1 / 7

Bacteria

Bacteria. REVIEW. Bacteria. Bacteria are single-celled organisms Are present in air, water and on most solid materials Bacterial cells are very small and can only be seen with the aid of a microscope. Bacterial Shapes.

pakuna
Download Presentation

Bacteria

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bacteria REVIEW

  2. Bacteria • Bacteria are single-celled organisms • Are present in air, water and on most solid materials • Bacterial cells are very small and can only be seen with the aid of a microscope.

  3. Bacterial Shapes • When observed under a microscope the cells can be seen to differ in shape and in conformation of groups of cells. • Cells are either spherical or rod-shaped • Spherical bacteria are called cocci • Those that are rod shaped are called bacilli. • This is the first basis for differentiating between bacterial cells.

  4. Rod-shaped & Spherical Bacteria • Bacteria are also classified according to cell cluster formation: • Diplococci * two cocci cells pairedStaphylococci * a number of cells clustered togetherStreptococci    * a number of cells arranged in a chain

  5. Bacterial characteristics • Some bacteria are capable of locomotion by means of flagellae • long, hair-like appendages growing out of the cell • Some rod-shaped bacteria contain spores • These are formed when the cells are faced with adverse conditions, such as high temperature • once suitable conditions are reestablished the spores germinate to form new cells.

  6. Bacterial Components • Close examination of the simple cell reveals that it is composed of the following components : • Cell wall-this gives the cell its shape and retains the constituents • Cell membrane-used for filtering in food constituents and discharging waste products • Nucleoid-where the genetic material of the cell is stored; • Cytoplasm- a semiliquid proteinaceous substance which contains starch, fat and enzymes.

  7. The cell membrane is semipermeable and allows the cell to feed by osmosis • i.e. the exchange of water between the cytoplasm of a living cell and the surrounding watery material. • Only small molecules can pass in and out of the cell • e.g. with a sugar solution on one side of a semipermeable membrane and water on the other, water will diffuse in, diluting the sugar solution. The sugar molecules cannot pass out so a hydrostatic pressure, known as osmotic pressure, develops. • Bacteria can feed by selective intake of nutrients dissolved in water. They can also take in nutrients against the normal osmotic flow • active transport.

More Related