Cell jot notes 1.11 – 1.15

1. Cell jot notes 1.11 – 1.15

2. Tissues • A group of cells that are similar in shape and function is called a tissue • Tissues are often organized into larger structures called organs • Organ systems are group of organs that have related functions • Unicellular organisms are one-celled organisms (e.g. Amoeba) • Multicellular organisms are many celled organisms(e.g. man) • Micro-organisms are living things that can be seen only with the aid of a microscope.

3. Unicellular Organisms • Bacteria : They are the most primitive and also the most plentiful organisms on the planet. They are different from plant and animal cells in that they have no nucleus , no mitochondria and no ribosomes . • Protists : They are found almost anywhere there is water , even in moist soil or in rotting leaves. Unlike bacteria , protists have a nucleus and contain organelles such as the mitochondria, ribosomes and lysosomes.

4. Plant like Protists • 1) Diatoms: Are found in both fresh and salt water. They contain chlorophyll and can make their own food. • 2) Euglena: Euglena is like both a plant and an animal cell. If there is lots of sunlight , euglena acts like a plant and makes its own food. With reduced sunlight , euglena acts like an animal and begins feeding upon smaller cells.

5. Animal -like Protists • 1) Amoeba : As the amoeba moves, it changes shape. These blob like organisms moved by pseudopod (false foot). The pseudopod anchors to an object, and the rest of the cell is dragged toward it. • 2) Paramecium: Tiny hair like structures, called cilia, beat together to create water currents that move the paramecium. There are also cilia around the paramecium's oral groove. Bacteria and other smaller cells are the main food source for paramecia ( plural) • 3) Fungus: Fungi include many organisms that are multicellular. Bread, mould, mushrooms and puff –balls are well known fungi. Harmful fungi include those that cause ringworm , athlete’s foot . Yeast is one of the few unicellular fungi. There are many different species of yeast. Like animal cells , yeast cell do not have chlorophyll and must rely on other organisms for their source of energy.

6. Cell Specialization • Unicellular organisms are not specialists. Each cell must carry out all the functions of life. Multicellular organisms, such as Man, benefit from cell-specialization. • The spaces between plant cells are referred to the lamellae, they contain a sticky , sugary substance called Pectin • Pectin acts like cement, sticking plant cells together.

7. The End