The Importance of Mitosis The need to heal! The need to grow! DNA Made of nucleotides Phosphate sugar Nitrogen base Adenine Guanine Cytosine thymine Coiling Uncoiled DNA called chromatin- between cell divisions Happens during cell division DNA wraps tightly around proteins called histones Chromosomes Chromosome- consists of two identical halves connected together by a cnetromere Chromatid- a half of one chromosome. Contains one complete set of information Copies itself to make the other chromatid How many chromosomes?? Each human diploid cell is 2N and contains 46 total 23 identical pairs ( 23 x 2 = 46 ) “homologous chromosomes” carry the same traits How many chromosomes?? Egg and sperm cells only carry one set of 23 Each human haploid cell is “N” Egg and sperm combine to form 2N or 46 All other chromosomes are called autosomes Each human or animal cell has sex chromosomes XX or XY Define the sex of the organism Cell Cycle G1 = cell grows S = DNA replication G2= Prepare to divide M= Mitosis INTERPHASE Stages of Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Interphase What Stage? What Stage? What Stage?