SC.912.L.16.17 Mitosis and Meiosis
Tutorial:
Mitosis vs Meiosis by the Amoeba sisters
You need to know:
The differences and similarities in the processes of mitosis and meiosis and relate these to the processes of sexual and asexual reproduction and their consequences for genetic variation
How mitosis and meiosis lead to genetic variation.
The relationship between mutation, cell cycle, and uncontrolled cell growth potentially resulting in cancer.
The cell cycle, including the process of mitosis and be able to explain the role of mitosis in the formation of new cells and its importance in maintaining chromosome number during asexual reproduction.
The process of meiosis, including independent assortment and crossing over.
Explain how reduction division results in the formation of gametes.
Similarities between mitosis and meiosis
Both are forms of cell division.
Both begin with diploid cells.
Both occur within the nucleus of the cell.
Both go through the same steps known as Prophase, Metaphase, Anaphase, and Telophase.
Both have in common cytokinesis (The cytoplasm divides)
Cell Cycle: Continuous process in which cells grow, make copies of their chromosomes (DNA replication), and divide to form daughter cells
INTERPHASE: The cell spends most of its life in interphase, growing (G1), replicating its DNA(S Phase), and preparing to divide (G2).
MITOSIS: The nucleus divides into two nuclei
Prophase: Chromosomes condense and become visible, the nuclear envelope disintegrates, centrioles move to opposite poles and spindle fibers begin to form
Metaphase: Chromosome line up in the center of the cell Anaphase Chromosomes separate (sister chromatids)
Telophase: Chromosomes unwind, the nuclear envelope reforms and spindle fibers disappear
CYTOKINESIS: The cytoplasm divides
Cancer: Uncontrolled Cell Growth
Most Important Phases of Meiosis
Prophase I: Homologous chromosomes pair up and Crossing over may occur
Metaphase I Homologous Chromosomes line up in the center of the cell in a random fashion
Anaphase I Homologous separate
Anaphase II Sister chromatids separate
Crossing Over
During meiosis I, prophase I, the replicated homologous pair of chromosomes comes together in the process called synapsis, and sections of the chromosomes are exchanged. You can see that after crossing over, the
resultant chromosomes are neither entirely maternal nor entirely paternal but contain genes from both parents. Synapsis and crossing over occur only in meiosis. Crossing over increases genetic variations.
Independent Assortment
Independent assortment and crossing over increase genetic variation.
Comparing Methods of Reproduction
