Topic 2 - Cells and control

• What is the cell cycle?

  A series of events in a cell
• How is the cell cycle described?

  As the lifecycle of a cell
• What are the three stages of the cell cycle?

  • Stage 1: Interphase
  • Stage 2: Mitosis
  • Stage 3: Cytokinesis
• What is interphase?

  The longest stage of the cell cycle
• What occurs during interphase?

  Cell growth, organelle synthesis, DNA replication
• What does DNA replication involve?

  Double helix unzips, bases align, pairs join
• What is a chromosome?

  A linear DNA molecule tightly coiled around proteins
• What happens to chromosomes during DNA replication?

  The DNA in each chromatid is replicated
• What is mitosis?

  A form of cell division producing two identical cells
• Why is mitosis important in organisms?

  For asexual reproduction, growth, repair, replacement
• What are the four stages of mitosis?

  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• What occurs during prophase?

  DNA condenses, chromosomes become visible
• What occurs during metaphase?

  Chromosomes line up along the cell equator
• What occurs during anaphase?

  Spindle fibres pull chromatids to opposite poles
• What occurs during telophase?

  Nucleus divides, new membrane forms around chromosomes
• What does cytokinesis involve?

  Division of cell membrane and cytoplasm
• If a cell divides by mitosis every 2 minutes, how many cells are present after 10 minutes?

  32 cells
• What is cancer?

  Uncontrolled cell division forming tumours
• What happens to tumour cells in cancer?

  They spread to form secondary tumours
• What are percentile charts used for?

  • To monitor growth
  • Compare measurements to expected values
• What does the 95th percentile mean?

  95% of measurements are below this value
• What can doctors determine from percentile charts?

  • Slower growth (below bottom line)
  • Faster growth (above top line)
  • Abnormal growth patterns
• Describe growth in animals.

  • Cell division occurs in all body cells
  • Slower rate in adults for replacement and repair
  • Most cells differentiate early and become specialised
• Describe growth in plants.

  • Cell division occurs in meristematic tissue
  • Rate remains the same throughout life
  • Meristematic stem cells can differentiate into any cell type
  • Cell elongation occurs in all cells
• What are stem cells?

  Unspecialised cells capable of differentiation
• What is meant by ‘differentiation’?

  Process by which stem cells become specialised
• Why is cell differentiation important?

  Enables formation of specialised tissues
• What are embryonic stem cells?

  Stem cells in very early embryos
• What is the function of embryonic stem cells?

  Enable growth and development of tissues
• What are adult stem cells?

  Stem cells that differentiate into limited cell types
• What is the primary function of adult stem cells?

  Replacement of dead cells
• Where are stem cells found in plants?

  In meristems
• Where is meristem tissue found?

  In regions of continuous cell division
• What are meristematic stem cells?

  Stem cells in meristems capable of differentiation
• How can stem cells be used in medicine?

  • Collected and stimulated to differentiate
  • Transplanted into patients
  • Used to treat damage or disease
• What is the central nervous system composed of?

  Brain and spinal cord
• What is the spinal cord?

  A long structure of neurones
• What is the function of the spinal cord?

  Connects peripheral nervous system to the brain
• What are the three main regions of the brain?

  • Cerebrum
  • Cerebellum
  • Medulla oblongata
• What is structure A in the brain diagram?

  Cerebellum