1. Ch. 18—Prokaryotes

2. All organisms in domains Archaea and Bacteria are considered prokaryotic.
What does it mean to be prokaryotic?
Do NOT have a nucleus.
Do NOT have membrane bound organelles (like mitochondria, ER, Golgi)
But they DO have ribosomes, DNA, cell membrane, cytoplasm/cytoskeleton

3. 18.4 Bacteria and Archaea Prokaryotes are widespread on Earth
Prokaryotes are the most widespread and abundant organisms on Earth.
for perspective:
humans (eukaryotes) are one species with 7 billion individuals
a gram of soil may contain 10,000 types of bacteria (prokaryotes) and 5 billion bacterial cells

4. Prokaryotes are widespread on Earth.
microscopic
one of the earliest life forms
found inside your body, inside volcanoes, on your pencil- EVERYWHERE (ubiquitous)!
prokaryotes can be grouped based on their need for oxygen
aerobic- need oxygen
anaerobic- do not need oxygen

5. The domain Bacteria and Archaea are structurally similar but have different molecular characteristics.
There are two domains that contain prokaryotes: Bacteria and Archaea
domain Bacteria is more diverse and widespread than domain Archaea
domain Archaea is more likely to be found in extreme environments than domain Bacteria

6. Kingdom: Archaea (Archaebacteria) Domain: Bacteria
Domain: Archaea
Kingdom: Archaea (Archaebacteria)
Domain: Bacteria
Kingdom: Bacteria (Eubacteria)
“ancient”
most heterotrophs (some autotrophs)
cells walls WITHOUT peptidoglycan; unique lipids
found in harsh/extreme environments
Examples:
methanogens- don’t need oxygen (anaerobic), make methane gas
thermophiles- very hot water
halophiles- very salty conditions, 10x saltier than ocean water
most diverse
most are heterotrophs (some autotrophs)
cell walls WITH peptidoglycan
found everywhere
Examples:
Escherichia coli
Clostridium botulinum
Bacillus anthracis

7. Archaea in San Francisco Bay area – extremely high salinity.
What kind of archaeans are these?
halophiles

8. Structural Comparisons of Bacteria and Archaea
both are small, single-celled organisms
both have
cell walls
plasma/cell membranes
DNA (chromosome) is in a circle in the cytoplasm (not found in a nucleus because they don’t have a nucleus)
ribosomes

9. Structural Comparisons of Bacteria and Archaea
both may have plasmids
plasmid – small piece of genetic material (DNA) that can replicate separately from the prokaryote’s main chromosome

10. Structural Comparisons of Bacteria and Archaea
both are generally motile – able to move on their own
flagellum – whiplike structure outside of a cell used for movement
attached to plasma membrane and cell wall

11. Structural Comparisons of Bacteria and Archaea
both often contain pili
pili – thin, short, numerous projections that help prokaryotes stick (attach) to surfaces and each other; pili also function in sexual reproduction in bacteria

12. BACTERIA DO NOT HAVE CILIA!!!!

13. Structural Comparisons of Bacteria and Archaea
both have multiple shapes
Archaea come in many shapes
Bacteria have 3 basic shapes:
bacilli(us) – rod-shaped
spirilla(um) or spirochete – spiral-shaped
cocci(us) – spherical (round)

14. Bacterial Shapes
bacillus
coccus
spirillum

15. Structural Comparisons of Bacteria and Archaea
Label:
coccus
bacillus
spirillum

16. Structural Comparisons of Bacteria and Archaea
Bacteria have 2 basic arrangements
strepto– strips or chains
staphylo- clusters

17. Structural Comparisons of Bacteria and Archaea
If your doctor said you had Strep throat (“Streptococcus”), what would shape and arrangement of the bacteria look like under the microscope?
If your doctor said you had a staph infection (“Staphylococcus”), what would shape and arrangement of the bacteria look like under the microscope?
Answer:
chains of circles
Draw:
Answer:
clusters of circles
Draw:

18. Bacteria Structure and Function
Fill in the missing structural terms in your notes in the Structure and Function Chart.

19. Bacteria Structure and Function
Fill in the terms from the chart on the diagram below. Then, number these structures (1,2,3) starting with the outside of the cell and moving to the inside: cell wall, capsule, plasma membrane
plasmid
DNA
ribosome
flagella
Capsule - 1
cell wall - 2
plasma membrane - 3
pili

20. Bacteria have various strategies for survival.
Reproductive strategies
binary fission
conjugation
and
Strategies for surviving harsh conditions

21. Gene Exchange in Prokaryotes
binary fission – prokaryotic asexual reproduction
Bacteria divides in half producing identical offspring.
chromosome copies itself (like in DNA replication)
the cell grows to double its size
plasma membrane grows inward and divides the cell into two, each with a full set of the original cell’s genes.

22. binary fission – prokaryotic asexual reproduction

23. Gene Exchange in Prokaryotes
conjugation – exchange of genetic material through a hollow bridge of pili connecting 2 or more cells

24. Surviving Harsh Conditions
endospore – specialized cell with a thick, protective wall formed for survival during unfavorable conditions
bacterium copies its chromosome
produces a wall around the copy
thick wall withstands drying out (desiccation), temperature change, and disinfectants
can last for centuries
Examples: Bacillus anthracis (causes anthrax);
Clostridium botulinum (causes botulism—a form of food poisoning)

25. 18.5 Beneficial Roles of Prokaryotes
Prokaryotes provide nutrients to humans and other animals.
prokaryotes are key in animal digestive systems in balanced communities
mutualistic symbionts
host benefits
make vitamins and other compounds
keep away harmful microbes by filling niches they might occupy (out-competing them)
bacteria benefits
break down food while getting a place to live
place to live has stable pH and temperature

26. Develop mutualistic relationships with other organisms: Ex
Develop mutualistic relationships with other organisms: Ex. the fish provides the bioluminescent bacteria under its eye with organic materials, the fish uses its living flashlight to lure prey and to signal mates. potential mates.

27. Prokaryotes provide nutrients to humans and other animals.
many foods humans eat are fermented by bacteria
ferment – chemically break down
yogurt
pickles
cheese
sauerkraut
soy sauce
vinegar

28. Prokaryotes play important roles in ecosystems.
* PRINCIPLE DECOMPOSERS (along with fungi)
recyclers of carbon, nitrogen, hydrogen, and sulfur through ecosystems
photosynthesizers – cyanobacteria produce oxygen; were key to increasing the oxygen content of early earth

29. Cyanobacteria

30. Prokaryotes play important roles in ecosystems.
- nitrogen fixers - fix nitrogen; convert atmospheric nitrogen into ammonia and other nitrogen compounds plants can use
some nitrogen-fixing bacteria are free-living
some are symbionts
legumes – plants (peas, beans, alfalfa, and clover) with mutualistic relationship with nitrogen-fixing bacteria living in nodules in the roots
bacteria provide usable nitrogen to the plant in the form of ammonia
plant provides food and shelter to the bacteria

31. Prokaryotes play important roles in ecosystems.
bioremediaters – break down pollutants
some bacteria can digest oil, others can digest poison
important role in recycling and composting
biodegradable – able to be broken down by bacteria
many plastics are NOT biodegradable.

32. Summary of Beneficial Bacteria: (not in notes)
*bacteria are decomposers and nitrogen fixers
*bacteria are used to make certain foods like cheese and yogurt.
* bacteria are used in the manufacture plastics and many pharmaceuticals.
* bacteria digest cellulose in animals
* bacteria are used in sewage treatment plants
* bacteria are used to make medications and biological molecules like insulin (a protein – bacteria transcribe and translate the human gene!)

33. 18.6 Bacterial Diseases and Antibiotics
Some bacteria cause disease.
some bacteria cause disease in plants and animals by disrupting the host organism’s homeostasis in 2 basic ways:
invading tissues and attacking cells
making poisons, or toxins, that can be carried by blood through the body

34. Some bacteria cause disease.
tuberculosis (TB) – bacteria invade host tissues and use them for nutrients
Mycobacterium tuberculosis multiply in the lungs, killing white blood cells that respond to the invasion
host’s reaction is to release enzymes that cause swelling; results in lung damage
a healthy immune system can usually defeat a potential TB infection

35. Some bacteria cause disease.
food poisoning –
Staphylococcus aureus – normally live in nasal passages
when transferred to food it results in serious illness
toxin it produces is not destroyed by cooking
Clostridium botulinum – causes botulism which can be deadly due to the toxin produced by the bacteria
usually caused by improper canning of foods contaminated with spores
bulging or dented cans may signal the presence of the bacteria

36. Some bacteria cause disease.
opportunistic infections – normally harmless bacteria can be destructive when introduced to a part of the host that is not adapted to them
example – Streptococcus normally present in our mouth and noses and the surface of our skin, but can become pathogenic in a sore or cut
also causes strep throat

37. Antibiotics are used to fight bacterial disease.
antibiotic – chemical that kills or slows the growth of bacteria, often by stopping bacteria from making cell walls
produced naturally by some species of bacteria and fungi
used as medicine for humans and other animals because we/they lack cell walls
antibiotics don’t work on viruses – they don’t have cell walls either
antibiotics don’t work on Archaea either - they have a different type of cell wall (no peptidoglycan)
overuse of antibiotics can lead to illness if the intestinal “flora” or microbes are wiped out and can lead to resistance

38. Some disrupt other processes & structures unique to bacterial cells
Not all antibiotics attack the cell walls of the bacterium (penicillin does)
Some disrupt other processes & structures unique to bacterial cells
Ex) tetracyclin disrupts protein synthesis in bacteria because of some minor (but important!) differences in the process/structures involved

39. Antibiotics are used to fight bacterial disease.
Gram stain – the Gram stain is a method of using stain to tell two groups of bacteria within Kingdom Bacteria apart. This was an important technique developed which is helpful in not only diagnosing bacterial infectious but also in determining the antibiotic medicine that the doctor chooses to treat the infection.
Gram negative bacteria stain red. These bacteria only have a thin layer of peptidoglycan in the cell wall, but have an extra layer of lipids.
Gram positive bacteria stain purple. These bacteria have a thicker layer of peptidoglycan in the cell wall. Typically Gram + bacteria are easier to kill with antibiotics.

40. Antibiotics are used to fight bacterial disease.

41. Bacteria can evolve resistance.
multi-drug resistant bacteria – serious public health issue resulting from inappropriate and incomplete use of antibiotics
called “superbugs”
resistance is a result of natural selection – bacteria that are unaffected by an antibiotic due to a random mutation survive to produce other bacteria that are also naturally resistant to the same antibiotic (binary fission)
genes for resistance are acquired when plasmids are exchanged during conjugation

42. Bacteria can evolve resistance.
factors contributing to this issue include:
overuse – prescribing an antibiotic for a viral infection is just one example
underuse – failing to take the entire course of antibiotics prescribed
the weakest bacteria are destroyed first, leaving behind those that are more resistant
additional (the entire prescription) may kill all of the bacteria or reduce their numbers to a load your immune system can handle
misuse – feeding them to livestock to increase their growth rate leads to resistant bacteria present in the food as well as in the animals

43. Antibiotic Resistant Bacteria Video Clip
Antibiotic Resistance Video Clip

44. Other diseases caused by Bacteria: (not in notes)
* anthrax
* lyme disease
* E. coli (food poisoning)
* bubonic plague
*typhoid fever *cholera
*strep throat *dental caries (cavities)
*diphtheria *pneumonia
*Salmonella (food poisoning)

45. Yellow bacillus bacteria in the lining of the human nose
Yellow bacillus bacteria in the lining of the human nose. This species causes pneumonia if the person doesn’t have a strong immune system (opportunistic infection).

46. Questions to Ponder
Why are bacteria important organisms in the ecosystem?
What are the shapes and arrangements of bacteria and how can these be used in classification?
In what ways are bacterial beneficial to us? Explain.
Describe bacterial diseases including cause, symptoms, and transmission.