Friday, January 18, 2008

The Unit of Life

1.The Cell
All living things are made of one or more cells. A cell is the smallest unit of life and all living things begin with a single cell.
Single-celled or unicellular organisms Paramecium is a microscopic unicellular organism that moves using hair-like structures called cilia and flagella. Amoeba is a microscopic unicellular organism that moves using pseudopods(false legs) Bacteria is also a microscopic unicellular organism that comes in various shapes such as spherical, rod-like or spiral and can live in clusters. Also check out how big they are. Yeast are very economically useful organism used in baking and brewery industries. They need food to eat and produces carbon dioxide, which causes dough to 'rise'. Many-celled or multicellular organisms These organisms are made up of more than one cell For Example: Plants, Animals, Fungi such as mushroom
2. Parts of a cell
You have observed an example of an animal cell-the human cheek cell. You have also observed 2 different types of plant cell: the onion cells and Elodea cells. One is photosynthetic because it contains chloroplasts.
3. Producing New cells
Cells increase in number by a process called cell division. Both unicellular and multicellular organisms undergo cell division. Unicellular organisms reproduce either by cell division or budding. In cell division, the nucleus and the cytoplasm of a parent cell divide to form 2 identical daughter cells which then in turn divides further to form more cells.
For example yeast undergo budding.
Notice the parent cell buds and forms another, smaller daughter cell.