Bacteria

Remember they are everywhere!In your food (yogurt), air (germs) on your body (remember our video?)

Anton van Leeuwenhoek found them by accident. Remember him?

• Bacteria are prokaryotes. The genetic material in their cells is not contained in a nucleus. They do not have a nucleus.

• Bacteria also lack many other structures that are found in eukaryotic cells.

What does a bacteria have?• DNA-tangled string• Cell wall-rigid and protective• Cell membrane-controls what goes in and out.• Cytoplasm-jelly-like material• Ribosomes-makes proteins• Flagellum-helps with movement—if there is not a flagellum then the

bacteria cannot move on their own—air, water, or objects move them.

Bacterial shapes

• Three basic shapes:• Spherical---------------------

• Rod-like----------

• Spiral---------------------------

Sizes of bacteria

• Vary greatly• The biggest is about the size of a period at the

end of a 12-font size.

• Average is much smaller. Strep bacteria is 0.5-1 micrometer in diameter. A micrometer is one millionth of a meter!

Thiomargarita namibiensis

Obtaining Food and Energy

• Bacteria must have a source of food and a way of breaking down the food to release its energy= Respiration

• Some are autotrophs and make their own food.• Some use chemicals from the environment. Like

those that live in hot springs in Yellowstone Park.• Some are hetertrophs and must consume other

organisms or food—from milk and meat or decaying leaves on a forest floor.

Respiration

• Remember that respiration is a process of breaking down food to release its energy.

• Some bacteria do not breath oxygen so they would die in the presence of oxygen.

What is Bacteria’s Role in Nature?

• Bacteria are not all bad—they are involved in oxygen and food production, environmental recycling and cleanup, and also in health maintenance and medicine production.

Oxygen

• Bacteria that are autotrophs produce oxygen as a waste product and put it back into the atmosphere—like a plant does.

Food Production uses of bacteria

• Cheese• Sauerkraut• Pickles• Apple cider vinegar• Buttermilk• Yogurt• Sour cream

What is pasteurization ?

• Louis Pasteur was the inventor.

• Food or beverages are heated to a temperature that is high enough to kill most harmful bacteria w/o changing the taste of the food.

Environmental Recycling

• The use of decomposers to break down the dead organisms into small chemicals are “nature’s recyclers.

• They live in the soil.• Some bacteria prefer oil and cleanup oil spills.

Health and Medicine

• Bacteria live in your intestines and help you digest your food. Some make vitamins for you.

• Others take up space so harmful bacteria cannot attach to your intestines and make you sick.

• Some are used to produce insulin for diabetics.

By the way—how does a vaccine work?

• By having the vaccine introduced into your body---it stimulates your body to produce chemicals that destroy specific viruses or bacteria.

• Vaccines are made from dead or altered viruses or bacteria so they cannot cause the disease but activate your body’s natural immune defenses.

• They put your body on alert so it will “destroy” if the germ enters your body.

What about antibiotics?

• These are chemicals that can kill bacteria without harming you or your cells!!

• They are naturally made by some bacteria and fungi. Penicillin weakens the cell walls of some bacteria and the cell burst!!

OK—so what is antibiotic resistance?

• This results when some bacteria are able to survive in the presence of an antibiotic and

they become “super bugs”!• Tuberculosis caused a problem• In 1940’s cases dropped but then• some resistant bacteria lived• and the cases increased over • the following 20 years.

Do you think this antibiotic resistance is a problem today?

•Yes!!

• How does it occur—you know strong bacteria survive but also-------

• If you stop taking antibiotics before the dose is complete=stronger bacteria also survive, can mutate and become stronger so—take the complete course of your medicine!!

What is the final word about bacteria?

• Some are good• Some are bad

• Turn to page 49A. Draw and label the bacteria cell. Color it as well. Use about ½ a page.

• Write this down and now to• Our last slide. . . . . .

When you are done with the bacteria cell drawing, label and coloring-- go to---------

• Page 43A and draw the virus particle there. Draw, label and color also using about ½ a page so you can see it well.

OK---get to work!!