Week 7

Unit: Mitosis & Meiosis Textbook Mitosis: CH10-1 & 10-2 pg Meiosis: CH 11-4 pg Binary Fission: CH 19-1 pg Key Concepts The larger a cell becomes, the more demands the cell places on its DNA. In addition, the cell has more trouble moving enough nutrients and wastes across the cell membrane. Mitosis is a type of cell division that produces two genetically identical diploid daughter cells. Mitosis produces new cells for growth and repair. Mitosis produces all the cells in our body except sperm and eggs. To ensure that each daughter cell receives a complete copy of the DNA in the parent cell, the DNA in each chromosome is replicated, and then the two copies of each chromosome are separated into two genetically identical daughter cells. Biologists divide the events of mitosis into four phases: prophase, metaphase, anaphase, and telophase. Mitosis insures that each daughter cell has the same genetic information as the parent cell. A different type of cell division, called meiosis, produces haploid gametes (sperm and eggs). After the DNA is replicated, the first meiotic cell division separates each pair of homologous chromosomes and the second meiotic cell division separates the sister chromatids of each chromosome. This process produces genetically diverse haploid gametes. A haploid sperm fertilizes a haploid egg to produce a diploid zygote which has received half of its genes from the father and half from the mother. The zygote undergoes repeated mitosis to produce an embryo and ultimately a baby. As a result of meiosis and fertilization, each offspring has half of his/her genes from his/her mother and half from his/her father. As a result, children tend to resemble their parents and their siblings. However, the genetic diversity of the sperm and eggs results in genetic diversity of the different offspring produced by the same mother and father. Bacteria divide through a process known as binary fission. Binary fission does not involve the exchange or recombination of genetic information, it is an asexual form of reproduction. Key Vocabulary Mitosis, meiosis, binary fission, cell cycle, interphase, prophase, metaphase, anaphase, telophase, cytokinesis, chromosome, chromatin, chromatid, centromere, haploid, diploid, homologous chromosome, surface area to volume Key Questions Resources The online edition of the biology (dragonfly) book or the textbook itself Lesson Ideas