Topic 2: cells and control

• What does the nucleus contain?

  Your genetic information
• What are chromosomes made of?

  Coils of DNA
• What is a gene?

  A section of DNA coding for a protein
• How many pairs of chromosomes are in human cells?

  23 pairs
• How many chromosomes are in human body cells?

  46 chromosomes
• What is the chromosome count in gametes?

  23 chromosomes
• What is the diploid number of chromosomes in humans?

  46 chromosomes
• What is the haploid number of chromosomes in humans?

  23 chromosomes
• What is the cell cycle and its purpose?

  • Produces new cells for growth and repair
  • Involves cell division through mitosis
• What is the stage of the cell cycle when the cell divides?

  Mitosis
• Why do multicellular organisms use mitosis?

  To grow or replace damaged cells
• What is asexual reproduction in organisms?

  Reproduction using mitosis
• What do strawberry plants use to reproduce?

  Runners formed by mitosis
• What are the main stages of the cell cycle?

  1. Interphase
  2. Mitosis
  3. Cytokinesis
• What happens to DNA during interphase?

  It spreads out in long strings
• What must a cell do before it divides?

  Grow and duplicate its DNA
• What shape do chromosomes take before cell division?

  X-shaped chromosomes
• What are the four stages of mitosis?

  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
• What occurs during prophase?

  Chromosomes condense and the nuclear membrane breaks down
• What happens during metaphase?

  Chromosomes line up at the center of the cell
• What occurs during anaphase?

  Spindle fibers pull chromosomes apart
• What happens during telophase?

  Membranes form around sets of chromosomes
• What is cytokinesis?

  Division of cytoplasm and cell membrane
• What do daughter cells contain after mitosis?

  Identical sets of chromosomes
• How can you calculate the number of cells after mitosis?

  Using the formula: number of cells = $2^n$
• If you start with 1 cell and divide it 5 times, how many cells will there be?

  32 cells
• How does growth occur in animals?

  • Through cell division and differentiation
  • Cells become specialized for functions
• What happens to most specialized cells in animals?

  They lose the ability to differentiate
• What replaces red blood cells that cannot divide?

  Adult stem cells
• How does growth occur in plants?

  • Through cell division and differentiation
  • Unique process called elongation
• What is elongation in plants?

  Growth by absorbing water into vacuoles
• What controls elongation in plant cells?

  Auxins
• What ability do many plant cells retain throughout life?

  The ability to differentiate
• What is a tumour?

  A group of cells from uncontrolled division
• What is cancer caused by?

  Uncontrolled cell division
• What are stem cells?

  • Undifferentiated cells
  • Can divide to produce similar cells
  • Some differentiate into specific functions
• What forms embryonic stem cells?

  Fusion of egg and sperm cells
• What can embryonic stem cells differentiate into?

  Any type of cell in the body
• How can scientists use embryonic stem cells?

  To replace damaged cells in diseases
• Where are adult stem cells found?

  In bone marrow