Cell Biology - topic 1

• What does the nucleus do in a cell?

  Controls cell activities and contains DNA
• What is the role of the cytoplasm in a cell?

  Site where chemical reactions take place
• What is the function of the cell membrane?

  Controls what goes in and out of the cell
• Why are ribosomes important in cells?

  Site of protein synthesis (they make proteins from amino acids)
• What do mitochondria do in a cell?

  Release energy by respiration
• What is the difference between eukaryotes and prokaryotes?

  Eukaryotes have a nucleus; prokaryotes do not
• What is the size of an average animal cell?

  Approximately 10 micrometers
• What is the size of an average plant cell?

  Approximately 50 micrometers
• What is the size of an average prokaryotic cell?

  Approximately 5 micrometers
• What is cell differentiation?

  • Process where undifferentiated cells become specialized
  • Examples in animals: nerve, muscle, sperm cells
  • Examples in plants: xylem, phloem, root hair cells
• What is the role of the axon in a nerve cell?

  Carries impulses around the body
• What does the acrosome in a sperm cell contain?

  Enzymes for penetrating the egg cell membrane
• What is the function of muscle cell fibers?

  They shorten for muscle contraction
• What is the function of xylem cells?

  Transport water and minerals in plants
• What is the role of phloem cells?

  Transport sugars and nutrients in plants
• What is the purpose of root hair cells?

  Maximize absorption of water and minerals
• What are the differences between light and electron microscopes?

  • Light microscopes: low magnification, low resolution, easy to operate, cheap
  • Electron microscopes: high magnification, high resolution, need training, expensive
  • Electron microscopes reveal more subcellular structures
• How do you convert millimeters to micrometers?

  Multiply by 1000
• What is the formula for magnification?

  Magnification = size of image / real size
• If a root hair cell image is 5 mm and real size is 20 micrometers, what is the magnification?

  250 times
• If a sperm cell image is 10 mm and magnification is 2000, what is the real length?

  5 micrometers
• What is binary fission in bacteria?

  • Simple cell division method
  • Bacteria can double every 20 minutes
  • Requires suitable temperature and nutrients
• How many bacterial cells are present after 4 hours if starting with 200 cells?

  Over 68 million cells
• What are the steps to grow uncontaminated cultures of microorganisms?

  1. Sterilize workspace and materials
  2. Use an inoculating loop to transfer bacteria
  3. Seal petri dish to prevent contamination
  4. Incubate at 25 degrees Celsius
• How do antibiotics affect bacteria in a petri dish?

  They create areas of dead bacteria
• How do you calculate the area of dead bacteria in a petri dish?

  Use $\pi r^2$ formula
• What are the stages of the cell cycle?

  1. Stage 1: Cell growth and structure increase
  2. Stage 2: Mitosis (chromosomes line up and divide)
  3. Stage 3: Cytoplasm and membranes divide
• What is the result of mitosis?

  Two genetically identical daughter cells
• What are stem cells?


  • Undifferentiated cells
  • Can develop into specialized cells
  • Found in embryos and some adult tissues
• What happens to the cell during stage two of the cell cycle?

  The cell grows and increases subcellular structures
• What is formed when DNA replicates?

  Two copies of each chromosome
• What is the key event in stage three of the cell cycle?

  The nucleus divides and cytoplasm divides
• What do we call the process that results in two genetically identical cells?

  Mitosis
• What are the four key points to remember about mitosis?

  Chromosomes line up, pulled apart, nucleus divides
• What are embryonic stem cells and their potential uses?

  • Undifferentiated cells from fertilized egg
  • Can differentiate into most cell types
  • Used in medical treatments (e.g., paralysis, diabetes)
• Where are adult stem cells commonly found?

  In bone marrow
• What can stem cells from bone marrow differentiate into?

  Mainly blood cells
• What are the uses of plant stem cells found in meristem tissue?

  • Differentiate into any plant cell type
  • Clone rare species to prevent extinction
  • Produce large numbers of plants with special features
• What is therapeutic cloning?

  Cloning using a patient's body cell nucleus
• What is a major advantage of therapeutic cloning?

  Tissues are not rejected by the patient