Types of Microbes BACTERIA

The Cell Structures

• Bacteria are PROKARYOTES = genetic material is not contained in a nucleus.

• DNA in a bacteria cell is found floating in the cytoplasm.

• A FLAGELLUM = a long whip-like structure that helps a cell to move. FLAGELLA = plural of FLAGELLUM

• A bacteria can have many flagella, one flagellum, or no flagella.

Cell ShapesThe three basic shapes of bacteria are:

Spiral shapedbacteria

Rod shapedbacteria

Sphere shapedbacteria

Cell Shapes

• The chemical make-up of the cell wall determines the shape of a bacterial cell. The shape helps Scientists identify the type of bacteria.

Cell Sizes

The size of bacteria vary greatly:

The largest bacteria = as big as a period at the end of a sentence.

Average bacteria = much smaller

They are usually measured in micrometers (μm) or millionths of a meter.

OBTAINING FOOD AND ENERGY

All bacteria need the following to survive:

1. A source of food

2. A way of breaking down the food to release energy.

Obtaining Food

• Some bacteria are AUTOTROPHS

• An AUTOTROPH = organisms that make their own food.

Q: Are humans autotrophs?

• The 2 ways autotrophic bacteria make food are:

1. Some capture and use the Sun’s energy to make food

2. Some use the energy from chemicals in their environment to make their food.

Obtaining Food

• A HETEROTROPH = organisms that cannot make their own food.

Q: Are humans heterotrophs?

• Heterotrophic bacteria must consume other organisms or the food that other organisms make.

Respiration (remember this?)

• Respiration = the process of breaking down food with the use of oxygen.

• All bacteria do not need oxygen. Some use FERMENTATION! Do you remember???

REPRODUCTION

Bacteria reproduce frequently when:

1. They have plenty of food

2. The right temperature

3. Other conditions (water, the right chemicals)

• Under the best conditions (ideal) bacteria can reproduce as often as once every 20 minutes.

Asexual Reproduction

• BINARY FISSION = the process of reproduction in bacteria where 1 cell divides to form 2 identical cells. It is a type of ASEXUAL REPRODUCTION = the reproductive process that involves only 1 parent and produces offspring that are identical to the parent.

Asexual Reproduction• Binary Fission (a type of Asexual

Reproduction) is just like CELL DIVISION, what we studied not too long ago.

CELL DIVISIONFor Animal and Plant Cells

BINARY FISSION(a type of Asexual Reproduction)For Bacteria

PARENT 2 DAUGHTERS

Sexual Reproduction

• SEXUAL REPRODUCTION = involves 2 parents who combine their DNA to produce a new organism. The new organism is different from both of the parents.

• CONJUGATION = the process where 1 bacterium gives some of its DNA into another bacterium through a thread-like bridge

CONJUGATION

Bacteria 1

Bacteria 2

DNA

THREAD-LIKEBRIDGE

BEFORE

CONJUGATION

Bacteria 1

Bacteria 2

AFTER

Sexual Reproduction

1.Conjugation results in bacteria with new combinations of DNA.

• Then, when the bacteria reproduce by Binary Fission, the resulting daughter bacteria have the new DNA in them.

Sexual Reproduction

2. Conjugation results in genetically different bacteria cells, not an increase in the number of bacteria cells.

• These NEW bacteria may be more fit to survive than the parent bacteria.

Endospore Formation

Unfavorable conditions for bacteria growth are:

1. No food

2. No water

3. A huge change in temperature

Endospore Formation

• An ENDOSPORE = a small, rounded, thick-walled resting cell that forms inside a bacterial cell. It contains the DNA and some cytoplasm

Endospore

Endospore Formation

• The formation of an Endospore allows the bacterium to stay alive in terrible conditions for years. Once the terrible conditions get better, the bacterium can begin to grow and reproduce again.

• Its kind of like HIBERNATION.

THE ROLE OF BACTERIA IN NATURE

GOOD THINGS BACTERIA DO:

1. Make Oxygen

2. Make Food

3. Environmental recycling & clean-up

4. Health & Medicine

THE ROLE OF BACTERIA IN NATURE

BAD THINGS BACTERIA DO:

1. Cause disease

2. Spoil Food – waste money