Chromosomes and Mitosis

Eukaryotic Chromosomes Made of DNA and protein When a cell is not dividing, chromosomes are long, thin strands of chromatin

Function is to pass on traits Structure of chromosome: Sister chromatids – copied DNA Centromere – attaches each pair of chromatids

Each organism has a characteristic # of chromosomes Ex. Humans have 46 chromosomes Sexually reproducing organisms have 2 sets of homologous chromosomes w/ same genetic info

Mitosis Division of nucleus Occurs in 4 stages: PMAT Prophase Metaphase Anaphase Telophase http://www.stolaf.edu/people/giannini/flashanimat/celldivision/crome3.swf

Phase 1: Prophase Chromosomes become visible Centrioles move to either side of cell Spindle fibers form Chromosomes attach to spindle at centromeres Nuclear membrane and nucleolus disappear KEY WORD: PAIR

Phase 2: Metaphase Phase 3: Anaphase Chromosomes line up along the middle of the cell KEY WORD: MIDDLE Phase 3: Anaphase Sister chromatids separate into individual chromosomes Chromosomes move to either end of the cell KEY WORDS: APART & AWAY

Mitosis is followed by cytokinesis Phase 4: Telophase Chromosomes uncoil Nuclear membrane forms around each set of chromosomes Nucleolus reappears KEY WORD: TWO NUCLEI Mitosis is followed by cytokinesis Cleavage furrow in animal cells Cell plate in plant cells

Summary: Results in 2 daughter cells which are identical to the parent cell Form of asexual reproduction Used for growth and repair of tissue Unicellular organisms use it to reproduce

http://www.loci.wisc.edu/outreach/bioclips/CDBio.html