Question

CHAPTER 12 THE CELL CYCLE Study Questions The Key Roles of Cell Division 1. Why do cells divide? 2. What are the major events of eukaryotic cell division that enable the genome of one cell to be passed on to two daughter cells? 3. How do chromosomal numbers change throughout the human life cycle? The Mitotic Cell Cycle 4. What are the phases of the cell cycle? What is the sequence of events that occurs during each phase? 5. What are the phases of mitosis? What are the characteristic events of each phase? 6. What is the function of the mitotic spindle? What elements compose the mitotic spindle in animals? 7. What changes in the mitotic spindle during each phase of mitosis? 8. How do motor proteins associated with the kinetochore microtubules bring about the poleward movement of chromosomes? 9. How is cytokinesis in animals and plants similar? How is it different? Regulation of the Cell Cycle 10. What are the roles of checkpoints, cyclin, Cdks, and MPF in the cell cycle control system? 11. What internal and external factors influence the cell cycle control system? How do each do so?

Answer 1

1. The cell division is the characteristics of a living cell where a parent cell divides to form the two daughter cell. This helps to increase the cell number at a particular time.

2. The cell division of eukaryotic cells is divided into two phases- karyokinesis and cytokinesis. In karyokinesis, there is a division of nucleus that is the genome and includes four phases- prophase, metaphase, anaphase, and telophase. In prophase nuclear membrane gets disappeared and the chromatin gets condensed. In metaphase, genetic information carrying chromosome align at the equator at the metaphase plate. In anaphase, the chromosomes divide and get segregated as two daughter nuclei. In telophase, there is separation of the nucleus and two complete nucleus forms.

3. Chromosome numbers remain same throughout the human life except at the formation of gametes. During gamete formation by meiosis, there is haploid set of chromosomes but in all the other body cells there is diploid chromosomal set throughout life.

4. There are mainly two phases Interphase and the M phase. In interphase the stages are G1, S, G2. Then there is M phase which includes karyokinesis (prophase, metaphase, anaphase and telophase) and then cytokinesis.