Unit 3: Genetics

• How many chromosome do humans have?

  46
• Chromosomes have the same length, centromere position, and genes that control the same traits.
• What is a homologous pair of chromosomes?

  A pair of chromosomes (one from each parent) that pair together during prophase of meiosis.
• What is the difference between meiosis I and meiosis II?

  In meiosis I, the homologous pairs separate. In meiosis II, the sister chromatids separate.
• What phase of meiosis is this?

  Interphase I

  
• What phase of meiosis is this?

  Prophase I

  
• What phase of meiosis is this?

  Metaphase I

  
• What phase of meiosis is this?

  Anaphase I

  
• What phase of meiosis is this?

  Telophase I

  
• What phase of meiosis is this?

  Prophase II

  
• What phase of meiosis is this?

  Metaphase II

  
• What phase of meiosis is this?

  Anaphase II

  
• What phase of meiosis is this?

  Telophase II

  
• What "stage" does meiosis II skip?

  Interphase
• How does I go to X in interphase?

  The homologous pairs replicate themselves and develop sister chromatids.
• What happens during interphase?

  DNA replicates, chromatin condenses.
• What happens during prophase?

  Pairing of homologous chromosomes, spindles form.
• In what stage does "crossing over" occur?

  Prophase I
• What happens during metaphase?

  Homologous chromosomes line up at the equator, spindles attach to centromeres.
• What happens during anaphase?

  Homologous pairs are pulled apart.
• What happens during telophase?

  Spindles break down, two nuclei form, cell divides.
• When does cytokinesis occur?

  At the end of telophase II.
• What are three things that provide genetic variation during meiosis?

  Independent assortment

  Crossing over

  Random fertilization