1. Sources of Genetic Variation
Mitosis vs. meiosis
Sources of Genetic Variation

2. Mitosis vs. meiosis

3. mitosis ASEXUAL REPRODUCTION Makes BODY CELLS Makes 2 CELLS
Daughter Cells Are GENETICALLY IDENTICAL to the parent - CLONES
Makes DIPLOID Cells
Advantage – FAST
Disadvantage – LACK OF GENETIC VARIATION!!

4. meiosis SEXUAL REPRODUCTION Makes SEX CELLS Makes 4 CELLS
Daughter Cells are GENETICALLY DIFFERENT from the parent
Makes HAPLOID Cells
Advantage – GENETIC VARIATION!!
Disadvantage – LONG TIME

5. Attaches to the Spindle Fibers
Sister Chromatids
Attaches to the Spindle Fibers

6. SOURCES OF GENETIC VARIATION
MEIOSIS – we just talked about this
Crossing Over – when parts of chromosomes TOUCH and CHANGE genetic material during Prophase 1 in meiosis
This is how mothers produce different eggs and how fathers produce different sperm

7. SOURCES OF GENETIC VARIATION
Genetic Recombination – 2 different cells (sperm & egg) must join together in order to make a new individual
Meiosis
Mitosis

8. Non-Disjunction
When chromosomes fail to SEPARATE PROPERLY during meiosis
Produces sperm and eggs that have an ABNORMAL number of chromosomes
They should always have 23
This commonly leads to DOWN SYNDROME – when a child is born with 3 copies of chromosome 21
Called a trisomy-21

9. Downs syndrome