1. Organisms are made of cells that have similar structural characteristics
OUTLINE THE HISTORICAL DEVELOPMEMT OF THE CELL THEORY, IN PARTICULAR, THE CONTRIBUTIONS OF ROBERT HOOKE AND ROBERT BROWN
In 1665 Robert Hooke observed cork cells using a compound microscope and described ‘little boxes or cells distinct from one another’
In 1831 Robert Brown observed the nucleus in plant and animal cells
The Cell Theory;
1. Cells are the smallest units of life (Schwann, Schleiden – 1839)
2. All living things are made up of cells (Schwann, Schleiden – 1839)
3. All cells come from pre-existing cells (Rudolf Virchow – 1839)
DESCRIBE EVIDENCE TO SUPPORT THE CELL THEORY
Robert Hooke’s observation of cork cells, and Leeuwenhoek’s observations of many types of unicellular cells proved that living things were made up of cells
Walter Flemming’s observation of cell division – mitosis – proved that cells come from pre-existing cells
Supported more as more people began to observe cells and their processes
DISCUSS THE SIGNIFICANCE OF TECHNOLIGICAL ADVANCES TO DEVELOPMENTS IN THE CELL THEORY
Technological advances have added to our knowledge of cells
Staining techniques had an ability to cut thing sections of tissues from multi-cellular organisms revealed cell structures
Different coloured dyes are taken up by different organelles, which allows for easy identification of organelles
Electron microscope (1933) allowed for more detailed observations
Laser scanning and use of 3D imaging software have improved our knowledge
X-ray microscopes allow the shape and structure of biological molecules to be identified
IDENTIFY CELL ORGANELLES SEEN WITH CURRENT LIGHT AND ELECTRON MICROSCOPES
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DESCRIBE THE RELATIONSHIP BETWEEN THE STRUCTURE OF CELL ORGANELLES AND THEIR FUNCTION
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2. Membranes around cells provide separation from and link with the external environment
IDENTIFY THE MAJOR GROUPS OF SUBSTANCE FOUND IN LIVING CELLS AND THEIR USES IN CELL ACTIVITIES
Organic compounds: Contain carbon and are large molecules. The main ones found in cells are; proteins, carbohydrates, lipids and nucleic acids
Inorganic compounds: Do not contain carbon and are found in living and non-living things. They include; mineral salts, water, oxygen, carbon dioxide, sodium and potassium
Use in Cell
WATER
- H2O
- Solvent for many substance
- Participates in reactions
- Stabilises temperature within cells
- Involved in the transport of substances within and between cells
SODUIM CHLORIDE
- NaCl
- Involved in control of water cells
- Operation of cell membranes
- Helps in the function of nerve and muscle cells
CARBON DIOXIDE
- CO2
- Used by almost all cells in process of respiration
NUCLEIC ACIDS
(Nitrogen, Phosphorus, Carbon and Hydrogen)
- DNA: Stores genetic material, which defines the structure and function of cell, DNA is in most chromosomes
- RNA: Involved in transferring information from chromosomes ribosomes and in using transferred info to construct proteins
PROTEINS
(Carbon, Hydrogen, Oxygen, Nitrogen)
- Contribute to cell structures such as membranes
- Composed of ‘building blocks’ – amino acids, which have a complex 3D structure
CARBOHYDRATES
(Carbon, Hydrogen, Oxygen and Nitrogen)
“Hydrates of Carbon”
- Simple Sugars (Monosaccharides): Such as glucose, fructose and galactose are ‘building blocks’ for more complex materials. Glucose is used in respiration and photosynthesis
- Double Sugars (Disaccharides): Such as sucrose, lactose and maltose are the ‘building blocks’ and are often transported between cells
- Complex Sugars (Polysaccharides): Such as starch, glycogen and cellulose are energy (starch in plants and glycogen in animals) and for cell structure in cell walls
LIPIDS
(Carbon, Hydrogen, Oxygen and sometimes Nitrogen)
- Fats and oils: Store energy, made from glycerol and fatty acids and are saturated or unsaturated
- Waxes: Contribute to structure, eg. of the cell wall, made from acids and molecules larger
