Bacteria

Prokaryotic Structures Capsule: (not shown) sometimes surrounds pathogenic bacteria as an added layer of protection.

a. cell wall: b. cell (plasma) membrane: c. nucleoid: d. ribosome: e. cytoplasm f. flagellum: g. pili:

Prokaryotic Characteristics  Prokaryotes: Lack a nucleus DNA clustered in cytoplasm  Simpler structure than other cells: Lack membrane bound organelles,  Very tiny: smallest cells on the planet

Prokaryotic Shapes

Prokaryotic Motility Bacteria move in different ways, but they take the path of least resistance when moving through a medium, like a culture or the human body!

Binary Fission  Bacteria Reproduction Binary Fission: A type of asexual reproduction common among prokaryotes wherein a cell divides to produce two cells

Prokaryotic Reproduction

E.coli  E.Coli can reproduce every 20 minutes under optimum conditions  How many bacteria would there be after 24 hours?

Why doesn’t bacteria take over?  The primary reason may be that conditions are rarely optimum.  Scientists who study bacteria try to create the optimum environment in the lab: culture medium with the necessary energy source, nutrients, pH, and temperature, in which bacteria grow predictably

Rate of Prokaryotic Reproduction  Lag phase: Reproduction is just beginning  Log phase: Reproduction is occurring at an exponential rate (the population doubles approximately every 20 minutes)  Stationary phase: Environmental conditions cannot support further exponential growth. Population is stable.  Death phase: Resources have been depleted. Population dies off. How is this similar to a human growth curve?

Genetic Recombination (Honors) Transformation Fragment of DNA from environment combines with bacteria DNA Transduction Virus injects fragment of DNA from former host Conjugation Two bacteria connect via pili and transfer plasmid DNA

Prokaryotic Metabolism: Releasing energy from food Chemoheterotroph Use chemicals from other organisms as source of energy or food. Ex: Streptococcus mutans Photoautotroph Use light as source of energy to make food. Ex: Cyanobacteria Chemoautotroph Use chemicals as source of energy to make food. Ex: Archaeoglobus

Prokaryotic Metabolism: Releasing energy from food Obligate Aerobes Must have oxygen to release energy from food. Obligate Anaerobes Oxygen must not be present to release energy from food. Facultative Anaerobes Can release energy in food with or without oxygen So, what type of bacteria will die in the presence of oxygen? What type of bacteria can survive in either condition? What type of bacteria will die if there is no oxygen?

Disease Causing Prokaryotes Toxins: chemicals produced by prokaryotes that destroy human tissue. Or, they may be using our cells as their source of energy (food).

Conjugation: acquiring new genes Some bacteria can transfer DNA to other bacteria through their pili.

Benefits of Prokaryotes:

Benefits of Prokaryotes  Regulates bowel movements  Helps in the formation of vitamins  Enhances the immune system  Regulates hormone levels  Controls cholesterol levels

Controlling Prokaryotes

 Dehumidifiers/Dehydrators  Freezers  Pasteurization  Sterilization  Disinfectants  Antibiotics

Superbacteria: resistant bacteria Evolution in Action The misuse and overuse of antibiotics has lead to the evolution of resistant bacteria. MRSA, TB, gonorrhea, malaria & typhoid fever have all evolved because of antibiotic misuse. ducators/lessons/lesson6/act1.html

If antibiotics are not taken properly, some resistant bacteria remain alive. These surviving bacteria reproduce and pass on their genes, leading to a new population of bacteria that will not die with current antibiotics. What can we do to slowdown this process? Don't use antibiotics when you don't have to. In particular don't give antibiotics for non-bacterial conditions. Be sure to complete the course of treatment when given antibiotics.

Prokaryotes are classified into two domains:

Bacteria  Largest and most diverse kingdom  Cell wall peptidoglycan (carbohydrate)  Tiny fraction of these can cause disease  Found wherever humans are found Soil Human intestines Human skin

Archaea (Ancient)  Genetically related to eukaryotes—could they be ancestors?  Lack peptidoglycan in cell wall  Different lipids in cell membrane  May live in EXTREME environments Methanogens (no oxygen) Halophiles (salt lovers) Thermophiles (heat lovers) Other planets ?

Venn Diagram  You and your partner will create a Giant Venn Diagram to show the similarities and differences between Prokaryotes and Viruses. Use illustrations and descriptions to make it visually appealing.

Biotechnology and Prokaryotes  Food Production Food Production  iotech%20works.htm iotech%20works.htm