Biology – Pattern in Nature
Organisms are made of cells that have similar structural characteristics
Outline the Historical development of the cell theory, in particular, the contributions of Robert Hooke and Robert Brown. •
1665 English scientist Robert Hooke used microscope to examine thin slices of cork and saw small box-like compartments he called cells. He was first to realise plant material had organised structure at microscopic level. (compound microscope) •
1831 Scottish Botanist Robert Brown was involved in a dispute about how pollination and fertilisation occurred in plants. During his study with orchids, he noted that ‘Each cell has a spherical structure’. He named it the nucleus of a cell. First to introduce the concept of a nucleated cell as unit of structure in plants.
Describe evidence to support the cell theory.
Cell theory evidence accumulated over 600 years with advancement of technology with the microscope and lenses. •
14th century Italian monks invented magnifying glass spectacles. •
1590 first two lens/ compound microscope made by Hans and Zacharias Janssen. •
1676 Leeuwenhoek (Dutch) saw micro organisms under a microscope in a drop of pond water. •
1824 Henri Dutrochet (French) suggested that all organisms are composed of cells. •
1838 Schleiden and Schwann (German) further advanced idea that all organisms are made of cells. Increasing evidence. E.g. first researcher to view single yeast cells budding and producing new cells. From that time on, cells regarded as building block of life. •
1859 Rudolph Virchow (German) stated that all cells divide and that is how new cells are made. •
1879 Walther Flemming (German) used biological stains to view cells dividing and verified the ideas of Virchow.
Discuss the significance of technological advances to developments of cell theory •
Middle ages- Spontaneous generation- meat + maggots, tadpoles/frogs in H20. (Living matter arises from non-living matter....
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