Biology Unit 2.1-Cells,Tissues and Organs

Animal Cells and Plant Cells
1. Animal Cells
  1. Nucleus, Mitochondria, Cell Membrane, Cytoplasm, Ribosomes.
2. Plant Cells
  1. Nucleus, Mitochondria, Cell Membrane, Cytoplasm, (Permanent vacuole), (Chloroplasts), Cell Wall, Ribosomes.
3. Nucleus- controls all the activities of the cell. They carry the instructions for making new cells or new organisms.
  1. Cytoplasm- a liquid gel in which most of the chemical reactions needed for life take place.
  2. Cell Membrane- controls the passage of substances into and out of the cell.
  3. Mitochondria- structures in the cytoplasm where oxygen is used and most of the energy is release during respiration
  4. Ribosomes- where protein synthesis takes place. All of the proteins needed in the cell are made here.
  5. Chloroplasts- absorb light energy to make food my photosynthesis. Found in the green chlorophyll.
  6. Cell Wall- made of cellulose that strengthens the cell and gives it support.
  7. Permanent Vacuole- a space in the cytoplasm filled with cell sap. Keeps the cell rigid
Bacterial Cells
1. Don't have a nucleus, instead the genetic material is suspended in the cytoplasm.
  1. Extra DNA within the cell are called plasmids.
2. Some bacteria have flagella, which are long protein strands that propel it forward.
Yeast Cells
1. Bigger than bacteria but still very small.
2. Can respire aerobically and anaerobically.
  1. When yeast cells break down sugar in the absence of oxygen, they produce ethanol and carbon dioxide. This process is known as fermentation.
3. Nucleus, Cell Wall, Cell Membrane, Cytoplasm.
Specialised Cells
1. Fat Cells
  1. Small amount of cytoplasm and large amounts of fat.
  2. Few mitochondria as the cell needs very little energy.
  3. They can expand up to 1000 times its original size.
2. Cone Cells
  1. In the human eye, in the light sensitive part, the retina.
  2. Outer Segment contains special chemical which changes chemically in coloured light.
  3. Middle segment is packed full of mitochondria, which release energy needed to reform the pigment. This allows you to see continually in colour.
  4. Final part is a specialised synapse that connects to an optic nerve. When coloured light makes your visual pigment change, an impulse is triggered. The impulse crosses the synapse and travels along the optic nerve to your brain.
3. Root Hair Cells
  1. Increase the surface area for water to move into the cell.
  2. Large permanent vacuole that speeds up the movement of water by osmosis from the soil across the root hair cell.
4. Sperm Cell
  1. Long tail propels them forward.
  2. Middle section is full of mitochondria which gives the tail energy to work.
  3. Acrosome stores digestive enzymes for breaking down the outer layers of the egg.
  4. Large nucleus contains the genetic information to be passed on.
Diffusion
1. Is the movement of particles from an area of high concentration to an area of low concentration.
  1. The bigger the difference, the steeper the concentration gradient.
  2. Surface Area:Volume effects the rate of diffusion. Cell membranes or linings of organs that are folded have an increased surface area. Therefore the rate of diffusion is greatly increased.
Tissues and Organs
1. A tissue is a group of cells with similar structure and function working together.
  1. Muscular, Glandular, Epithelial, Epidermal, Mesophyll, Xylem, Phloem.
2. Organs are made up of tissues e.g stomach.
  1. Muscular tissue to churn the food and digestive juices of the stomach together.
  2. Glandular tissue to produce the digestive juices that break down the food.
  3. Epithelial tissue which covers the inside and outside of the organ.
Organ Systems
1. The Digestive System
  1. Is a muscular tube that squeezes your food through it. It starts at the mouth and finishes at the anus. There are many different organs in the digestive system, and there are glands such as the pancreas and salivary glands. These produce and release digestive juices to break down the food.
    1. The stomach and the small intestine are the main organs where food is broken down and digested.
      1. Enzymes break down the large insoluble food molecules into smaller, soluble ones.
      2. The small intestine is also where the small, soluble molecules are absorbed into the blood. Once they are there, they are transported in the blood stream around the body.
        The small intestine is adapted to have a very large surface area. this increase the rate of diffusion from the gut to the blood.
2. Plant Organs
  1. Have differentiated cells that form specialised tissues. (Mesophyll, xylem, phloem).
    1. Each organ carries out a specific job.
      1. Phloem transports dissolved food.
        Mesophyll tissue carries out photosynthesis.
        Xylem transports water and minerals.

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Biology Unit 2.1-Cells,Tissues and Organs

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