生物专业英语教学-细胞的繁殖.pptVIP

Exercises I Key terms: matching Match each term on the left with the most appropriate description on the right a. DNA+histone b. two sets c. X and Y d. one set e. chromosome display f. set of microtubles g. plant division h. gamete production i. sequence of cell growth and division j. cell division k. crossing over l. inhibit cell division m. Division of cytoplasm n. single chromosome copy o. positively charged protein 1. cytokinesis 2. synapsis 3. histone 4. mitosis 5. cell cycle 6. chalone 7. spindle 8. chromatid 9. nucleosome 10. diploid 11. meiosis 12. cell plate 13. sex chromosome 14. karyotype 15. haploid I Key terms: matching II. True or false Autosomes include X and Y chromosomes. 2. Cells enter G2 at the end of the S phase. 3. Chalones promote cell division. 4. The nuclear envelope forms in telophase. 5. Plant cells have the most prominent centrioles. 6. Nuclear division may occur without cytokinesis. 7. Homologous chromosomes pair in synapsis. 8. Chromosomes break at chiasmata(交叉). 9. Sexual organisms cannot be cloned. 10. All daughter cells are hapoid. [ka??zm?t?] III Completion If human chromsomes are stained on a slide, the resulting display, which is called a karyotype, should contain twenty-two pairs of autosomes and one pair of sex chromosomes. The S in S phase stands for synthesis because during this time DNA is replicated and histones are synthesized. 3. Instead of centrioles, most plants and fungi have regions called microtubule – organizing centers. During meiosis but not during mitosis , homologous chromosomes pair up in a process of synapsis. Mitosis produces 2 progeny cells, each with a set of diploid chromosomes. III Completion 6. Meiosis produces 4 daughter cells, each with a haploid set of haploid chromosomes. 7. Microtubules called centromeric fibers attach to the chromosomes at the kinetochores 8.Two chromatids attach to each other at the centromere. IV Multiple choice 1. DNA is replicate during the__________. A. S phase