Science Learning intention To create a timeline to show the development and refinement of the cell theory You will need A pen and paper A digital device Lesson 6 challenge answer ID: 1042305
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1. Year 8Lesson 7 – cellsScience
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3. Learning intentionTo create a timeline to show the development and refinement of the cell theory.
4. You will need• A pen and paper.• A digital device.
5. Lesson 6: challenge answerRecipe for miceJan Baptiste van Helmont (1577–1644) wrote ‘for if you press a piece of underwear soiled with sweat together with some wheat in an open mouth jar, after about 21 days the odour changes and the ferment coming out of the underwear and penetrating through the husks of the wheat, changes the wheat into mice. But what is more remarkable is that mice of both sexes emerge (from the wheat) and these mice successfully reproduce with mice born naturally from parents? But what is even more remarkable is that the mice which came out were not small mice, but fully grown.’ The recipe was created before the invention of the microscope.Cells arise from pre-existing cells.A female egg cell is fertilised by a male sperm cell through sexual reproduction to produce a new cell which then divide into many more cells to produce a baby mouse.
6. Cell theory timelineDraw up a timeline and record the date and name of the scientist to show the history of the development of the cell theory.Underneath each scientist insert the contribution the scientist made to the cell theory.The dates, scientist names and their contributions are not in order in the table on the next slide.
7. Cell theory timeline1841 Robert Remak saw the biscuit-shaped blood corpuscles of a chicken.1842 John Goodsir described the nucleus of a cell as the reproductive organ of a cell.1674 Anton van Leeuwenhoek described small moving ‘animacules’ in algae.1833 Robert Brown described the nucleus in the cells of an orchid.1976 Gordon H. Sato and colleagues showed that different types of cells require different nutrients.1858 Professor Rudolf Virchow stated that ‘every cell originates from another existing cell like it’.1840 Martin Barry described the fertilised egg cell dividing into 2 cells, then 4, then 8 etc.1665 Robert Hooke examined very thin slices of cork under a compound microscope and saw many tiny compartments that reminded him of the cells monks lived in. He called them ‘cells’. He was actually seeing cell walls.1843 Martin Barry described a sperm and an egg cell of a rabbit.Early 1600s Zacharias Jansen made the first compound microscope.1939 Vladimir Zworykin invented the electron microscope to see complex structure of the cell.1838 Matthias Schleiden and Theodore Schwann The cell theory denotes, that all the plants and animals consist of cells and that the cell is the basic unit of life.1839 Theodore Schwann observed the cell membrane.1951 George Otto Gey grew cervical cells from cervical cancer cells taken from Henrietta Lacks. HeLa cells are still sometimes used today.1809 Charles-François Brisseau de Mirbel described vegetables as being made up of cells that shared extremely thin walls.1811 Ludolph Christian Treviranus and Johann Jacob Moldenhawer proposed that cells are separate units.1824 Henri Dutrochet declared, ‘The cell is the fundamental element of organisation’.
8. Example of timelineDescribed a sperm and an egg cell of a rabbit. Contribution to cell theory.Contribution to cell theory.
9. ReviewScience is dynamic. Scientific knowledge has changed peoples’ understanding of the world and is refined as new evidence becomes available. The cell theory has been refined over time as our ability to observe living things has improved with technology.The cell theory states: all living organisms are composed of cellsthe cell is the basic unit of lifecells arise from pre-existing cells (they are not derived from spontaneous generation).
10. Cell theory timelineClick on the green box to review the cell theory timeline.
11. ChallengeCan we see viruses under a microscope?
12. Key termsSexual reproduction: reproduction involving the fusion of gametes (for example, sperm and egg) to produce a new organism. Offspring inherit characteristics of both parents and are genetically different. Spontaneous generation: the notion that life can arise from non-living matter (believed until the 17th century).
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