Cells

• Nucleus controls cell activities and contains DNA
• Cytoplasm is where chemical reactions take place
• cell membrane controls what goes in and out of the cell
• mitochondria is where respiration take place to release energy from glucose
• Ribosome is where protein synthesis take place
• cell wall gives shape and support , made of cellulose
• chloroplast contains chlorophyll for absorbing sunlight for photosynthesis
• vacuole contains cell sap for storing water and minerals
• Flagellum allows the cell to move
• Cell wall (bacteria) gives shape and support which is not made of cellulose
• Plasmid DNA is loops of DNA that can be swapped between bacteria
• A sperm cell is used to carry the Father's genetic information to the egg
• Adaptation : Sperm cell

  • The small cytoplasm makes the head streamlined to reduced drag when moving
  • The acrosome contains digestive enzymes to break down the outer layers of the egg
  • The large nucleus contains Genetic information
  • The middle section contains lots of mitochondria where respiration take place to release energy needed for the flagellum to move
  • A long flagellum (tail) which whips from side to side to allow the sperm to move
• A red blood cell carries oxygen around the body

  
• A sperm cell is used to carry the Father's genetic information to the egg

  
• Adaptation : Red blood cell

  • Biconcave shape gives a larger surface area to volume ratio to increase diffusion of oxygen in and out of the cell
  • Haemoglobin binds to oxygen to form oxy-haemoglobin so oxygen can be transported. In tissues, this reaction is reversed so oxygen is released
  • No nucleus to make more space for haemoglobin
• White blood cells destroy pathogens
• Adaptation : White blood cell

  • Lymphocytes makes and release antibodies which can destroy pathogens
  • Lymphocytes can also make antitoxins against any toxins made by pathogens
  • Phagocytes engulf ( surround ) and digest pathogens
• Root hair cell is used to absorb water and minerals from the soil

  
• Adaptation : Root hair cell

  • Hair increase the surface area available for movement of water and minerals into the cell
  • Thin cell wall so there is less distance for substances to move over
  • Large permanent vacuole that speeds up movement of water by osmosis
  • Lots of mitochondria to provide energy needed for active transport of mineral ions
• Xylem is used to carry water and dissolve mineral ions up the plant and provide support for the stem

  
• Adaptation : Xylem

  • Xylem start as living cells, but then die to form hollow tubes to allow water and minerals to move easily through them
  • Lignin builds up in spirals in the cell walls whilst the cells are alive. Once dead the lignin makes the cell very strong to withstand pressure of water moving
  • Strong lignin also helps support the plant
• Phloem is used to carry food (glucose) around the plant

  
• Adaptation : Phloem

  • Cell walls between cells break down to form sieve plates. These allow dissolved food to move up freely up and down the tubes
  • Companion cells. Phloem are mostly empty cells (without many of their own organelles) so the companion cells help keep the phloem cells alive
  • Companion cells have a lot of mitochondria to provide energy which is transferred to phloem to help move food up and down the plant
• Palisade cells absorb light energy and carry out photosynthesis

  
• Adaptation : Palisade cell

  • Tall and thin so lots can be packed into a leaf and it gives a large surface area for absorbing light.
  • Lots of chloroplasts, filled with chlorophyll for absorbing light energy and carrying out photosynthesis
• What is a stem cell?

  An undifferentiated cell which can differentiate into specialised cells
• What can stem cells from embryos do?

  They have the potential to turn to any kind of cell at all
• What can stem cells from adult bone marrow do?

  They can't turn into any kind of cell but only certain ones like a red blood cell or a white blood cell
• What can we use stem cells to treat?

  Diseases, replace faulty blood cells, make insulin-producing cells for people with diabetes and can also help nerve cells from paralysis
• What is therapeutic cloning?


  Its an embryo that could be made to have the same genetic/genes. This means the stem cells from embryo won't be rejected when they are used to replace faulty cells.
• What are the risks of using stem cells?

  Stem cells can be contaminated with a virus as they are grown in a lab
• What is a plant meristem?

  It is parts of a plant where growth occurs
• Embryo advantages:

  1. Can grow many embryos in a lab
  2. Can treat many diseases
  3. Painless technique
• Embryo disadvantages:

  1. Death to embryo
  2. Embryo cannot give consent
  3. Unreliable technique
• Adult embryo advantages:

  1. No ethical issues
  2. Can treat some diseases
  3. Safe procedure to obtain stem cells
  4. Reliable and patients recover quickly
• Adult embryo Disadvantages:

  1. Risk at infection
  2. Can only treat a few diseases
  3. Procedure can be painful
• What's an interphase? (Mitosis)

  In an interphase the cell grows bigger and makes more organelles
• Mitosis is a type of cell division producing 2 genetically identical daughter cells, it is used to make new cells for growth and repair
• What is an eukaryotic?

  It is a cell with a nucleus