 Cross TT X Tt  Give the genotypic and phenotypic ratios

 Male - spermatogenesis  Occurs frequently  Produce sperm cells  Female - Oogenesis  Occurs every 28 days  Produce one egg Do not copy

 One mother cell produces four daughter cells  Each daughter cell has haploid chromosome # (1/2 of what mother had)  Occurs in sex cells (sperm and egg)

 1. Interphase - mature cell ready for cell division  2. Prophase I - chromosomes are short, thick and double attached by centromere  3. Metaphase I - tetrads align at equator  4. Anaphase I - Tetrads split and move to opposite poles  5. Telophase I - events occur in the reverse of prophase I  Don’t copy

 6. Metaphase II - chromatids align at equator  7. Anaphase II - chromatids split and move to opposite poles  8. Telophase II - 4 cells with haploid #(new sperm and egg cells)  Don’t Copy

 Mitosis  Asexual and sexual  Identical cells produced  Same #chromosomes (46)  Body cells  One Division  Two cells made  20 minutes to one hour  Meiosis  Sexual cell division  Cells different  Different number of chromosomes (23)  Sex cells  Two divisions  4 cells made  Occurs in days

 Crossing Over  Genetic Recombination

 Trisomy - extra chromosome (down syndrome)  Monosomy - lacking a chromosome (most lethal, Turner Syndrome)  Triploidy - three sets of chromosomes  Polyploidy - more than the usual number of chromosomes (rare in animals, common in plants)

 Gene - portion of DNA that is genetically active, controls traits  Chromosome - Thread like, humans 23 pairs  Haploid chromosome # (n) - single set of chromosomes  Diploid chromosome # (2n) - two of each kind in a cell

 Homologous Chromosome - same  Allele - one-half of a gene pair (T or t)  Gamete - Sex cell, reproductive cell  Sperm - male haploid # (Father) 23 chromosomes  Egg - female haploid # (Mother) 23 chromosomes  Zygote - fertilized egg by a sperm, diploid number (2n) = 46 chromosomes, 23 pairs

Organized photo of a person’s chromosome Autosomes vs. sex chromosomes