bacteria. structure one celled organisms that occur alone or in chains or groups three basic shapes...
TRANSCRIPT
Structure
• One celled organisms that occur alone or in chains or groups
• Three basic shapes– Spheres, called cocci– Rods, called bacilli– Spirals, called spirilla
• Cell contains cytoplasm surrounded by cell membrane and cell wall
• Ribosomes in cytoplasm, too
Structure Continued
• Classified as prokaryotic because they don’t contain a membrane bound nucleus or other organelles
• Genetic material is found in its one circular chromosome in cytoplasm– Some have smaller circular piece of DNA called a
plasmid
Special Features
• Some bacteria have:– Thick, gelatin like capsule
around cell wall for protection and to help stick to surfaces
– Hair-like projections- help stick to surfaces
– Slime layer- enables bacteria to stick to surrounding surfaces and reduce water loss
– Flagella- whip-like tails that help bacteria move
Reproduction
• Fission- process that produces two new cells with identical genetic material to each other and that of the original cell
• Some bacteria exchange genetic material by lining up next to each other and exchanging DNA through a small tube
Obtaining Food and Energy
Producers• Some bacteria contain
chlorophyll or other pigments to make own food using energy from Sun
• Others use energy from chemical reactions
Consumers• Some break down dead
organisms to obtain energy• Others live as parasites of
living organisms and absorb nutrients from their host
Aerobic Vs. Anaerobic
Aerobe• Break down food and obtain
energy through respiration• Most bacteria (and us!)
Anaerobe• Organism adapted to live
without oxygen– Anaerobic bacteria live in
intestinal track of humans– Some bacteria cannot survive
when exposed to oxygen
Kingdoms
• Bacteria classified into two kingdoms– Eubacteria Scientists study many characteristics
to classify eubacteria into smaller groups– Archaebacteria contain bacteria found in
extreme conditions, such as hot springs
Cyanobacteria
• A eubacteria producer that makes own food using carbon dioxide, water, and energy from sun. produce oxygen as a waste. Live in colonies are an important food source for some organisms in lakes, ponds, and oceans. Oxygen produced by them is used by other aquatic organisms. However, can cause blooms that are harmful to organisms
Consumer Eubacteria
• Classified into two categories based on results of Gram’s stain– Bacteria treated with chemical called stain.
• Gram positive bacteria stain purple because they have thicker cell walls
• Gram negative bacteria stain pink because they have thinner cell walls– Composition of cell wall can determine how effective certain medicines
will be against the bacteria
• One group does not have cell walls, allowing them to change shape. One type of these causes pneumonia
Archaebacteria
• One group lives in salty environments like Dead Sea
• Others love hot or acidic environments, living near ocean vents or hot springs
Methane producers
• Some archaebacteria use carbon dioxide for energy and release methane gas as a waste.– They are used in sewage treatment by breaking
down the waste material that has been filtered out
Beneficial Bacteria
• Some bacteria produce chemicals called antibiotics that limit the growth of other bacteria
• Consumer bacteria called saprophytes uses dead organisms as food and energy sources– By helping to recycle nutrients, the nutrients
become available to other organisms
Nitrogen fixing bacteria
• Plants and animals need nitrogen to make proteins and nucleic acids– Plants need nitrogen from the soil or air
• Nitrogen-fixing bacteria change nitrogen from the air into forms that plants and animals can use– Some plants, like peanuts, have nodules that
contain these bacteria
Bioremediation
• Using organisms to help clean up environmental pollutants
• One type uses bacteria to break down wastes and pollutants into simpler harmless compounds– Oil spill cleanup by bioremediation likely to
increase in future
Bacteria and Food
• Bacteria used to make yogurt, cheese, and buttermilk
• Other foods made using bacteria are sauerkraut, vinegar, pickles, olives, soy sauce
Other Uses of Bacteria
• Medicines, enzymes, cleansers, adhesives
• Methane gas produced by bacteria used as fuel for heating, cooking, and industry, as well as breaking down plant and animal material
Harmful Bacteria
• Not all bacteria is good!• Pathogen- any organism that causes disease– Bacteria causes strep throat, whooping cough,
anthrax, botulism, and more
Bacteria and Toxins
• Some bacteria produce poisonous substances known as toxins– Ex: botulism a type of food poisoning that can cause
paralysis or death• When growing conditions unfavorable, bacteria
can produce thick-walled structures called endospores, which can exist hundreds of years before resuming growth– Commercially canned food undergo process that uses
steam at high pressure to kill bacteria and endospores
Pasteurization
• Unless it’s been sterilized, all food contains bacteria
• Pasteurization process of heating food to a temperature that kills most harmful bacteria but causes little change to taste of food– ex: milk, some fruit juice, yogurt all pasteurized
Treating Bacterial Diseases• Bacterial diseases usually
treated with antibiotics.– Penicillin, an antibiotic,
prevents bacteria from making cell walls
• Vaccines made from damaged particles taken from bacteria cell walls or dead bacteria. When vaccine injected, white blood cells recognize bacteria so that if it enters body again, white blood cells will attack it