Mitosis The parent cell splits to produce two IDENTICAL daughter cells… each with the same number of chromosomes as the parent (46 chromosomes in humans) Asexual Reproduction Binary Fission EVERY cell in your body is doing it!

chromosomes duplicate parent cell chromosomes duplicate chromosome pairs line up at middle of the cell chromosome pairs are pulled apart… and go to opposite ends of the cell cell divides into two identical daughter cells

Meiosis Parent cell splits twice to produce four SEX cells … each with half the chromosomes of the parent (23 chromosomes in humans) ONLY special cells do it… they make gametes.

PART 1 PART 2 parent cell chromosomes duplicate chromosomes exchange some genetic information chromosomes line up in middle, and pull towards ends cell divides into two cells (not identical to parent) chromosomes line up in middle & pull towards the ends of each cell each cell divides… producing 4 sex cells… each with ½ chromosomes as parent cell PART 2

Sexual Reproduction Zygote Embryo female gamete: male gamete: egg with ½ chromosomes male gamete: sperm with ½ chromosomes fertilization: egg with full set of chromosomes Zygote mitosis takes over and cells reproduce Embryo Questions: What type of reproduction is shown at the top of the diagram? How many chromosomes in EGG… SPERM… ZYGOTE How many chromosomes in each of the different types of blood cells? What type of cell division will occur to replicate bone cells?.... nerve cells? How many chromosomes are present in blood cells?... in gland cells?... in a cell in your stomach? DNA tells each cell what to be and what to do

Mitosis Meiosis 1 division 2 divisions 2 offspring cells offspring cells genetically identical offspring cells have = chromosomes as parent used in ALL cells for growth, repair, asexual reproduction Meiosis 2 divisions 4 offspring cells offspring are genetically different offspring cells have 1/2 chromosomes of parent used ONLY to produce sex cells

Check your chromosome math…