Biology - Monera (Bacteria)

Microorganisms

very small living things

Distribution in Nature

• are found everywhere

• can survive in all habitats

Features of Bacteria

• are microscopic

• are single-celled

• have a cell wall

• do not have a nucleus or membrane-enclosed organelles (prokaryotic)

• have a single loop of DNA and a smaller loop called a plasmid

Cell Membrane

surrounds bacteria

Cell Wall

• is made of a complex mix of sugars and proteins

• prevents bacteria from swelling with water and bursting when they are in solutions that are less concentrated than their cytoplasm

Capsule

outside the cell wall, there may be further protection in the form of a semi-solid capsule or a more liquid slime layer

Plasmid

small DNA loop that can be found in the cytoplasm

contains the genes that are responsible for bacterial resistance to antibiotics

Bacterial Types

• round

• rod

• spiral

Pneumonia

example of round bacteria

Tuberculosis

example of rod shaped bacteria

Syphilis

example of spiral bacteria

Binary Fission

the method by which bacteria reproduce asexually

Process of Binary Fission

• DNA replicates

• DNA moves to both ends of the cell

• cell elongates

• cell divides in two, two identical cells are formed

Endospores

bacteria can withstand harsh and unfavourable conditions by producing…

Endospore Formation

• DNA replicates

• cytoplasm shrinks

Autotrophic

an organism that makes its own food

Green Sulfur Bacteria

example of autotrophic bacteria

Chemosynthesis

the production of food using energy released from chemical reactions

Nitrifying Bacteria

example of chemosynthetic bacteria

Heterotrophic

an organism takes in food made by other organisms

Salmonella

example of heterotrophic bacteria

Saprophytes

organisms that take in food from dead organic matter

Saprophytes and Parasites

types of heterotrophic nutrition used by bacteria

Parasites

organisms that take in food from a live host and usually cause harm

Factors Affecting the Growth of Bacteria

• pH

• temperature

• oxygen concentration

• water availability

• food availability

• presence of antibiotics

Pathogenic Bacteria

bacteria that cause disease

Antibiotics

chemicals produced by microorganisms that stop the growth of, or kill, other microorganisms without damaging human tissue

Antibiotic Resistance

can be caused by overuse/ misuse of antibiotics and by mutation in bacteria

Growth Phases

1. lag phase

2. log phase

3. stationary phase

4. decline phase

5. survival phase

Batch Culture

• fixed amount of nutrient added

• product removed at the end

• bacteria go through all stages of the growth curve

Continuous Flow Culture

• nutrients constantly added

• products constantly removed

• organisms maintained in one growth phase

Bioreactor

a vessel or container in which living cells or their products are used to make a product

Asepsis

the absence of pathogens

Sterility

the absence of all microorganisms