AS Biology OCR note

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AS Biology OCR note
2011-04-02 09:32:55
Biology OCR

Overview of biology, both unit 1 and 2
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  1. There are 2 basic cell types:
    Prokaryotic: bacteria and cyanobacteria and Eukaryotic: all other cells e.g. protoctista, fungi, plant and animal cells
    • Features of Prokaryotic Cells: Are 0.5 - 5µm, they have a cell wall that contains peptidoglycan, Its genetic material of DNA is naked, it is a single circular molecule, has 70S ribosome’s (smaller). Contains no organelles such as ER, Golgi apparatus or Mitochondria (respiration occurs on an infolding of the cell membrane called the mesosome.)

    Feature of Eukaryotic cells; which are Plant or Animal cells, Plant cells are 40µm in size and Animal cells are 15µm. Plant cells have a cell wall which contains cellulose and also has chloroplast whereas Animal cells do not. Both Plant and Animal has DNA which is linear and associated with histones (proteins), in a nucleus, surrounded by a nuclear envelope. 80S ribosomes (larger), both contain organelles such as E.R, Golgi apparatus and mitochondria.
  2. Organelles are parts of the cell and most of them are surrounded by membranes. Both animal and plant cells have cell membrane, centrosome, cytoplasm, Golgi body, lysosome, mitochondrion, nuclear membrane, nucleolus, nucleus, ribosome, rough endoplasmic reticulum and smooth endoplasmic reticulum. However Plant cells also contain a cell wall, vacuole and cholorplast.
    Cell membrane:
  3. Organelles in a Animal and Plant Cell