mitosis and meiosis

• What is the primary function of the cell cycle?

  To duplicate DNA and segregate it into genetically identical daughter cells
• How many phases does the eukaryotic cell cycle usually occur in?

  Four phases
• What are the three phases of interphase?

  G1, S, and G2 phases
• What occurs during M phase of the cell cycle?

  The nucleus divides in mitosis, followed by cytoplasm division in cytokinesis
• What are the phases of the cell cycle?

  • Interphase
  • G1 Phase: Growth phase
  • S Phase: DNA synthesis/replication
  • G2 Phase: Preparation for mitosis
  • M Phase: Mitosis and cytokinesis
• What happens during the G1 phase of the cell cycle?

  The cell grows and increases metabolic activity
• What options does a cell have during the G1 phase?

  Continue to S phase, enter G0 phase, or become arrested in G1 phase
• When does S phase start?

  When DNA synthesis/replication commences
• What is the role of base pairing in DNA replication?

  It allows each strand to act as a template for producing a complementary strand
• What does semi-conservative DNA replication produce?

  Two complete DNA double helices from the original molecule
• What is the function of helicase and topoisomerase during DNA replication?

  They unwind the double helix
• What does DNA polymerase do during DNA replication?

  It produces the leading strand copy and binds to the lagging strand
• What are Okazaki fragments?

  Discontinuous segments made on the lagging strand during DNA replication
• What is the role of DNA ligase in DNA replication?

  It joins Okazaki fragments together
• What occurs during the G2 phase of the cell cycle?

  Protein synthesis and rapid cell growth to prepare for mitosis
• What is checked at the G2 checkpoint?

  For any DNA damage within the chromosomes
• What does M phase consist of?

  Nuclear division (karyokinesis) and cytokinesis
• What is the purpose of mitosis?

  To separate replicated chromosomes into two new nuclei
• What does mitosis give rise to?

  Genetically identical cells
• What are the key terms related to mitosis?

  • Centrosome: Main microtubule organizing center
  • Microtubules: Polymers of tubulin forming part of the cytoskeleton
  • Chromatid: One half of a duplicated chromosome
  • Sister Chromatids: Identical copies of a chromosome
  • Kinetochore: Protein structure where spindle fibers attach
• What happens during prophase of mitosis?

  The cell condenses its chromosomes and initiates mitotic spindle formation
• What occurs during prometaphase of mitosis?

  The nuclear envelope disintegrates and microtubules invade the nuclear space
• What is the role of the metaphase checkpoint?

  To ensure kinetochores are properly attached to the mitotic spindle
• What happens during anaphase of mitosis?

  Cohesins are cleaved, pulling sister chromatids apart
• What occurs during telophase of mitosis?

  Reversal of prophase events and formation of a new nuclear envelope
• What is cytokinesis?

  A separate process necessary for completing cell division
• What forms during cytokinesis?

  A cleavage furrow containing a contractile ring
• What is the outcome of cytokinesis?

  Each daughter cell has a complete copy of the genome of its parent cell
• What is meiosis?

  A special type of cell division that produces gametes
• How many rounds of division occur in meiosis?

  Two rounds of division
• What is the result of meiosis?

  Four cells with only one copy of each chromosome (haploid)
• What happens to genetic material before meiosis?

  It is crossed over, creating new combinations of code
• What happens during fertilization after meiosis?

  The haploid cells fuse to create a zygote with two copies of each chromosome
• How does meiosis differ from mitosis?

  Meiosis involves two rounds of division and produces haploid cells
• What are the phases of meiosis?

  • Meiosis I
  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I
  • Meiosis II
  • Prophase II
  • Metaphase II
  • Anaphase II
  • Telophase II
• What occurs during prophase I of meiosis?

  Homologous chromosomes pair and exchange genetic information
• What happens during metaphase I of meiosis?

  Homologous pairs move together along the metaphase plate
• What occurs during anaphase I of meiosis?

  Kinetochore microtubules shorten, pulling homologous chromosomes to opposite poles
• What happens during telophase I and cytokinesis of meiosis?

  Two daughter cells are formed, each with half the number of chromosomes
• What occurs during prophase II of meiosis?

  Nucleoli and nuclear envelope disappear, and chromatids shorten and thicken