Cell Structure

• Functions of Plant cell structures:

  Chloroplast: Organelle that contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis. Contains the enzymes needed for photosynthesis.

  Cell wall: Plant and bacterial cell walls provide structure and protection. Only plant cell walls are made from cellulose.

  Permanent vacuole: Filled with cell sap to help keep the cell swollen.
• Functions of Cell structures:

  Cytoplasm: A jelly-like material that contains dissolved nutrients and salts and structures called organelles. It is where many of the chemical reactions happen.

  Nucleus: Contains genetic material, including DNA, which controls the cell's activities.

  Cell membrane: It is permeable to allow some substances but not to others and so controls the movement of substances in and out of the cell.

  Mitochondria: Organelles that contains the enzymes for respiration, and where most energy is released in respiration.

  Ribosomes: Tiny structures where protein synthesis occurs.
• Features of an animal cell:

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Ribosomes
  • Mitochondria
• Features of a plant cell:

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Cell wall
  • Vacuole
  • Mitochondria
  • Chloroplasts
  • Ribososmes
• Differentiation


  The process by which cells develop the structure and characteristics needed to be able to carry out their functions
• Multicellular organism development

  • Cells differentiate to form specialised cells
  • In animals, most cells differentiate at an early stage of development
  • Animal cells lose their ability to differentiate early in the life of the organism
  • Specific cells in various locations throughout the body of an animal retain the ability to differentiate throughout the life of the animal
• Adult stem cells


  Undifferentiated cells that retain the ability to differentiate throughout the life of the animal, mainly involved in replacing and repairing cells
• Plants


  • Many types of plant cells retain the ability to fully differentiate throughout the life of a plant, not just in the early stages of development
• Specialised cells


  Cells which have developed certain characteristics in order to perform particular functions, controlled by genes in the nucleus
• Cells specialise by undergoing differentiation
• Embryonic stem cells

  • Found on the inside layer of an embryo
  • They are undifferentiated
  • Produce all the different types of specialised cells in the body
• Adult stem cells

  • Found in the Bone marrow, skin, other organs and umbilical cord blood
  • They are partially specialised
  • Bone marrow and umbilical cord: produce blood cells
  • Skin: produce cells found in the different layers of the skin
  • Other organs: produce cells found in these organs
• Meristem cells

  • Found in the tips of shoots and roots
  • Fully undifferentiated
  • One cell has the ability to divide to produce a whole new plant
• Importance of stem cells:

  • Embryonic stem cells: form all the different tissues and organs needed to form a whole individual
  • Adult stem cells: replace damaged cells and produce new cells
  • Meristem cells: can differentiate into cells needed by the plant in regions were growth is occuring
• • Stem Cell Therapy: Using stem cells to treat or repair damaged tissues.
  • Bone marrow transplants treat patients with conditions like leukemia, as the healthy cells killed during chemotherapy can be replaced by stem cells from the bone marrow.
  • Embryonic stem cells can be cultured in a fertility clinic. We may be able to use them to treat diseases like diabetes and Parkinson’s disease and repair damaged nerve tissues.
• Stem Cell Therapy: Using stem cells to treat or repair damaged tissues.

  • Bone marrow transplants treat patients with conditions like leukemia, as the healthy cells killed during chemotherapy can be replaced by stem cells from the bone marrow.
  • Embryonic stem cells can be cultured in a fertility clinic. We may be able to use them to treat diseases like diabetes and Parkinson’s disease and repair damaged nerve tissues.
• Benefits:

  • Can replace damaged cells
  • Bone marrow transplants can treat diseases such as leukemia
  • Can grow whole organs for transplants
  • No rejection from stem cells from the patient itself
• Risks:

  • Ethical issues from destroying unused embryos
  • No guarantee of success
  • Possibility of mutations
  • Difficult to find stem cell donors