This chapter distinguish between the following terms: somatic cell and gamete, autosome and sex chromosomes, haploid and diploid; describe the events that characterize each phase of meiosis; describe three events that occur during meiosis I but not mitosis; name and explain the three events that contribute to genetic variation in sexually reproducing organisms. | Warm up Compare sexual to asexual reproduction. What are homologous chromosomes? Describe what major processes occur during a sexual life cycle. Warm up Describe what occurs during crossing over. What are 3 sources of genetic variation? Mitosis, Meiosis, or Both? Chromosomes line up at metaphase plate Crossing over Cytokinesis Chromosomes are replicated Four haploid daughter cells result Two diploid daughter cells result Chapter 13: Meiosis & Sexual Life Cycles What you must know The difference between asexual and sexual reproduction. The role of meiosis and fertilization in sexually reproducing organisms. The importance of homologous chromosomes to meiosis. How the chromosome number is reduced from diploid to haploid through the stages of meiosis. Three important differences between mitosis and meiosis. The importance of crossing over, independent assortment, and random fertilization to increasing genetic variability. Genes: segments of DNA that code for basic units of heredity Offspring acquire genes from parents by inheriting chromosomes Types of Reproduction ASEXUAL Produces clones (genetically identical) Single parent Little variation in population - only through mutations Fast and energy efficient Eg. budding, binary fission SEXUAL Meiosis produces gametes (sex cells) 2 parents: male/female Lots of variation/diversity Slower and energy consumptive Eg. humans, trees Asexual vs. sexual reproduction Chromosomes Somatic (body) cell: 2n = 46 chromosomes Each pair of homologous chromosomes includes 1 chromosome from each parent Autosomes: 22 pairs of chromosomes that do not determine sex Sex chromosomes: X and Y Females: XX Males: XY Gametes (n=23): 22 autosomes + 1 sex chromosome Egg: 22 + X Sperm: 22 + X **or** 22 + Y Homologous Chromosomes in a Somatic Cell Karyotype: a picture of an organism’s complete set of chromosomes Arranged from largest smallest pair Making a karyotype – unsorted chromosomes 22 pairs of autosomes + 1 pair of sex chromosomes Male or | Warm up Compare sexual to asexual reproduction. What are homologous chromosomes? Describe what major processes occur during a sexual life cycle. Warm up Describe what occurs during crossing over. What are 3 sources of genetic variation? Mitosis, Meiosis, or Both? Chromosomes line up at metaphase plate Crossing over Cytokinesis Chromosomes are replicated Four haploid daughter cells result Two diploid daughter cells result Chapter 13: Meiosis & Sexual Life Cycles What you must know The difference between asexual and sexual reproduction. The role of meiosis and fertilization in sexually reproducing organisms. The importance of homologous chromosomes to meiosis. How the chromosome number is reduced from diploid to haploid through the stages of meiosis. Three important differences between mitosis and meiosis. The importance of crossing over, independent assortment, and random fertilization to increasing genetic variability. Genes: segments of DNA that code for basic units of heredity .
