the process of meiosis (1) by S.Vanxa

1. MEIOSIS
Reduction division.

2. THE PROCESS OF MEIOSIS
MEIOSIS AND SEXUAL REPRODUCTION.
A DIPLOID CELL HAS TWO SETS OF CHROMOSOMES, ONE FROM THE MARTENAL
SIDE AND THE OTHER FROM THE PARTENAL SIDE. A HAPLOID CELL CONSISTS OF
UNPAIRED CHROMOSOMES, NOT IN PAIRS.
SO DURING THE PROCESS OF MEIOSIS, EACH DIPLOID CELL (2n), WILL DIVIDE TO
FORM FOUR DAUGHTER CELLS WHICH ARE ALL HAPLOID (2n). THIS TYPE OF
DIVISION BY THE NUCLEUS OF A CELL, REDUCES THE CHROMOSOME NUMBER BY
HALF.

3. THE PROCESS OF MEIOSIS
• MEIOSIS IS IMPORTANT FOR SEXUAL REPRODUCTION BECAUSE IT PROMOTES
VARIATION OF THE NEW OFFSPRINGS, BY INVOLVING THE GENETIC MATERIAL OF
BOTH PARENTS.
• THIS REDUCTION DIVISION ALSO HELPS TO PREVENT MUTATIONS IN THE
OFFSPRINGS.
• MEIOSIS IS DIVIDED INTO MEIOSIS 1 AND MEIOSIS 2, MEIOSIS 1 HAS 5 DIFFERENT
STAGES AND MEIOSIS 2 HAS 4 DIFFERENT STAGES.

4. STAGES OF MEIOSIS
• STAGES OF MEIOSIS
• MEIOSIS HAS TWO SUCCESSIVE NUCLEIC DIVISIONS, WHICH ARE AS MENTIONED
ABOVE MEIOSIS 1 AND MEIOSIS 2.
• THE STAGES OF MEIOSIS ARE AS FOLLOWS, INTERPHASE, PROPHASE, METAPHASE,
ANAPHASE, AND TELOPHASE. THESE STAGES ARE THEN FOLLOWED BY
CYTOKINESIS, WHICH IS THE DIVISION OF THE CELL.
• HOMOLOGOUS CHROMOSOMES
• EVERY CELL HAS TWO SETS OF CHROMOSOMES WHICH LOOK THE SAME IN
TERMS OF STRUCTURE, LOCATION AND APPEARANCE, BUT THEY ARE NOT
IDENTICAL TO EACH OTHER.

5. HOMOLOGOUS CHROMOSOMES
• ONE CHROMOSOME IN EACH PAIR IS DERIVED FROM THE FATHER, AND THE
OTHER ONE FROM THE MOTHER.
• EACH CHROMOSOME IS FROM THE MOTHER AND THE OTHER FROM THE FATHER,
CHROMOSOMES MAY CARRY DIFFERENT OR THE SAME VERSIONS OF A GENE. E.g.
a gene for eye color either blue or brown.
• A DUPLICATED CHROMOSOME CONSTISTS OF TWO SISTER CHROMATIDS AND
ARE EMBEDDED BY A CENTROMERE IN THE CENTER.

6. STAGES OF MEIOSIS.
• MEIOSIS 1
• INTERPHASE
• HERE THE GENETIC MATERIAL WHICH IS DNA REPLICATES, TO PRODUCE MANY
COPIES OF ITSELF FOR MEIOSIS TO OCCUR.
HOWEVER THIS IS NOT A PHASE OF MEIOSIS.
• PROPHASE 1
• THE NUCLEUS AND NUCLEOLUS DISAPPEAR. SPINDLE FORMS, CHROMOSOMES
ALSO OCCUR. THUS CROSSING OVER OCCURS.
• CROSSING OVER IS A PROCESS WHEREBY THE SISTER CHROMATIDS OF
HOMOLOGOUS CHROMOSOMES TOUCH ONE ANOTHER.

7. STAGES OF MEIOSIS.
• The tetraids also forms, which is
duplicated chromosomes come in
homologous pairs.

8. STAGES OF MEIOSIS
• METAPHASE 1.
• HOMOLOGOUS CHROMOSOMES ALIGN AT THE EQUATOR
• INDEPENDENT ASSORTMENT OCCURS.
• CHROMOSOMES ALIGN RANDOMLY AT THE EQUATOR.
• AT THE CHIASMATA CROSSING OVER WILL OCCUR.
• ENHANCES GENETIC VARIATION.

10. STAGES OF MEIOSIS.
• ANAPHASE 1
• HOMOLOGOUS CHROMOSOMES SEPARATE MOVING INTO DIFFERENT POLES.
• THE SPINLDE FIBRES CONTRACTS PULLING THESE CHROMOSOMES INTO THE
DIFFERENT POLES.

12. STAGES OF MEIOSIS.
• Telophase 1
• Each pole now has a haploid set of chromosomes
• CYTOKINESIS WILL THEN OCCUR.
• THE CELL WILL SPLIT INTO TWO.
• EACH DAUGHTER CELL NOW HAS HALF THE AMOUNT OF CHROMOSOMES LIKE
THE PARENT CELL.

14. REFERENCES
Catherine.P (2012) cell division mitosis. Available from slideshare at
https://www.slideshare.net/catherinepatterson. (accessed 03 September 2018).
Mangwana.X (2014) MEIOSIS. Available from slideshare at
http://www.slideshare.net/masangwaxolani. (accessed on 03 September 2018)