Types of Microbes BACTERIA 1

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. 2

Cell Shapes The three basic shapes of bacteria are: Sphere shaped Spiral shaped bacteria Rod shaped bacteria 3

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. 4

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. 5

OBTAINING FOOD AND ENERGY All bacteria need the following to survive: A source of food A way of breaking down the food to release energy. 6

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: Some capture and use the Sun’s energy to make food Some use the energy from chemicals in their environment to make their food. 7

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. 8

Respiration (remember this?) Respiration = the process of breaking down food with the use of oxygen. Not all bacteria need oxygen. Some use FERMENTATION! Do you remember??? 9

REPRODUCTION Bacteria reproduce frequently when: They have plenty of food The right temperature Other conditions (water, the right chemicals) Under the best conditions (ideal) bacteria can reproduce as often as once every 20 minutes. 10

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. 11

Asexual Reproduction Binary Fission (a type of Asexual Reproduction) is just like CELL DIVISION, what we studied not too long ago. CELL DIVISION For Animal and Plant Cells BINARY FISSION (a type of Asexual Reproduction) For Bacteria PARENT 2 DAUGHTERS 12

Sexual Reproduction CONJUGATION = the process where 1 bacterium gives some of its DNA into another bacterium through a thread-like bridge 13

CONJUGATION THREAD-LIKE BRIDGE Bacteria 1 Bacteria 2 DNA BEFORE 14

CONJUGATION Bacteria 1 Bacteria 2 AFTER 15

Sexual Reproduction 1.Conjugation results in bacteria with new combinations of DNA. 16

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. 17

Endospore Formation Unfavorable conditions for bacteria growth are: No food No water A huge change in temperature 18

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 19

Endospore Formation

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. 21

THE ROLE OF BACTERIA IN NATURE GOOD THINGS BACTERIA DO: Make Oxygen Make Food Environmental recycling & clean-up Health & Medicine 22

THE ROLE OF BACTERIA IN NATURE BAD THINGS BACTERIA DO: Cause disease Spoil Food – waste money 23