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Meiosis

Meiosis. Chromosomes and Chromosome Number. Biological Characteristics such as eye color, height, or hair color is termed a trait. The Instructions for each trait are located on the chromosomes found in each cell nucleus. The DNA segment which coded for each trait are called genes. .

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Meiosis

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  1. Meiosis

  2. Chromosomes and Chromosome Number • Biological Characteristics such as eye color, height, or hair color is termed a trait. • The Instructions for each trait are located on the chromosomes found in each cell nucleus. • The DNA segment which coded for each trait are called genes.

  3. Homologous Chromosomes • Human body cells have 46 chromosomes each. • Each parent contributes 23 chromosomes resulting in 23 pairs. • The chromosomes that make up the pair are called homologous chromosomes. They are the same length and have the same centromere position.

  4. Haploid and Diploid Cells • In order to maintain the same chromosomes from generation to generation an organism produced gametes (sex cells). • Haploid cells have n chromosomes, diploid cells have 2n chromosomes. • Fertilization is the result of one haploid gamete combining with another haploid gamete.

  5. Meiosis • Meiosis is a type of cell division that reduces the number of chromosomes. • Meiosis reduces the chromosome number by half through the separation of homologous chromosomes. • http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120074/bio19.swf::Stages%20of%20Meiosis

  6. The importance of Meiosis MitosisMeiosis One Division Occurs. Two sets of division occur. DNA Replication during interphase. DNA replication occurs once before Meiosis 1. Synapsis of homologous chromosome Synapsis do occur. Do not occur. Two identical cells are formed. Four Haploid Cells are formed. Daughter Cells are identical Daughter cells are all unique. Mitosis occurs only in body cells Meiosis occurs in reproductive cells. Mitosis is involved in growth and Meiosis is involved in the repair production of gametes and providing genetic variation

  7. The importance of Meiosis • Meiosis provides genetic variation randomly. • Sexual vs. Asexual Reproduction? • Some bacterial can reproduce asexually, why would organisms evolve to reproduce sexually at the cost of finding a mate to reproduce with?

  8. The importance of Reproduction • When reproduction occurs sexually, the beneficial genes multiply faster than they do when reproduction is asexual.

  9. Questions to Answer • What is the difference between identical twins, and non identical twins? • What is the term for the sequence of DNA that code for a specific trait? • How many divisions occur in Meiosis?

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