Asexual vs. Sexual Reproduction
Aseuxal Reproduction: New individuals are created when a parent makes an exact copy of itself. Examples of this is in Mitosis, Binary Fission, Budding, etc.
Somatic Cells: Body cells → Chromosome # in humans (2n) = 46
- Somatic cells are diploid in number meaning they have a full set of chromosomes. Abbreviated as 2N.
Gametes/Germ Cells: Sex cells → Chromosome # in humans (n) = 23
- Gametes are haploid in number meaning they only have half a set of chromosomes.
- Sperm (n) → Chromosome # = 23
- Ova = egg (n) → Chromosome # = 23
- Abbreviated as N
Homologous chromosomes: This is a pair of chromosomes in which each parent donates 1 chromosome to the pair.
- You could call Meiosis the "reduction division".
Spermatogenisis: The creation of four sperm cells through the process of Meiosis.
Oogenesis: Creation of an ova (egg) and three polar bodies through Meiosis.
- Tetrads and Crossing Over
- When each pair of chromosome pairs with its homologous chromosome they form a structure called a tetrad.
- Crossing Over - When tetrads are formed, homologous chromosomes may exchange portions of their chromatids (DNA).
Stages of Meiosis
|Telophase I & Cytokenisis||
|Telophase II & Cytokinesis||
- Overall Diagram
When male and female sex cells, or gametes, (n=23) combine to create a diploid zygote (2n=46).
|Parent cell goes through how many divisions?||1||2|
|# of Daughter cells produced?||2||4|
|Type of Cells produced?||Body cells||Sex cells|
|Diploid (2N) or Haploid (N) cells?||Diploid (2N)||Haploid (N)|
|# of chromosomes in Humans||46||23|
|Daughter cells indentical or different from parent cell?||Identical||Different|
|Synonyms||Synonyms for body cells: Somatic Cells||Synonyms for sex cell: Gamete, Sperm, Egg|
- Why is mitosis necessary?
- To replace dead, worn out or damaged cells.
- So that an organism can grow and develop.
- Why is meiosis necessary?
- To create gametes (sex cells) necessary for fertilization.
- Increase genetic diversity in a population.