2Characteristics Bacteria are smallest living organisms Bacteria consist of a single cellBacteria are nearly 3.5 billion years old. They are among the earliest forms of life that appeared on Earth.
3Bacterial Cell Bacterial cells are prokaryotic – they have no nucleus or other membrane-bound organellesBacterial cells have a single chromosome – a circular DNA moleculeBacterial cells have a cell wallMost bacteria reproduce by binary fission
4ClassificationBacteria fall into a category of life called the Prokaryotes. Prokaryotes' genetic material, or DNA, is not enclosed in a cellular compartment called the nucleus.Bacteria and archaea are the only prokaryotes. All other life forms are Eukaryotes, creatures whose cells have nuclei.
5What they look like?There are thousands of species of bacteria, but all of them are basically one of three different shapes.3. Spirilla are helical or spiral in shapeCocci are shaped like little balls2. Bacilli are rod- or stick-shaped
6What they eat? Autotrophs photosynthetic bacteria can make their own food from carbon dioxide using sunlight, just like plants.chemosynthetic bacteria produce their own organic compounds from inorganic substances such as iron or sulfur.Heterotrophsneeds organic substances that have already been assembled by autotrophs.
7Where they live?Bacteria live just about everywhere: in the soil, water and air; in animals, plants, rocks and even in us!Bacteria from boiling waterof hot springs in Yellowstone National ParkBacteria on our teeth
8SporesSpore (or endospore) is a dormant cell. It has a tough shell that insulates and protects the genes and basic cell parts.Spores are resistant to heat and cannot be readily destroyed, even by boiling.In 2000, scientists revived bacteria that had lain in suspended animation for 250 million years.
9Role of bacteria Negative: Bacteria can cause illnesses: Diarrhea Lyme diseaseBotulismLeprosyHow can you protect yourself and others from contamination by pathogenic bacteria?Wash up!
10Role of bacteria, cont. Positive: There are many important jobs bacteria do.They are used to make medicine.They break down oil from oil spills.They make about half of the oxygen we breath.They are the foundation of the food chain that feeds all life on earth
11Our Friends Bacteria do many good thins for us: Escherichia coli: one of many kinds of microbes that live in your gut. Wanted for helping you digest your food every day.Pseudomonas putida: one of many microbes wanted for cleaning wastes from sewage water at water treatment plants.Lactobacillus acidophilus: one of the bacteria gang wanted for turning milk into yogurt.Streptomyces: soil bacteria wanted for making streptomycin, an antibiotic used to treat infections.
12Questions What kind of medication are antibiotics? Why it is necessary to boil water before drinking?Why hospitals sterilize instruments in autoclaves?Escherichia coli is a normal resident of the mammalian gut. What is its role?Can bacteria sense and move?What are the cell shapes of Lactobacillus, Staphylococcus, Spirochaeta?
13Answer 1 Antibiotics fight diseases that are caused by bacteria. Bacteria are constantly changing and developing antibiotic-resistant strains.We need new antibiotics that can fight resistant strains of bacteria.
14Answer 2Drinking-water may be contaminated by a range of microbes that may pose risks to health1.8 million people die every year from diarrheal diseases (including cholera); 90% are children under 5, mostly in developing countries.High temperature kills the majority of pathogenic bacteria
15Answer 3 Boiling temperature is not enough to kill bacteria spores. An autoclave is designed to produce temperatures and pressures that will completely sterilize objects.
16Answer 4 E.coli : enhances digestion Impedes colonization of the gut by a variety of pathogensCan cause diarrhea (E.coli is the leading cause of infant mortality for most of the human population)
17Answer 5Bacteria sense light, detect the presence of oxygen and other chemical compounds. Magnetotactic bacteria have a chain of magnetite particles in their cytoplasm that serves as a tiny compass.Some bacteria move about their environment by means of long, whip-like structures called flagella.
19Interesting facts about bacteria Bacteria can live in temperatures above the boiling point and in cold that would freeze your blood. There's even a species of bacteria—Deinococcus radiodurans—that can withstand blasts of radiation 1,000 times greater than would kill a human being.They "eat" everything from sugar and starch to sunlight, sulfur and iron.
20Biggest BacteriumThe colossus among bacteria is a single-celled giant that lives in the ocean and is named Thiomargarita namibiensis , which means "sulfur pearl of Namibia." It was found in the ocean floor off the coast of Namibia in Africa. T. namibiensis’s ball-shaped cells can grow to almost 1 millimeter or 1/25th of an inch in diameter. That’s about as big as the period at the end of a sentence.
21Millions of them…Your body is home to trillions of microbes. Run your tongue over your teeth—you're licking thousands of microbes that normally live on your teeth. Millions of them live on your tongue, too. A large part of "you" (that is, the mass of your body) is actually something else: bacteria, viruses and fungi. Isn't that a weird thought?A single teaspoon of that soil contains over 1,000,000,000 bacteria,
22Bacteria on Mars?Some scientists even believe there is the possibility bacteria may have once lived on Mars. This photograph shows what some scientists believe may be the fossils of tiny bacteria in a rock that formed on Mars about 4.5 billion years ago.