Meiosis + mitosis

• How do prokaryotic cells replicate?

  By binary fission
• How do viruses replicate?

  Inside host cells by injecting nucleic acid
• What are the stages of the cell cycle?

  • Interphase (G1, S, G2)
  • Nuclear division (mitosis or meiosis)
  • Cytokinesis
• What percentage of the cell cycle is interphase?

  About 90% or longer
• What happens during the G1 phase?

  Organelles double and cell grows
• What occurs during the S phase?

  DNA replication happens
• What is the purpose of the G2 phase?

  Final growth and error checking
• What happens if a mutation is detected in G2?

  The cell is destroyed
• What are the four key stages of mitosis?

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
• How many rounds of division occur in mitosis?

  One round of division
• What type of cells are produced by mitosis?

  Genetically identical diploid cells
• What does the acronym PMAT stand for in mitosis?

  Prophase, Metaphase, Anaphase, Telophase
• What happens to chromosomes during prophase?

  They condense and become visible
• What occurs to the nuclear envelope during prophase?

  It starts to disintegrate
• What is the role of spindle fibers in metaphase?

  They attach to chromatids at centromeres
• What happens during anaphase?

  Chromatids are pulled to opposite poles
• What energy molecule is required during anaphase?

  ATP
• What happens to chromosomes during telophase?

  They become longer and thinner
• What is cytokinesis?

  Splitting of the cytoplasm
• What is the mitotic index?

  Ratio of cells in mitosis to total cells
• How do you calculate the mitotic index?

  Divide cells in mitosis by total cells
• What might an exam question specify regarding cells in mitosis?

  To look at only complete cells
• What indicates that a cell is going through mitosis?

  Visible chromosomes
• What are the key behaviors of chromosomes during mitosis?

  • Condensation in prophase
  • Alignment in metaphase
  • Separation in anaphase
  • Decondensation in telophase
• How does meiosis differ from mitosis?

  Meiosis creates haploid cells, mitosis creates diploid cells
• What type of cells does meiosis produce?

  Haploid gametes
• What is the purpose of meiosis?

  To create gametes with half genetic information
• How many stages are there in meiosis?

  Two stages: meiosis I and meiosis II
• How many pairs of chromosomes do humans have?

  23 pairs
• What happens to chromosomes during meiosis?

  They copy and then split twice
• What is the result of meiosis I?

  Two haploid cells
• What is the result of meiosis II?

  Four genetically different gametes
• How does meiosis contribute to genetic variation?

  By producing genetically different gametes
• What is prophase I in meiosis?

  First stage where chromosomes condense
• What happens to the nuclear envelope during prophase I?

  It breaks down
• What forms from the centrioles during prophase I?

  Spindle fibers
• What is crossing over in meiosis?

  Exchange of DNA between homologous chromosomes
• Why is crossing over important for genetic variation?

  It shuffles alleles between chromosomes
• What do homologous chromosomes do during crossing over?

  They line up and twist around each other
• What is the significance of genetic variation in offspring?

  It increases chances of genetic advantages