1. Mitosis and Meiosis
By: Richard Shirk, Jr.

2. What Are Mitosis And Meiosis?
Both are types of reproduction used during the cell cycle
Each type of cell division are specialized for different types of cells
Both undergo the cell cycle in very similar, yet very different ways

3. Important Definitions
DNA: a molecule composed of deoxyribose nucleotides and contains the genetic information of living cells
Chromosome: a single DNA double helix together with proteins that help to organize the DNA
Chromatid: one of the two identical strands of DNA and protein that forms a replicated chromosome
Gene: a unit of heredity; specifies the amino acid sequence of proteins and hence particular traits
Allele: one of several alternative forms of a particular gene
Locus: the physical location of a gene on a chromosome

4. Important Definitions (cont.)
Diploid: referring to a cell with pairs of homologous chromosomes
Haploid: referring to a cell that has only one member of each pair of homologous chromosomes
Homologous Pair: two homologues that are similar in appearance and genetic information that pair during meiosis
Heterozygous: carrying two different alleles of a given gene
Homozygous: carrying two copies of the same allele of a given gene

5. Mitosis Mitosis is the division of chromosomes in a cell
Usually followed by cytokinesis or cell division
Daughter cells produced after mitosis have same number of chromosomes as original cell
Purpose of mitosis is replication of somatic cells and asexual reproduction
Somatic cells include all cells in the body except the egg or sperm

6. Meiosis
Meiosis is the division and reduction of the chromosomes of a cell
Daughter cells produced have half the chromosomes as the original cell
Purpose of meiosis is the production of gametes (sex cells)

7. Stages Of The Cell Cycle
Interphase
Synthesis
Prophase
Metaphase
Anaphase
Telophase

8. Interphase And Synthesis Stages Of Mitosis And Meosis
During Interphase the cell carries out normal activities such as metabolism and protein synthesis
During synthesis the DNA in each chromosome is replicated

9. Prophase And Metaphase Stages of Mitosis
The prophase stage
chromosomes condense and would be visible under a light microscope
the nuclear membrane degrades
In the metaphase stage the chromosomes line up along the equator

10. Anaphase And Telophase Stages of Mitosis And Cytokinesis
In the anaphase stage the sister chromatids separate and move to opposite ends of the cell
In the telophase stage one set of each chromosome reaches each pole
Cytokinesis begins and the cell divides in two creating two diploid cells

11. Meosis I Prophase I chromosomes visible
hHomologous pairs of chromosomes come together to from tetrads
crossing over occurs when a chromatid of one chromosome in a pair exchanges a segment of itself with the chromatid of the other chromosome in the pair

12. Meosis I (cont.) Metaphase I Anaphase I Telophase I
homologous pairs line up along the equator of the cell
Anaphase I
Homologous pairs of chromosomes separate and move to opposite poles of cell
Telophase I
Chromosomes complete their migration to poles of the cell and cytokinesis occurs

13. Meiosis II No new DNA replication takes place Prophase II
Spindle fibers re-form and chromosome begin to move to middle of cell

14. Meosis II (cont.) Metaphase II Anaphase II Telophase II
chromosomes line up along equator
Anaphase II
sister chromatids of each chromosome separate and move to poles of cells
Telophase II
the chromatids complete migration
nuclei reform and cytokinesis occurs
Meosis produces four haploid cells

15. Crossing Over Of Meosis
Increases the number of allelic combinations
Increase in different possible physical expressions and characteristics
Allows species to try varies combinations and find the best combination that suits their environment

16. Works Cited http://genetics.nbii.gov/Basic1.html