CELL DIVISION (CELLS)

• What are the main stages of the cell cycle?

  The main stages of the cell cycle are interphase (G1, S, G2) and the mitotic phase (mitosis and cytokinesis).
• Define mitosis.


  Mitosis is the process of nuclear division in eukaryotic cells that results in two genetically identical daughter cells from a single parent cell.
• Define meiosis.


  Meiosis is the process of nuclear division that reduces the chromosome number by half, resulting in four genetically diverse gametes
• What is the purpose of mitosis in multicellular organisms?

  The purpose of mitosis is growth, repair, and asexual reproduction
• What is the purpose of meiosis in multicellular organisms?

  To produce gametes for sexual reproduction, ensuring genetic diversity
• What is cytokinesis?

  Cytokinesis is the division of the cytoplasm to form two separate daughter cells after mitosis or meiosis
• What are chromosomes made of?

  Chromosomes are made of DNA and proteins, specifically histones.
• Define chromatid.


  A chromatid is one-half of a duplicated chromosome, joined to its sister chromatid at the centromere
• What is a centromere?

  A centromere is the region of a chromosome where the two sister chromatids are joined together and where the spindle fibres attach during cell division
• Describe the events of interphase.

  Interphase consists of three stages: G1 (cell growth), S (DNA replication), and G2 (preparation for mitosis)
• What happens during the G1 phase of interphase?

  During the G1 phase, the cell grows and synthesizes proteins necessary for DNA replication
• What happens during the S phase of interphase?

  During the S phase, DNA is replicated, resulting in two identical sets of chromosomes
• What happens during the G2 phase of interphase?

  During the G2 phase, the cell continues to grow, produce proteins, and prepare for mitosis
• How does the cell ensure DNA is replicated correctly?

  The cell has DNA repair mechanisms and checkpoints, particularly the G2 checkpoint, to ensure DNA is replicated correctly
• What is the significance of the G0 phase?

  The G0 phase is a resting state where cells are not actively dividing. Cells can enter G0 temporarily or permanently, depending on their type and function
• What are cell cycle checkpoints?

  Cell cycle checkpoints are control mechanisms that ensure the accuracy of cell division, including the G1, G2, and M checkpoints
• What is apoptosis?


  Programmed cell death / cell suicide
• List the stages of mitosis in order.

  The stages of mitosis are prophase, metaphase, anaphase, and telophase
• Describe what happens during prophase.

  During prophase, chromosomes condense, the nuclear envelope breaks down, and spindle fibres begin to form
• Describe what happens during metaphase.

  During metaphase, chromosomes align along the metaphase plate in the centre of the cell
• Describe what happens during anaphase.

  During anaphase, sister chromatids are pulled apart by spindle fibres towards opposite poles of the cell.
• Describe what happens during telophase.

  During telophase, chromosomes reach the poles, nuclear envelopes reform around each set of chromosomes, and the chromosomes begin to decondense
• What is the role of the spindle fibres in mitosis?

  Spindle fibers attach to chromosomes at the centromere and help separate the sister chromatids during mitosis.
• How do centrioles function in cell division?

  Centrioles help organize the formation of the spindle fibres in animal cells during cell division
• How is the nuclear envelope involved in mitosis?

  The nuclear envelope breaks down during prophase and re-forms during telophase to separate the newly divided nuclei
• What changes occur to the nucleolus during mitosis?

  The nucleolus disappears during prophase and reappears during telophase as the nucleus re-forms
• How does meiosis differ from mitosis?

  Meiosis involves two rounds of cell division resulting in four genetically diverse haploid cells, while mitosis involves one division resulting in two genetically identical diploid cells.
• How do mutations contribute to genetic variation?

  Mutations introduce new genetic variations by altering DNA sequences
• What are gametes?


  Gametes are haploid sex cells (sperm and eggs) produced by meiosis.
• How are gametes formed?

  Gametes are formed through the process of meiosis in the reproductive organs.
• What is cancer?


  Cancer is a disease characterized by uncontrolled cell division due to mutations in genes regulating the cell cycle.
• How do environmental factors contribute to cancer?

  Environmental factors such as radiation, chemicals, and viruses can cause mutations leading to cancer.
• What is the purpose of a root tip squash in studying mitosis?


  A root tip squash allows observation of actively dividing cells, making it easier to study the stages of mitosis.
• Describe how you would prepare a slide to observe mitosis?

  To prepare a slide, you would fix the root tip, stain it to highlight chromosomes, and then squash it to spread the cells for microscopic observation.
• How can you identify the different stages of mitosis under a microscope?

  You can identify stages based on the appearance of chromosomes: condensed and visible in prophase, aligned at the centre in metaphase, separating in anaphase, and forming two nuclei in telophase.
• Describe the role of the mitotic spindle in chromosome segregation.

  The mitotic spindle organizes and separates chromosomes by attaching to their centromeres and pulling sister chromatids to opposite poles.
• What are centrosomes and what is their function during cell division?

  Centrosomes are the main microtubule-organizing centres in animal cells, crucial for forming the mitotic spindle and ensuring proper chromosome segregation.
• Summarize the key differences between mitosis and meiosis.

  Mitosis produces two identical diploid cells, involves one division, and maintains chromosome number. Meiosis produces four genetically diverse haploid cells, involves two divisions, and reduces chromosome number by half.
• What are the 2 methods of cell division?

  Mitosis and meiosis
• What is created through mitosis?

  2 genetically identical daughter cells. they have the same number of chromosomes as the parent cell.