it displays both haploid and diploid stages of reproduction allows scientists to easily manipulate different strains of the organism. The colored ascospores are easily identified and the ascospore patterns readily indicate when crossing-over has occurred.
4. Research cell division in prokaryotic and eukaryotic cells, compare and contrast the characteristics of mitosis in each.
Unlike eukaryotic cells, prokaryotic cells utilize neither mitosis nor meiosis. Prokaryotic cells replicate through a process known as binary fission. The prokaryotic DNA, which is found free in the cell and not confined in a membrane-bound nucleus, replicates and each copy attaches to a different part of the cell’s plasma membrane. The cell grows and, when it is approximately double its original size, the membrane grows inward, dividing the cell into two genetically identical daughter cells.
5. Using what you know about mitosis, genetic transcription, cell cycle, and the two karyotype images answer the following questions:
How do cells ensure DNA replication is accurate?
The DNA polymerase has a 3’---5’ exonucluease domain. This domain is responsible for proofreading the DNA and reads in the opposite direction of DNA replication.
According to the images, on which chromosomes did the mutation occur? By which mechanism of cell replication do you think the Philadelphia chromosome occurs? Explain.
????
Assuming that it takes an average of 12 hours for CML cells to complete the cell cycle, how many cells will be produced within a week (7days)?
4,096 cells will develop in one week (168 hours/week)
Would you agree that cancer is the disease of mitosis? Explain.
Answers will vary, but the students should be strongly considering cancer as a disease of mitosis.
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