Biology 1 : Cell Biology

Cell Structure
1. Eukaryotes and Prokaryotes
  1. Prokaryotic Cells
    1. No nucleus and DNA is free to move
    2. e.g. Bacteria and Archaea Cells
    3. No organelles but have ribosomes
  2. Eukaryotic Cells
    1. DNA is kept in nucleus
    2. e.g. Plant and Animal Cells
    3. Membrane-bound organelles
2. Animal and Plant Cells
  1. Plant Cell
    1. Only two extra adaptations from animal cell
    2. Cell Wall
      1. Protection and structure
    3. Vacuole
      1. Storage of cell sap
  2. Animal Cell
    1. Nucleus
      1. Controls cell activity
    2. Mitochondria
      1. Releases energy (aerobic respiration)
    3. Cytoplasm
      1. Chemical reaction site
    4. Ribosomes
      1. Protein synthesis
    5. Cell Membrane
      1. Entry and exit of substances
3. Microscopes
  1. Magnification : the enlargement of something by an optical instrument
  2. Resolution : increasing the detail we can see
  3. Cell Size
    1. Actual size = Image size/Magnification
4. Specialised Cells
  1. Animal Cells
    1. e.g.
      1. Sperm Cells : tail for movement
        Male sex cell (reproduction)
        Long tail for movement
      2. Nerve Cells
        Create pain to warn you of danger
        Branches that connect to other nerves
      3. Muscle Cells : able to change shape
        Allows movement in body
        Able to change shape
    2. differentiate at an early stage
  2. Plant Cells
    1. keeps ability to differentiate
    2. e.g.
      1. Xylem
        Carries water from roots to leaves
        Nothing inside to get in the way
      2. Phloem
        Carries glucose
        Only lets glucose through
      3. Root Hair Cell
        Collects water
        Large surface area
Cell Division
1. Chromosones
  1. Nucleus of a cell contains chromosomes made of DNA
  2. Every chromosome carries a large number of genes
  3. Body cell chromosomes are usually in pairs
2. Cell Cycle
  1. 1. Genetic material is doubled and divided into two cells
  2. 2. Before diving the sub-cellular structures increase and DNA is duplicated
    1. (Ribosomes and Mitochondria)
  3. 3. In mitosis the chromosomes are divided and pulled to each end of the cell and nucleus divides
  4. 4. The cytoplasm divides and two identical cells are made
3. Stem Cells
  1. Starts as an undifferentiated cell
  2. Can be cloned to make new human cells
    1. These aren't rejected from human bodies so they can be used for medical reasons
  3. Can be collected from adult bone marrow
    1. These can make any kind of cell
  4. Meristem tissue can be collected from plants
  5. Can help diabetes or paralysis
  6. Plant stem cells can efficiently reproduce plants
    1. e.g. endangered or useful plants
  7. Could cause infection or ethical reasons could get in the way
Transport in Cells
1. Diffusion
  1. Substances can move in and out of cells
  2. The spreading of particles in a solution or in particles of gas
    1. High to low concentration
  3. CO2 and O2 are exchanged in the body
  4. Waste products are exchanged at the kidneys
  5. Factors that affect rates of diffusion :
    1. Concentration gradient, larger means faster
    2. Temperature, hotter means faster
    3. Surface area of the membrane, larger means faster
2. Active Transport
  1. Low to high concentration
    1. Needs energy from respiration
  2. Mineral ions can be absorbed from soil into roots, plants need ions for growth
  3. Sugar can be absorbed from gut into blood and the sugar is used for respiration
3. Osmosis
  1. Movement of water across cell membranes
  2. The diffusion of water from dilute to concentrated through a partially permeable membrane
  3. High to low concentration

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Biology 1 : Cell Biology

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