1

BACTERIA

2

Characteristics of Bacteria

Did you know that billions of tiny organisms too small to be seen surround you? These organisms, called bacteria are microscopic prokaryotes. You might recall that a prokaryote is a unicellular organism that does not have a nucleus or other membrane-bound organelles.

Bacteria live in almost every habitat on Earth, including the air, glaciers, the ocean floor and in soil. A teaspoon of soil can contain between 100 million and 1 billion bacteria. Bacteria also live in or on almost every organism, both living and dead. Hundreds of species of bacteria live on your skin. In face, your body contains more bacterial cells than human cells! The bacteria in your body outnumber human cells by 10 to 1!

From textbook page 253

3

BACTERIA Bacteria like a warm, dark, and moist environments.

They are found almost everywhere:

-water -air

-soil -food

-skin

-inside the body

-on most objects

How do bacteria get in the body?• Air

– Droplets containing microbes fly into the air when people sneeze or cough. The microbes they contain get into other people if breathed in.

– Chicken pox, colds, flu, measles and tuberculosis are spread like this.• Animals

– Animals may carry harmful microbes. The microbes can get into a person who is scratched or bitten by such an animal. Malaria is a tropical disease spread by a tiny fly called a mosquito.

• Food– Food can have harmful microbes in and on it. The microbes get into the body when the food is

eaten, causing food poisoning. Thorough cooking kills most microbes, but they can survive under-cooking. Careless handling of food increases the risk from harmful microbes.

• Touch– Microbes can be passed from one person to another when people touch each other, or when

they touch something an infected person has handled. Athlete's foot is spread like this.– Bacteria on the skin can be killed by antiseptics, and bacteria on surfaces can be killed by

disinfectants. Washing your hands reduces the chance of spreading microbes.• Water

– Water can have harmful microbes in it. The microbes get into the body when the water is swallowed. Cholera is a disease caused by a bacterium that spreads like this. Thorough boiling or adding chlorine to the water can reduce the chance of spreading microbes in this way

4

5

3 Shapes of 3 Shapes of BacteriaBacteria

Rod-shaped

Spiral-shaped

Round or Sphere-shaped

6

7 Major Structures of a Bacteria Cell

•Capsule

•Cell wall

•Ribosomes

•Nucleoid

•Flagella

•Pilli

•Cytoplasm

7

Capsule

7 Major Structures of a Bacteria Cell

keeps the cell from drying out and helps it stick to food or other cells

8

Cell wall

7 Major Structures of a Bacteria Cell

Thick outer covering that maintains the overall shape of the bacterial cell

9

Ribosomes

7 Major Structures of a Bacteria Cell

cell part where proteins are made

Ribosomes give the cytoplasm of bacteria a granular appearance in electron micrographs

10

Nucleoid

7 Major Structures of a Bacteria Cell

a ring made up of DNA

11

Flagella

7 Major Structures of a Bacteria Cell

a whip-like tail that some bacteria have for locomotion

12

Pilli

7 Major Structures of a Bacteria Cell

hollow hair-like structures made of protein

allows bacteria to attach to other cells.

Pilli-singular Pillus-plural

13

Cytoplasm

7 Major Structures of a Bacteria Cell

clear jelly-like material that makes up most of the cell

14

Fission- Type of asexual reproduction. Cell division that forms two genetically identical cells.

Reproduction of Reproduction of BacteriaBacteria

Asexual reproduction- reproduction of a living thing from only one parent

15

                                                                           1

                                                                           1

                                                                           1

                                                                           1

                                                                           1

Human tooth with accumulation of bacterial plaque (smooth areas) and

calcified tartar (rough areas)

Harmful Bacteria

16

Harmful Bacteria

Bacteria can also cause infections such as tuberculosis, pneumonia, meningitis and strep throat.

Eating food that is contaminated by some bacteria can cause food poisoning.

17

Helpful Bacteria•Decomposers help recycle nutrients into

the soil for other organisms to grow

•Bacteria grow in the stomach of a cow to break down grass and hay

•Most are used to make antibiotics

•Some bacteria help make insulin

•Used to make industrial chemicals

18

                                                                           1

                                                                           1

                                                                           1

                                                                           1

                                                                           1

E.coli on small intestines

Helpful Bacteria

19

•Used to treat sewage          

Organic waste is consumed by the bacteria, used as nutrients by the bacteria, and is no longer present to produce odors, sludge, pollution, or unsightly mess.

•foods like yogurt, cottage & Swiss cheese, sour cream, buttermilk are made from bacteria that grows in milk

Helpful Bacteria

20

BLUE-GREEN BACTERIAAutotrophs – make their own

food through photosynthesis

commonly grow on water and surfaces that stay wet…such as rivers, creeks and dams

larger than most bacterial cells

Some live in salt water, snow, and acid water of hot springs

food source for animals that live in the water

21

BLUE-GREEN BACTERIA

Blooms- occur when the bacteria multiplies in great numbers and form scum on the top of the water

can be toxic to humans and animals

22

                                                                           1

                                                                           1

                                                                           1

                                                                           1

                                                                           1