What are the two kingdoms that contain bacteria?

Archaebacteria “The extremists”

Eubacteria “Found everywhere”

• A bacterial cell is a very small prokaryotic cell.

• Although tiny, a bacterial cell possesses all the characteristics of life.

Bacteria

Ribosomes (makes proteins)

Capsule (outer-most layer) not all bacteria have this

Cell Wall Middle layer

Plasma Membrane Inner-most

layer Flagella (helps it move) not all bacteria have this

• A bacterial cell remains intact (together) as long as its cell wall is intact.

If the cell wall is damaged, water will

enter the cell by osmosis, causing the

cell to burst.

• Scientists used a bacteria’s need for an intact cell wall to develop a weapon against bacteria that cause

disease.

Bacterium Structure

• In 1928, Sir Alexander Fleming accidentally discovered penicillin, the first antibiotic—a substance

that destroys bacteria.

Antibiotics

He had been looking at bacteria under the microscope. He left the dirty slides in the sink, and a mold began to grow on them. He later noticed that the mold was killing the

bacteria.

• Later, biologists discovered that penicillin can destroy the cell walls of bacteria.

• When bacteria are put in penicillin, holes develop in their cell walls, water enters their cells, and they

rupture and die.

Antibiotics

AntibioticsUnfortunately, antibiotics kill both good and bad bacteria.

You have good bacteria that live in your intestine that help you digest food.

Eating foods that contain these good bacteria while you are taking an antibiotic can help keep and/or

replenish your body’s supply…yes, the above foods contain LIVING good bacteria.

• One trait that helps classify bacteria is how they react to Gram stain.

• Gram staining is a technique that stains bacteria a certain color, which lets doctors/scientists know what kind of cell wall the bacteria possess. This helps doctors decide which antibiotics to use.

Identifying Bacteria

GRAM POSITIVE GRAM NEGATIVEStain purple- thicker cell wall Stain pink- thinner cell wall

• Diplo–is a prefix that refers to bacteria that pair up.

• The prefix Staphylo–describes an arrangement of cells that

resemble grapes.

• Strepto–is a prefix that refers to an arrangement of chains of cells.

Identifying BacteriaBacterial cells often grow in characteristic patterns that provide another way of categorizing them.

• The three most common shapes are:

Spheres, called “coccus”

Rods, called “bacillus”

Spirals, called “spirillum”

Bacterium Shapes

1. The above bacteria stained a dark purple. What does that tell you about this bacteria?

Strong/Thick cell wall

2. The above bacteria grows in chains and the cells are round. What is the name of this bacteria?

Strepto-coccus

• Bacteria reproduce asexually by a process known as binary fission.

Bacteria Reproduction

•Basically, it is mitosis for a bacterial cell. The end result is

two identical bacterias.

Bacteria Reproduction

• Under ideal conditions, some bacteria can reproduce every 20 minutes, producing enormous numbers of bacteria quickly.

• Some bacteria communicate in a process called conjugation.

• During conjugation, one bacterium transfers all or part of its chromosome to another bacteria through or on a

bridge-like structure called a pilus that connects the two cells.

Bacteria Reproduction

• Some bacteria, when faced with unfavorable environmental conditions, produce a tiny

“escape pod” called an endospore.

• An endospore is a tiny structure that contains a

bacterium’s DNA and a small amount of its cytoplasm, encased by a tough outer

covering that resists drying out, temperature extremes, and harsh

chemicals.

Survival Mechanism

• As an endospore, the bacterium rests and does not reproduce.

Survival Mechanism

• Endospores can survive a temperature of 100˚C, which is the boiling point of water.

GOOD BACTERIA

IN YOUR BODY• Trillions of “good” bacteria live in your body. Most are found in your intestinal

tract.

Lactobacillus acidophilus

• It protects intestines, helps aid in digestion, helps build immunity to food allergies, and lowers

blood cholesterol.

Write what is in blue

and underlined

• Some foods that you eat—mellow Swiss cheese, crispy pickles, vinegar, sauerkraut,

and tangy yogurt—would not exist without bacteria.

GOOD BACTERIA

Makes Some Foods and Medicines

• In addition to food, some bacteria produce important medicines.

GOOD BACTERIA

Makes Some Foods and Medicines

• Remember, bacteria help convert nitrogen in the soil so that plant’s can use it

and grow better!

GOOD BACTERIA

Help with Farming

GOOD BACTERIA

Recycle Nutrients

Life could not exist if bacteria did not break down decomposing organisms and return the

nutrients to the environment.

We will use an agar dish to grow bacteria.

Agar is a jelly-like polysaccharide where certain cells can grow. It’s a “food” for the bacteria.

Form groups of two or three