1. Bacteria Earth’s oldest life forms (PROKARYOTES) Earth’s oldest life forms (PROKARYOTES) – between 3.5 and 3.8 billion years old Most abundant life form – up to 2.5 billion individual bacteria in 1 gram of fertile soil Most abundant life form – up to 2.5 billion individual bacteria in 1 gram of fertile soil Very adaptable – found in all of Earth’s Very adaptable – found in all of Earth’s ecosystems ecosystems

2. Bacteria Characteristics Unicellular Unicellular Circular DNA Circular DNA No organelles No organelles 1/10 th the size of eukaryotic cells 1/10 th the size of eukaryotic cells Flagella-long hair-like structure used for movement Flagella-long hair-like structure used for movement Reproduce asexually –Binary Fission Reproduce asexually –Binary Fission

3. Bacterial Shapes 3 main shapes 3 main shapes - coccus – sphere - coccus – sphere - bacillus – rods - bacillus – rods - spirillum - spiral - spirillum - spiral

4. Bacterial Characteristics Metabolic diversity – Bacteria can produce energy in a variety of circumstances Metabolic diversity – Bacteria can produce energy in a variety of circumstances autotroph – (self-feeding) – some bacteria can produce their own food - some use photosynthesis – get energy from light - some use photosynthesis – get energy from light - some use chemosynthesis – get energy from - some use chemosynthesis – get energy from chemicals chemicals Heterotroph - (other feeding) – many bacteria Heterotroph - (other feeding) – many bacteria are unable to produce their own food and are required to eat other things are unable to produce their own food and are required to eat other things

5. Bacterial Characteristics: Metabolic diversity continued obligate aerobe – like us these bacteria need oxygen obligate anaerobe - these bacteria need to be in an oxygen free environment – human gut facultative anaerobe – these bacteria can live in either an oxygen or oxygen free environment

6. Bacterial Structure Cell Wall Cell Membrane Pilus chromosome plasmid flagellum nucleoid ribosome cytoplasm capsule

7. Bacterial Structure: Cell Wall Made of peptidoglycan – a combination of protein and polysaccharides Made of peptidoglycan – a combination of protein and polysaccharides Some bacteria called Gram negative bacteria have an additional layer of membrane that contains lipopolysaccharide Some bacteria called Gram negative bacteria have an additional layer of membrane that contains lipopolysaccharide - this extra layer inhibits the uptake of antibiotics – protecting - this extra layer inhibits the uptake of antibiotics – protecting the bacteria the bacteria cell membrane cell wall cell membrane Outer membrane lipopolysaccharide cell wall

8. Gram + vs. Gram - Absorb stain appear purple Don’t absorb stain appear pink The type of cell wall is used by doctors to help diagnose disease The bacteria are stained with a special stain called Gram stain Bacteria without the extra membrane, appear purple. These are Gram positive (Gram +) bacteria Bacteria with the extra membrane appear pink. These are Gram negative ( Gram -) bacteria

9. Bacterial Structure continued Pili – hairlike structures usually found Pili – hairlike structures usually found in Gram neg. bacteria. Help the bacteria stick to surfaces. in Gram neg. bacteria. Help the bacteria stick to surfaces. Also forms conjugation bridge Chromosome – a single loop of DNA Chromosome – a single loop of DNA that is folded on itself that is folded on itself - controls the cell’s function - controls the cell’s function Nucleoid – the region of the cytoplasm Nucleoid – the region of the cytoplasm where the DNA is found where the DNA is found Plasmid – an accessory loop of DNA – small contains only a few genes - can be responsible for: conjugation, antibiotic resistance, unique metabolic properties – like the ability to use hydrocarbons Plasmid – an accessory loop of DNA – small contains only a few genes - can be responsible for: conjugation, antibiotic resistance, unique metabolic properties – like the ability to use hydrocarbons Capsule – found outside some bacteria stores nutrients and protects the bacteria from changing environmental conditions Capsule – found outside some bacteria stores nutrients and protects the bacteria from changing environmental conditions

10. Reproduction - Binary Fission Bacterial cells undergoing binary fission Bacterial cells undergoing binary fission

11. Reproduction - Binary Fission Asexual reproduction Asexual reproduction - offspring are genetically - offspring are genetically identical to parent – no identical to parent – no new genetic combinations new genetic combinations - under ideal conditions - under ideal conditions can occur every 20 min can occur every 20 min - creates large numbers - creates large numbers of bacteria in a short of bacteria in a short time time

12. Each spot represents Each spot represents a single bacterial a single bacterial cell that reproduced cell that reproduced by binary fission to by binary fission to produce millions of produce millions of genetically identical genetically identical cells. cells. Genetically identical, Genetically identical, good or bad? good or bad?

13. Exchanging Genetic Information Bacterial cells need to be able to exchange genetic information Bacterial cells need to be able to exchange genetic information - creates new genetic combinations which increases the ability of the bacteria to survive - creates new genetic combinations which increases the ability of the bacteria to survive Bacteria have 3 methods for exchanging DNA Bacteria have 3 methods for exchanging DNA -Transduction – viruses carry DNA from one bacterial cell to another -Transduction – viruses carry DNA from one bacterial cell to another -Transformation – bacteria can absorb “naked” DNA released by dead bacteria from the environment -Transformation – bacteria can absorb “naked” DNA released by dead bacteria from the environment - Conjugation – two bacteria join at a conjugation bridge, one bacteria passes on a copy of its plasmid or chromosome - Conjugation – two bacteria join at a conjugation bridge, one bacteria passes on a copy of its plasmid or chromosome

14. Exchanging Genetic Information

15. Transduction – DNA is carried from one bacteria to another by a virus

16. Transformation: Bacteria absorb “naked” DNA from the environment

17. Conjugation

18. Conjugation- one cell passes a copy of its plasmid or chromosome to another Donor Cell Recipient Cell A special pilus forms a connection called a conjugation bridge between 2 bacterial cells PlasmidConjugation bridge The donor cell copies its plasmid or chromosome and passes the copy through the conjugation bridge Cells separate

19. Bacteria Play Important Roles in Ecosystems Decomposers Decomposers – recycle dead organisms releasing their nutrients back to the environment for use by other organisms – SPONCH – recycle dead organisms releasing their nutrients back to the environment for use by other organisms – SPONCH Without decomposers, Without decomposers, the elements on earth the elements on earth would have remained would have remained locked up in dead organisms and life would have ceased locked up in dead organisms and life would have ceased

20. Bacterial Roles: Nitrogen Fixation some bacteria contain enzymes which allow them to convert (or fix) nitrogen from the air into a useable form some bacteria contain enzymes which allow them to convert (or fix) nitrogen from the air into a useable form - they are nitrogen fixing bacteria - they are nitrogen fixing bacteria - Why do living things use nitrogen?

21. Bacterial Roles: Producers In some ecosystems In some ecosystems chemosynthetic and chemosynthetic and photosynthetic bacteria photosynthetic bacteria serve as the basis of serve as the basis of the food chain the food chain – chemosynthetic bacteria in deep ocean vents convert hydrogen sulfide (H 2 S) gas into energy - cyanobacteria are photosynthetic bacteria - cyanobacteria are photosynthetic bacteria which act as producers in many aquatic which act as producers in many aquatic ecosystems ecosystems

22. Bacterial Roles: Symbiotic Bacteria Many bacteria live in or on other organisms (including humans) and aid their host - some live in the gut of herbivores helping to digest cellulose - some live in the gut of herbivores helping to digest cellulose - bacteria in the gut of humans - bacteria in the gut of humans aid digestion and produce vitamins - bacteria on skin and in body - bacteria on skin and in body openings help prevent infection by harmful organisms

23. Bacterial Roles: Pathogenic Bacteria Pathogens are organisms that cause disease Pathogens are organisms that cause disease - only a small portion of bacteria are pathogens - most bacteria diseases are caused by toxins released by the bacteria released by the bacteria - these toxins: - these toxins: - poison cells and damage tissue - poison cells and damage tissue - interfere with cell signaling - interfere with cell signaling - over-stimulate cells causing them to malfunction - over-stimulate cells causing them to malfunction

24. Antibiotics Antibiotics are chemicals which either kill bacteria or prevent their growth and reproduction Antibiotics are chemicals which either kill bacteria or prevent their growth and reproduction Bacteria and other microbes produce antibiotics to reduce competition from other organisms Bacteria and other microbes produce antibiotics to reduce competition from other organisms Penicillin was the first to be use to fight disease Penicillin was the first to be use to fight disease - discovered accidently by Alexander Fleming in 1928 The discovery of antibiotics The discovery of antibiotics revolutionized the treatment revolutionized the treatment of disease of disease

25. Antibiotic Action Antibiotics effect bacteria, but not eukaryotic cells Antibiotics effect bacteria, but not eukaryotic cells Antibiotics attack bacteria in 5 ways Antibiotics attack bacteria in 5 ways - some damage the cell walls or prevent new cell wall from forming - some damage the cell membrane - some damage the cell membrane - some prevent protein synthesis - some prevent protein synthesis - some prevent DNA from being copied - some prevent DNA from being copied - some interfere with bacterial metabolism - some interfere with bacterial metabolism

26. Antibiotic Action Agar plates were seeded with Pseudomonas aeruginosa and Staphylococcus aureus. Agar plates were seeded with Pseudomonas aeruginosa and Staphylococcus aureus. Four antibiotic disks were dispensed on each plate. Four antibiotic disks were dispensed on each plate. The disks contained 30 µg of tetracycline (top left), 30 µg of vancomycin (top right), 10 µg of ampicillin (bottom left), and 30 µg of chloramphenicol (bottom right). The disks contained 30 µg of tetracycline (top left), 30 µg of vancomycin (top right), 10 µg of ampicillin (bottom left), and 30 µg of chloramphenicol (bottom right).

27. Antibiotic Action Both plates were incubated at 30°C overnight. The diameter of each zone was measured in millimeters and evaluated for susceptibility or resistance using the comparative standard method. Antibiotic susceptibility was compared between the two strains of bacteria. Both plates were incubated at 30°C overnight. The diameter of each zone was measured in millimeters and evaluated for susceptibility or resistance using the comparative standard method. Antibiotic susceptibility was compared between the two strains of bacteria.

28. 30 µg of tetracycline 30 µg of vancomycin 10 µg of ampicillin 30 µg of chloramphenicol

29. 10 µg of ampicillin 30 µg of tetracycline 30 µg of chloramphenicol 30 µg of vancomycin

30. Antibiotic Resistance Some bacteria have developed a resistance to the effect Some bacteria have developed a resistance to the effect of some antibiotics of some antibiotics - the number of resistant bacteria is growing - the number of resistant bacteria is growing The problem is increased by overuse and misuse of antibiotics The problem is increased by overuse and misuse of antibiotics - use of antibiotics to treat viral infections – antibiotics don’t effect viruses - use of antibiotics to treat viral infections – antibiotics don’t effect viruses - the use of antibiotics in livestock (cattle, chickens, pigs) - the use of antibiotics in livestock (cattle, chickens, pigs) antibiotics show up in the meat and milk antibiotics show up in the meat and milk - people take the antibiotics until they feel better, but stop before all of the bacteria are destroyed - people take the antibiotics until they feel better, but stop before all of the bacteria are destroyed - this kills the most susceptible bacteria, but leaves the more resistant bacteria - this kills the most susceptible bacteria, but leaves the more resistant bacteria

31. Black Plague-Yersinia pestis

32. Pseudomonas aeruginosa infection Pseudomonas aeruginosa infection

33. Staphylococcus aureus infection