Ch. 18—Prokaryotes

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

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

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

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

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

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

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

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

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

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

BACTERIA DO NOT HAVE CILIA!!!!

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)

Bacterial Shapes bacillus coccus spirillum

Structural Comparisons of Bacteria and Archaea Label: coccus bacillus spirillum

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

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:

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

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

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

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.

binary fission – prokaryotic asexual reproduction

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

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)

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

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.

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

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

Cyanobacteria

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

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.

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!)

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

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

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

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

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

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

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.

Antibiotics are used to fight bacterial disease.

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

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

Antibiotic Resistant Bacteria Video Clip Antibiotic Resistance Video Clip

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)

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).

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.