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Unit Two: Reproduction

Explore the fascinating world of cells, from genetic information in the nucleus to the function of organelles. Learn about similarities and differences among species using microscopy and discover the essential components of all cells. This educational unit covers cell structures, functions, and the role of genes in determining characteristics.

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Unit Two: Reproduction

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  1. Unit Two: Reproduction Science 9

  2. Cellular Processes • Students will be expected to: • Recognize that the nucleus of a cell contains genetic information and determines cellular processes

  3. First Five Minutes • Look around the classroom and observe, note and report differences and similarities among members of the class • Physical traits such as hair and eye colour, attached/detached ear lobes, tongue rollers/non-rollers “What causes people to be the same and yet different?” “Are there similarities and differences in other species?”

  4. Who started describing cells and a nucleus? • The cell was first described by Robert Hooke in 1665 while he was looking at cork under a microscope • He was really looking at cell walls, not cells • Anton van Leeuwenhoek observed living cells in blood, bacteria and single-celled organisms • Robert Brown was the first to describe a nucleus in plant cells (1820); it was also discovered in animal cells a few years later

  5. What are cells? • Schwann and Schleiden concluded that plants and animals are composed of cells • All living things are composed of one or more cells • The cell is the functional unit of life • Most cells have to be seen with the aid of a microscope

  6. Light Microscopes • Uses light and multiple lens to see small organisms and cells

  7. Light Microscopes

  8. Electron Microscopes • Uses beams of electrons, limited to only looking at a single layer of cells but with much more magnification than light telescopes • Only dead cells can be observed

  9. Transmission Electron Microscope

  10. Scanning Electron Microscopes • Uses reflection by electrons hitting the surface of the cell • Produces a three dimensional image

  11. Scanning Electron Microscope

  12. Images of Cells • What we can see under a microscope as far as the cell goes has helped us to create a model of what a cell looks like with all its parts. This is a plant cell.

  13. Animal Cells

  14. What is common among all cells? • The entire cell is covered with a cell membrane which controls what goes into and out of the cell • The nucleus acts as a control centre, directing the cell’s activities • Genetic information is organized into threadlike structures called chromosomes • Each chromosome contains different genes • Genes are units of genetic information that determines the specific characteristics of an individual

  15. Continued… • The cytoplasm is the area where work is done • Nutrients are absorbed, transported and processed • It contains many different organelles, which is a specialized structure inside the cell

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