meiosis

• At the end of meiosis, the result is 4 cells, whereas mitosis results in 2 cells
• Meiosis - the process for creating sperm and egg cells
• Sperm and Egg cells are also known as gametes
• The two goals of meiosis are to make cells with half the chromosomes, and to mix up the genes
• Haploid - cells with half the chromosomes
• chromatids are copied to form sister chromatids in Interphase I
• 2 stages of meiosis:

  Meiosis I -> homologous pairs are separated

  Meiosis II -> Sister chromatids are separated
• Meiosis's result is 4 haploid cells
• homologous chromosomes - a pair of chromosomes containing the same sets of genes
• Humans have 23 pairs of homologous chromosomes
• meiosis is more efficient in males then in females
• crossing over - process by which non-sister chromatids from homologous chromosomes exchange genes
• diploid (2n) - two copies of each chromosome
• All body cells are diploid
• Haploid (n) - one copy of each chromosome
• Sperm and Egg are haploid
• nondisjunction - meiotic spindle works incorrectly -> chromosomes fail to seperate
• Nondisjunction can happen during meiosis I or meiosis II
• DNA only replicated once in meiosis and mitosis
• zygote - the fertilized egg that develops into a new organism
• a group of tissue is called an organ
• allele - one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome