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CPBiology IntroductiontoGenetics Name_____________________________________ Date_____________________ Review:IntroductiontoGenetics Meiosis 1. What is the meaning of diploid number and haploid number? Name some examples of human cells that are diploid and human cells that are haploid? Diploid means at least one copy of one chromosome from each parent (mom and dad). Haploid means at least one copy of one chromosome from either parent (mom or dad). Sex cells are the only cells in the body that are haploid (eggs and sperm). All the rest are diploid. 2. For cats, the normal chromosome number in a body cell is 38 chromosomes. What is the haploid chromosome number? 19 3. Why does meiosis produce daughter cells different from the parent cell? The daughter cells are haploid, whereas the parent cells are diploid. Also, crossing over and independent assortment take place, which both change the genetic makeup of the daughter cells. 4. Define gonad. Provide examples of gonads. The reproductive organ. In males the gonads are the testes. In females the gonads are the ovaries. 5. Define gamete. Provide examples of gametes. Reproductive or sex cell. In males the gametes are sperm. In females the gametes are eggs. CPBiology IntroductiontoGenetics 6. Explain how fertilization restores the normal number of chromosomes to an organism. You may use a diagram to help you. A haploid egg plus a haploid sperm produces a diploid zygote. The organism’s diploid number is its normal chromosome number. (Insert drawing of sperm fertilizing egg to make zygote here, as drawn in POGIL) 7. What is crossing over? When in meiosis does it happen? What does crossing over do to the genetic information contained in cells? Crossing over is when parts of homologous chromosomes are exchanged during meiosis. It happens during Prophase 1. It increases the genetic variation in the gametes, because parts of the mother chromosomes have been exchanged with the father’s chromosomes. 8. How many chromosomes are in a human diploid cell? How many chromosomes are in a human cell produced by meiosis? 9. How do the parent cells compare to the cells produced at the end of meiosis II? 46 23 The cells at the end of meiosis 2 have half the number of chromosomes as the parent cells at the beginning of meiosis. 10. Why are the offspring of organisms that reproduce sexually NOT genetically identical to either of the parents? Crossing over and independent assortment in Prophase 1 make the offspring genetically different from their parents. This sorting and recombination of genes makes the offspring not genetically identical to either parent. CPBiology IntroductiontoGenetics 11. List all the phases of meiosis and describe what happens in each phase. See Meiosis worksheet, question 11 12. What is nondisjunction? What impact does nondisjunction have on a zygote produced from an egg or sperm that underwent nondisjunction? Nondisjunction is when homologous chromosomes fail to separate, either in anaphase 1 or anaphase 2 in meiosis. The consequence of this lack of separation is that the zygote formed from these gametes could have too many chromosomes or too few, depending on which gamete formed the zygote. (See errors in meiosis notes for visual) CPBiology IntroductiontoGenetics FertilizationandDevelopment 13. What is fertilization? Where does it take place in humans? Fertilization is the union of egg and sperm to produce a zygote. In humans it takes place in the fallopian tubes 14. Draw a diagram of fertilization. Be sure to label egg, sperm and zygote. 15. What is a zygote? How many cells are there in a zygote? A zygote is a fertilized egg. A zygote consists of only one cell. 16. Explain the term cleavage. Cleavage is a rapid series of mitotic (mitosis) divisions early on in the development of an embryo. 17. What is differentiation? In what stage of development does differentiation occur? Why is it important for cells in an embryo to differentiate during development? Differentiation is when each cell gets its particular job. Differentiation takes place during the gastrula stage of development. If differentiation did not occur, the embryo would not develop into the complex organism it needs to be. CPBiology IntroductiontoGenetics 18. List the organ system(s) in each layer in a gastrula is responsible for creating: a. Ectoderm Skin, nervous system b. Mesoderm Skeleton, muscles, circulatory system, reproductive system c. Endoderm Digestive tract, respiratory system, liver, pancreas, bladder MendelianGenetics 19. Know the vocabulary related to Mendelian genetics, as defined from the textbook. 20. Be able to do each of the types of Punnett squares we did in class. These include: a. Complete/Simple dominance b. Incomplete dominance c. Codominance d. Multiple alleles (blood type problems) e. X-linked inheritance