AQA Biology B2 Unit 2.1 - Cells Tissues and Organs

AQA Biology B2 Unit 2.1 - Cells Tissues and Organs

1. Animals and Plant Cells

   • All little things are made up of CELLS
     • The Cell is the basic structural, functional and biological unit of all known living organisms
     • Cells are small and can only be seen with microscopes
   • Animal Cells have:
     • NUCLEUS
       • Contains the genetic material of the cell and controls the cell's activities
     • CYTOPLASM
       • Water-based gel which allows chemical reactions to take place within the cell. Controlled by enzymes
     • CELL MEMBRANE
       • Controls the movement of materials in and out of a cell
       • Holds the contents of the cell together
     • MITOCHONDRIA
       • This is where energy is released during aerobic respitation
     • RIBOSOMES
       • Where protein synthesis takes place
   • Plant Cells have:
     • CELL WALL
       • Made of CELLULOSE for support and structure of the cell. Strengthens the cell.
     • CYTOPLASM
       • Water-based gel which allows chemical reactions to take place within the cell. Controlled by enzymes
     • CELL MEMBRANE
       • Controls the movement of materials in and out of a cell
       • Holds the contents of the cell together
     • NUCLEUS
       • Contains the genetic material of the cell and controls the cell's activities
     • CHLORPLASTS
       • Contains CHLOROPHYLL, which asorbs light energy for photosynthesis
     • VACOULE
       • Filled with cell sap to keep the cell TURGID
         • CELL SAP: a weak solution of sugar and salts

2. Bacteria and Yeast

   • Bacteria
     • Very small and can only be seen by powerful microscopes
     • Bacterial cells have a CELL MEMBRANE and CELL WALL which surrounds CYTOPLASM
     • Do not contain a NUCLEUS so therefore all genetic material is found in the CYTOPLASM
     • When bacteria multiply they form BACTERIA COLONIES which can be seem by the naked eye
       • BACTERIA COLONIES: A population of billions of bacteria grown in culture
     • Examples
       • Lactobacillus Bularicus - A rod shaped bacterium used to make yoghurt from milk
       • Pneumococcus - A spherical bacterium that acts as the pathogen that causes pneumonia
     • BACTERIA: A single-celled microorgansim that can reproduce very rapidly. Many bacteria are useful (for example, gut bacteria and decomposing bacteria) but some can cause disease
   • Yeast
     • A single celled organsim
     • Have a nucleus, cytoplasm and a membrane surrounded by a cell wall

3. Specialised Cells

   • As an organsim matures each cell develops into a particular type. The structure of the cell is linked to the function
   • Sperm Cells
     • Has many mitochondria so that it has more energy
     • Has a tail so that it is able to move
     • The head contains genetic material and enzymes to help penetrate the egg cell membrane
     • It's function is to fertilise an egg cell - female gamete
   • Muscle Cells
   • Gland Cells
     • Has many Ribosomes so that it is making a lot of protein
   • Leaf Cells
   • Root Hair Cell
   • Red Blood Cells
     • Absorbs water and mineral ions from the soil
     • Thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. No nucleus, so the whole cell is full of Haemoglobin

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