1. Bacteria

2. Learning Targets:
Describe the structure and function of a typical bacterial cell
Classify bacteria based on shape and arrangement
Describe how bacteria reproduce
Summarize the history and adaptations of bacteria
Evaluate the importance of bacteria
Identify diseases cause by bacteria

3. What are bacteria? Prokaryotes classified in 2 kingdoms unicellular
lack a nucleus and membrane-bound organelles
classified in 2 kingdoms
archaebacteria
eubacteria

4. What are archaebacteria?
live in extreme habitats
Methanogens = oxygen-free environments
Halophiles = very salty environments
Thermoacidophiles = hot, acidic environments

5. What are eubacteria? Heterotrophs Found everywhere
parasites obtain nutrients from living organisms
saprophytes feed on dead organisms/organic waste

6. Autotrophic eubacteria
photosynthetic autotrophs
Obtain energy from light
Make own food
Cyanobacteria

7. Chemosynthetic autotrophs
break down & release the energy of inorganic compounds containing S & N to make organic molecules that are their food

8. Anatomy of a bacterium?
Cell wall gives shape & prevents osmosis from bursting the cell
Capsule surrounds cell wall
Circular chromosome (single DNA molecule) not enclosed in a nucleus contains most of the genes
Few genes are located in a small circular plasmid
Plasma (cell) membrane regulates what enters & leaves the cell
Hair-like pilus helps a bacterium stick to a surface
helps exchange DNA
Whip-like flagellum enable them to move

9. Flagellum
Clip 1
Clip 2

10. Bacterial culture techniques
             
             
Carefully & thoroughly swab selected surface
Transfer bacteria from broth culture to nutrient agar plate by touching swab to agar surface in a single spot
Isolate bacterial colonies by streaking the plate, being careful not to tear agar
Incubate plate

11. Pure culture
population of bacterial cells growing in the absence of other types
streak plate technique is used to spread millions of cells so that some are deposited a distance from all others
these cells grow & reproduce, forming an isolated colony (represents a pure culture)

12. How can bacteria be identified?
Gram staining checks for differences in the structure of their cell walls
gram-positive bacterial cells turn purple
gram-negative cells turn pink
doctors know which antibiotics to use based on the results

13. Penicillin inhibits Stapylococcus
Antibiotics
Bacteria live in hypotonic environments
higher concentration of water outside than inside cell
water is always trying to enter cell
A bacterial cell remains intact & doesn’t burst open as long as its cell wall is intact
scientists used this need to develop antibiotics
Penicillin inhibits Stapylococcus

14. Disc diffusion
antibiotic discs release antibiotic into surrounding medium
zone of growth inhibition
Area of no bacterial growth
around the disc will occur if the bacteria are susceptible to the antibiotic

15. Antibiotic resistant bacteria

16. Shapes of bacteria another way to identify bacteria sphere = coccus
rod = bacillus
spiral = spirillium

17. Growth pattern of bacteria
also used to identify bacteria
pairs = diplo-
grape clusters = staphylo-
long chains = strepto-

18. Draw the following… Diplococcus meningitidis causes meningitis
Streptococcus pneumoniae causes pneumonia
Staphylococcus aureus causes toxic shock syndrome and boils

19. 2 kinds of Reproduction

20. How do bacteria asexually reproduce?
Binary fission
makes a copy of its chromosome
cell grows larger
chromosomes move to opposite ends of the cell
a wall begins to form in the middle
2 new cells are genetically identical

21. Binary fission video clip

22. How do bacteria sexually reproduce?
Conjugation
pilus = bridge-like structure that one bacterium uses to connect to another
1st bacterium transfers all or part of its chromosome to the second through the pilus
2nd bacterium has a mix of genetic material & reproduces by binary fission
produces bacteria with a whole new genetic combination

23. Conjugation video clip

24. Diversity of metabolism
Obligate aerobes require oxygen for respiration
Mycobacterium tuberculosis causes tuberculosis
Obligate anaerobes are killed by oxygen
Treponema pallidum causes syphilis
Clostridium botulinum causes botulism
Mycobacterium tuberculosis
Clostridium botulinum

25. Facultative anaerobes
Bacteria that prefer an aerobic condition
Can make ATP with no oxygen if put into that situation
Ex’s
Staphylococcus (g+)
E. coli (g-)
Listeria (rare food borne illness-25% lethal)
Corynebacteria- skin flora

26. Which tube flourishes in O2?

27. Whats up?

28. A survival mechanism Endospore
tiny structure that contains bacterium’s DNA & small amount of cytoplasm
encased by tough outer covering that resists drying out, temperature extremes, & harsh chemicals
bacterium rests & doesn’t reproduce

29. The importance of bacteria
Disease-causing bacteria are few in number compared with the number of harmless & beneficial bacteria on Earth
help to fertilize fields
help to recycle nutrients
help to produce foods & medicine

30. Food Safety

31. Nitrogen fixation
All organisms need nitrogen, yet few can directly use it from air
nitrogen fixation – process of converting nitrogen gas into ammonia
other bacteria convert ammonia into nitrate & nitrite which plants can use
Animation
Rhizobium on plant nodules convert nitrogen gas into ammonia

32. Recycling of nutrients
Life could not exist if decomposing bacteria didn’t break down organic materials in dead organisms and wastes
returns nutrients to the environment

33. Food and medicines
During respiration, different bacteria produce diverse products which have distinctive flavors & aromas
vinegar
yogurt & cheeses
sauerkraut
sour cream
Some bacteria produce important antibiotics that destroy other types of bacteria
streptomycin
erythromycin
bacitracin
neomycin

34. What diseases do bacteria cause?
Diseases Caused by Bacteria
Disease
Transmission
Symptoms
Treatment
Strep throat
inhale/ingest
fever, sore throat, swollen glands
antibiotic
Tuberculosis
inhale
fatigue, fever, night sweat, cough, chest pain
Tetanus
puncture wound
stiff jaw, muscle spasms, paralysis
antibiotic, antitoxin
Lyme disease
tick bite
rash, chills, body aches, joint swelling
Cavities
bacteria
toothache
fillings
Diphtheria
inhale/contact
sore throat, fever, heart/breathing failure
vaccine, antibiotics

35. Bacteria and Disease
50% of all diseases are thought to be caused from bacteria
In 1900, tuberculosis and pneumonia were the two most common diseases
Factors that increased life expectancy:
Less poverty, better health systems, increased water and sewage systems, increased nutrition, better medical care

36. Are there bacteria on cell phones?

37. Controlling Bacteria Cooking Foods Referigeration/freezing
Drying foods
Pickling