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INTRODUCTION TO MEIOSIS

INTRODUCTION TO MEIOSIS. Mendel’s Principles require: Each organism must inherit a single copy of every gene from each parent 2) When an organism makes gametes, the two alleles must be separated so that each gamete gets just one allele. So . . . .

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INTRODUCTION TO MEIOSIS

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  1. INTRODUCTION TO MEIOSIS

  2. Mendel’s Principles require: • Each organism must inherit a single copy of every gene from each parent • 2) When an organism makes gametes, the two alleles must be separated so that each gamete gets just one allele

  3. So . . . . When gametes are formed, there must be a process that separates the two alleles so that each gamete ends up with just one set.

  4. Scientists later found out that the genes studied by Mendel are located on chromosomes in the cell nucleus

  5. Chromosomes

  6. -Most organisms have 2 sets of chromosomes, 1 set from each of their parents -These 2 sets are called homologous chromosomes, meaning that each chromosome from the male parent has a corresponding chromosome from the female parent.

  7. Humans have 46 chromosomes. 23 chromosomes from DAD 23 chromosomes from MOM YOU Have 46 chromosomes

  8. 23 pairs of chromosomes

  9. -A cell with both sets of homologous chromosomes is diploid represented as 2N -Diploid cells have 2 complete sets of chromosomes and, therefore, 2 complete sets of genes (AGREES WITH MENDEL’S PRINCIPLES!) -Gametes (produced during sexual reproduction) have only 1 set of chromosomes and, therefore, only 1 set of genes These cells are called haploid represented as N

  10. HUMAN CELLS Haploid gametes Diploid adult 23 (N) 46 (2N) 23 (N)

  11. So . . . How are haploid (N) gametes produced from diploid (2N) cells?

  12. MEIOSIS!!!!

  13. Meiosis a process of reduction division in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell. Made up of: -Meiosis I: Prophase I, Metaphase I, Anaphase I, Telophase I -Meiosis II: Prophase II, Metaphase II, Anaphase II, Telophase II Similar to mitosis in some ways, but very different in others!

  14. Mitosis: -makes 2 daughter cells -daughter cells are diploid (2N) -asexual reproduction -genetically same Result in humans: cells with 46 chromosomes Meiosis: -makes 4 gametes -gametes are haploid (N) -sexual reproduction -genetically different Result in humans: cells with 23 chromosomes

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