Cell Growth and Reproduction By: Carly Baurer

Cell Cycle The cell cycle is divided into two main parts: interphase and mitosis. Interphase- the cell grows and replicates its chromosomes and is subdivided into three phases: gap phase 1 (G1), synthesis (S), and gap phase 2 (G2). Interphase is followed by mitosis (nuclear division) and cytokinesis (cell division).

Diagram of The Cell Cycle

Mitosis Mitosis is the process by which a cell duplicates the chromosomes in its cell nucleus, in order to generate two, identical, daughter nuclei. Mitosis occurs exclusively in eukaryotic cells, but occurs in different ways in different species. There are many different events that occur throughout the process of mitosis:

Meiosis Meiosis occurs in eukaryotic organisms that reproduce sexually which includes plants and animals. Meiosis is a two-part cell division process that produces sex cells with one half the number of chromosomes as the parent cell. There are two stages or phases of meiosis: meiosis I and meiosis II. At the end of the meiotic process, four daughter cells are produced.

Stages of Meiosis Meiosis I -chromosomes in a diploid cell, produce two haploid daughter cells. This step generates genetic diversity. Prophase I - DNA replication takes place and homologous chromosomes pair and form synapses. Metaphase I - Homologous pairs move together along the phase plate and the homologous chromosomes align along an equatorial plane that separates the spindle. Anaphase I - Kinetochore microtubules shorten, severing the recombination nodules and pulling homologous chromosomes apart. Telophase I - each daughter cell now has half the number of chromosomes but each chromosome consists of a pair of chromatids. The chromosomes uncoil back into chromatin. Meiosis II - second part of the meiotic process, and very similar to mitosis and meiosis I. Prophase II - Centrioles move to the polar regions and arrange spindle fibers for the second meiotic division. Metaphase II -the centromeres contain two kinetochores, that attach to spindle fibers from the centrioles. Anaphase II -the centromeres are cut, and the sister chromatids get pulled apart. Telophase II -the nuclear envelopes reform and produce a total of four daughter cells. Meiosis is now complete.

Compare and Contrast Meiosis Sexual reproduction Occurs in humans, animals, plants, and fungi Crossing over occurs Creates sex cells Mitosis Cellular reproduction Occurs in all organisms Crossing over does not occur Creates anything other than sex cells They both involve the dividing of cells and the splitting of DNA between new cells formed. They are also both involved in the process of reproduction.

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