Bacteria

Cells Eukaryote: An organism with cells that contain a nucleus and other cell structures Prokaryote: An organism whose cells lack a nucleus and other cell structures Bacteria are prokaryotes Plants and animals are eukaryotes Prokaryote Cell Eukaryote Cell

Prokaryotes  Bacteria Bacteria are prokaryotes. Their genetic material is NOT contained in a nucleus. Bacteria, under a microscope, have 3 possible shapes. The different shapes help identify the type of bacteria. 1. Spherical 2. Rodlike 3. Spiral

Structure of Bacteria Cells Cell Wall-helps protect the cell Cell Membrane-Controls which materials pass into and out of the cell Cytoplasm- Gel-like substance located inside the cell membrane Ribosomes- Tiny structures found in cytoplasm that produce proteins NO NUCLEUS… rather, bacteria cells have genetic material Flagellum- Long whip-like structure that helps the bacteria cell move Genetic material

Two Kingdoms of Bacteria 1. Archaebacteria – “Ancient Bacteria” Existed on Earth BILLIONS of years before Dinosaurs Live in extreme environments (examples: salt water, acid, hot springs etc.) 2. Eubacteria Do NOT live in extreme environments… they live EVERYWHERE else Millions of eubacteria live in and on your body… but most of these are harmless to you Help maintain Earth’s physical conditions. For example, Oxygen level

Bacteria Reproduction When bacteria have plenty of food, the right temperature, and other optimal conditions, they reproduce frequently (sometimes once every 20 minutes!!!) Bacteria reproduce by “Binary Fission”: 1 cell divides to form 2 identical bacterial cells Binary Fission is a form of asexual reproduction (1 parent produces offspring that are identical to the parent) Some bacteria can sexually reproduce (2 parents combine their genetic material to produce a new organism that is different from each parent) through a process called “conjugation” Conjugation is where 1 bacterium transfers its genetic material to another bacterium through a tiny bridge

Bacteria Bacteria must have: 1. Food – Some bacteria are “autotrophs”, they make their own food; Other bacteria are “heterotrophs”, they get their food from consuming autotrophs and other heterotrophs. 2. Respiration (breaking down food into energy) – Most bacteria need oxygen to break down their food into energy Some have: Endospores. Endospores are small, round, think-walled resting cells that form inside a bacteria. They contain the genetic material and some cytoplasm. Endospores can survive harsh conditions like freezing, heating and drying.

Bacteria… good or bad?? It’s true, some bacteria cause harmful sicknesses and diseases, spoil food, etc. BUT… most bacteria are either harmless or helpful to humans!!! 1. Fuels and natural gasses 2. Natural Recyclers – bacteria are decomposers; they break down dead organisms into chemicals that other organisms can use. For example: dead leaves in autumn 3. Help clean up the environment i.e. oil spills 4. Create medicines and keep your body healthy by preventing the harmful bacteria from making you sick 5. FOOD!!!!

Food Preservation Food preservation methods create conditions that kill or slow down the bacteria so that food does not spoil 1. Dehydration or Salting – reduces water activity to prevent bacterial growth 2. Vacuum-Packing – Food is stored in air-tight containers where 55is NO oxygen (remember…Bacteria need Oxygen to live) 3. Pickling – Food is placed in an edible liquid that inhibits or kills bacteria(pickles) 4. Freezing – Most harmful bacteria cannot grow in extremely cold temperatures 5. Irradiation – Exposing the food to X-rays and other radiation forms to kill bacteria