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Presentation on theme: "Meiosis."— Presentation transcript:

1 Meiosis

2 Haploid (n)-- one set of chromosomes
Diploid (2n)-- two sets of chromosomes Most plant and animal and adult cells are diploid (2n) Eggs and sperm are haploid (n) Meiosis is a process to convert a diploid cell to a haploid gamete, and cause a change in the genetic information to increase diversity in the offspring.


4 Interphase During this stage, each individual chromosome replicates,


6 Prophase 1 Each chromosome then actively seeks out its homologous chromosome, as shown in the graphical representation. After the homologous chromosomes pair, the structure is referred to as a tetrad (four chromatids)



9 Metaphase 1 At metaphase, each chromosome has reached its maximum density. The homologous pairs allign at the center of the cell. Small fibers attach to the centromere.


11 Metaphase I Metaphase I

12 Anaphase 1 Anaphase I pulls apart the tetrad, separating each homologous chromosome.

13 Anaphase 1


15 Telophase 1 two nuclear envelopes begin to surround the separate chromosomes and two separate cells form

16 Telophase


18 Prophase2 During Prophase II, each dyad (1/2 a tetrad) is composed of a pair of sister chromatids and they are connected by a centromere Begins to move toward center of cell

19 Prophase2


21 Metaphase2 Metaphase II is similar to Metaphase I in that the dyads are lined up at a metaphase plate by the spindle fibers.

22 metaphase2


24 Anaphase 2 Anaphase II separates the dyads into individual chromatids. Each sister chromatid ends up on one side of the cell.

25 Anaphase 2


27 Telophase2 At the end of Telophase II, the nuclear envelopes forms around each set of DNA and the cytoplasm divides once again. As a result, four haploid cells have formed from one diploid cell. The chromosomal content of a haploid cell in one-half the chromosomal content of a diploid cell ( n as opposed to 2n )



30 Two Laws Mendel's Law of Segregation states that the 2 alleles of each gene pair separate into different gametes (egg or sperm) as these are formed prior to reproduction.


32 The law of independent assortment: during gamete formation the segregation of the alleles of one allelic pair is independent of the segregation of the alleles of another allelic pair


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