Cell cycle and Cell division

• What is the cell cycle?

  The cell cycle is the life cycle of a cell.
• What are the three parts that make up interphase in the cell cycle?

  • Growth 1 (G1)
  • Synthesis (S)
  • Growth 2 (G2)
• What percentage of the entire cell cycle does interphase comprise?

  About 95%
• What is the purpose of interphase in the cell cycle?

  Interphase prepares the cell for mitosis and cytokinesis.
• What is mitosis?

  Mitosis is the splitting of the nucleus.
• What is cytokinesis?

  Cytokinesis is the splitting of the cytoplasm.
• What occurs during the G1 phase of interphase?

  • Organelle replication (e.g., mitochondria)
  • Cell growth in size
  • Protein synthesis
  • Respiration for energy (ATP)
• What happens during the synthesis (S) phase of interphase?

  DNA replication occurs during the synthesis phase.
• What is the main difference between G1 and G2 phases of interphase?

  • G1 focuses on organelle replication and cell growth.
  • G2 checks for DNA damage and replication errors.
• What is the purpose of the G1 checkpoint?

  The G1 checkpoint checks for organelle presence, cell size, and DNA errors.
• What happens if DNA damage is detected at the G1 checkpoint?

  The cell will stop progressing to the synthesis phase.
• What is the G0 phase?

  The G0 phase is a resting state where the cell is not actively dividing.
• What are the reasons a cell might enter the G0 phase?

  • Differentiation into specialized cells
  • DNA damage detected
  • Cells become senescent and cannot divide anymore
• What is the role of checkpoints in the cell cycle?

  Checkpoints ensure that the cell has the correct components and no errors before proceeding.
• What are the three main checkpoints in the cell cycle?

  1. G1 checkpoint: checks organelles, size, and DNA errors
  2. G2 checkpoint: checks for DNA replication errors
  3. Metaphase checkpoint: checks spindle fiber attachment
• What happens during the metaphase checkpoint?

  The metaphase checkpoint ensures that chromosomes are properly attached to spindle fibers.
• How does a cell become senescent?

  A cell becomes senescent after reaching its maximum number of divisions.
• What is the relationship between cell cycle checkpoints and cancer development?

  • Mutated cells may bypass checkpoints.
  • This allows for uncontrolled cell division.
  • Resulting in more cells with mutated DNA.
• What are the four phases of mitosis?

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
• What is the significance of the spindle fibers during mitosis?

  Spindle fibers guide chromosomes to opposite poles of the cell.
• What is the consequence of improper attachment of chromosomes to spindle fibers?

  It may result in an uneven distribution of DNA during cell division.
• What is the overall process of the cell cycle?

  1. Interphase (G1, S, G2)
  2. Mitosis (splitting of the nucleus)
  3. Cytokinesis (splitting of the cytoplasm)
• Cell growth involves an increase in size due to protein synthesis and DNA replication.
• The cell cycle is the process by which cells grow, divide, and reproduce.
• Interphase is the longest phase of the cell cycle where most of the cell's activities occur.
• What is meiosis?

  Meiosis is a type of cell division.
• How many types of cell division are there?

  There are two types of cell division: mitosis and meiosis.
• What is the purpose of mitosis?

  Mitosis helps us grow and repair damaged tissues.
• What is the role of meiosis in sexual reproduction?

  Meiosis produces gametes, which are haploid cells.
• What are gametes?

  Gametes are haploid cells like sperm and egg cells.
• What happens during the S-phase of interphase in meiosis?

  DNA synthesis or replication occurs, doubling the chromosomes.
• What connects the two sister chromatids together?

  The centromere connects the two sister chromatids.
• What is the difference between centromeres and centrioles?

  Centromeres connect sister chromatids, while centrioles form spindle fibers.
• What occurs during prophase one of meiosis?

  The nuclear envelope disappears, and homologous chromosomes pair up.
• What are homologous chromosomes?

  Homologous chromosomes are chromosomes that are not identical but have the same structure and genes.
• What is crossing over in meiosis?

  Crossing over is the swapping of alleles between homologous chromosomes.
• What is independent assortment in meiosis?

  Independent assortment is the random arrangement of homologous chromosomes during metaphase one.
• What happens during anaphase one of meiosis?

  The homologous chromosome pairs are pulled apart to opposite sides of the cell.
• What is the difference between anaphase one and anaphase two?

  In anaphase one, homologous chromosomes are separated, while in anaphase two, sister chromatids are separated.
• What is the result of meiosis one?

  Meiosis one results in two haploid cells.