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Meiosis. Chapter 6, section 3 Pgs. 188-191. How many chromosomes are in cells?. Different species have different numbers of chromosomes in their cells I.e. humans have 46, or 23 pairs. What are homologous chromosomes?.
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Meiosis Chapter 6, section 3 Pgs. 188-191
How many chromosomes are in cells? • Different species have different numbers of chromosomes in their cells • I.e. humans have 46, or 23 pairs
What are homologous chromosomes? • Homologous chromosomes have the same sequence of genes and the same structure • They “match” gene for gene, but their alleles might be different
What role do chromosomes play in reproduction? • Diploid cells have homologous chromosomes • Sex cells are haploid, they only have half • Male sex cells = sperm • Female sex cells = egg • When they join they create a diploid cell.
What is meiosis? • Meiosis is a process in cell division where the number of chromosomes reduces to half the starting number when the nucleus divides twice. • It makes sex cells (sperm and egg)
What are the steps of meiosis? • Chromosomes copied • Chromosomes line up • Homologous pairs separate • Cell divides • Chromosomes line up again • Chromatids pull apart • Membranes re-from around individual chromatids forming sex cells
How does meiosis explain Mendel’s results? • The creation of sex cells explains how Mendel’s plants were able to reproduce offspring with heterozygous genotypes
How is meiosis involved in inheritance? • Sex cells combine in order to produce offspring • Half of the genetic material comes from mom and half from dad