Cell division

• What is the first phase of the cell cycle?

  Interphase
• What occurs during the G1 phase of interphase?

  Cell growth and normal functions
• What is the main event that occurs during the S phase of interphase?

  DNA replication
• What happens during the G2 phase of interphase?

  Preparation for mitosis and further growth
• What is the mitotic (M) phase responsible for?

  Division of the cell nucleus and its contents
• What are the two main processes that occur during the mitotic phase?

  Mitosis and cytokinesis
• What occurs during prophase of mitosis?

  Chromosomes condense, spindle fibers form, and the nuclear envelope breaks down
• What happens during metaphase of mitosis?

  Chromosomes align at the cell equator
• What is the key event in anaphase of mitosis?

  Sister chromatids separate and move to opposite poles
• What occurs during telophase of mitosis?

  Nuclear envelopes reform around each set of chromosomes, and chromosomes decondense
• What is the final step of mitosis?

  Cytokinesis
• What is the result of cytokinesis?

  Two genetically identical daughter cells
• What is the first phase of meiosis?

  Meiosis I
• What happens during prophase I of meiosis?

  Homologous chromosomes pair and exchange segments (crossing over)
• What occurs during metaphase I of meiosis?

  Homologous pairs align at the cell equator
• What is the key event in anaphase I of meiosis?

  Homologous chromosomes separate to opposite poles
• What happens during telophase I of meiosis?

  Nuclear envelopes reform, cytokinesis occurs, resulting in two haploid cells
• What is the second phase of meiosis?

  Meiosis II
• What occurs during prophase II of meiosis?

  Chromosomes condense and spindle fibers form
• What happens during metaphase II of meiosis?

  Chromosomes align at the cell equator
• What is the key event in anaphase II of meiosis?

  Sister chromatids separate to opposite poles
• What occurs during telophase II of meiosis?

  Nuclear envelopes reform, cytokinesis occurs, resulting in four genetically diverse haploid cells
• What mechanisms produce genetic variation during meiosis?

  • Crossing Over: Exchange of genetic material during prophase I
  • Independent Assortment: Random distribution of chromosomes during metaphase I
  • Random Fertilization: Combination of different gametes during fertilization
• What is an allele?

  Different forms of a gene
• What does genotype refer to?

  Genetic makeup of an organism
• What is phenotype?

  Observable traits of an organism
• What is a homozygote?

  An organism with two identical alleles for a trait
• What is a heterozygote?

  An organism with two different alleles for a trait
• What is a dominant allele?

  An allele that expresses its phenotype even in the presence of a recessive allele
• What is a recessive allele?

  An allele that only expresses its phenotype when two copies are present