2/10/12: Understand how mitosis relates to reproduction Was the parent cell diploid or haploid? How do you know? Were the daughter cells diploid or haploid? How do you know? At the end of mitosis, does the parent cell still exist? Explain. Suppose one of the daughter cells enters mitosis. What will the result be? What were two limitations of this representation of mitosis? How does the process of mitosis ensure that new cells are genetically identical to old cells?

Homework: Mitosis Practice More about Mitosis Homework: Mitosis Practice

Cell Division in Plant Cells Most plant species do not have centrioles During mitosis in a plant cell, the spindle fibers are organized by centrosomes instead of centrioles *The centrosome is where the centrioles are located in an animal cell The most significant difference is found during cytokinesis Plant cells have a rigid cell wall Vesicles containing cellulose collect in the middle of the cell and begin to fuse together—this is called the cell plate and it will become part of the new cell wall

Asexual Reproduction Organisms that reproduce asexually use mitotic cell divisions to reproduce This means that offspring are genetically identical to the parents There a few different mechanisms for asexual reproduction Binary fission: observed in both prokaryotes and eukaryotes, but generally associated with bacteria Budding: observed in some fungi species (primarily yeast)

Notation: n is used to represent the cell’s haploid number (for humans, n=23) 2n represents the cell’s diploid number (for humans, 2n=46) This notation is helpful for designating arbitrary cells as diploid or haploid

Notes on the Diagram “Alternation of generations” describes the life cycle of most flowering plants They alternate between diploid and haploid generations Zygote: a single cell formed by the fusing of two gametes (fertilization) Each gamete is haploid, so the zygote is diploid --phyte: plant Gametophyte (haploid): plant that produces (haploid!) gametes Spores: durable haploid cell that can germinate to form a gametophyte Sporophyte (diploid): plant that produces spores