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Chapter 19 Bacteria and Viruses Notes.notebook
1
April 06, 2016
Feb 58:59 AM
Chapter 19 Bacteria and Viruses
Section 1 Bacteria
Key ConceptsHow do the two groups of prokaryotes differ?What factors are used to identify prokaryotes?What is the importance of bacteria?
BacteriaProkaryotes lacks a nucleus and membrane bound organellesMicroscopicRange in size from 15 micrometer
1 meter stick is cut into a million pieces for 1 micrometeror 10,000 pieces for a centimeter
Largest bacteria is 500 micrometer long
Kingdom Only one kingdom Monera until recently now 2
EubacteriaLarger KingdomLive everywhereCell Wall contain Peptidogylcan a carbCell Membrane
ArchaebacteriaChemically different from EubacteriaCell Wall but lack PeptidogylcanDifferent Cell Membrane LipidsLive everywhere even harsh conditions
extreme heat, gas, salt water, fresh water, thick mud,
Identifying Prokaryotesshape, chemical nature of their cell walls, their movement, how
they obtain energy
ShapeBacilli
Bacilli pluralBacillus singularRod Shaped
CocciCocci pluralCoccus singularSpherical Shaped
SpirillaSpirilla pluralSpirillum singularSpiral Shaped
Cell Walltwo different types use a Gram stain to tell differencePeptidoglycans in cell wall hold stain Grampositive Stain is washed out due to thin Peptidoglycan layer Gramnegative
Grampositive GramnegativeRodshaped Rod Shaped Violet stained cocci Grampositive Unstained Pink/Red Gramnegative
MovementIdentified by whether they move and how they moveFlagellaMultiple directions snake, or spiral forwardSome move across a layer of slime they secrete
Obtain EnergyMost are heterotrophs: Chemoheterotrophs / Photoheterotrophs
ChemoheterotrophsChemoheterotrophs are unable to synthesize their own organic molecules. Instead, these organisms must ingest carbon molecules, such as carbohydrates and lipids, synthesized by other organisms. They do, however, still obtain energy from the oxidation of inorganic molecules. Chemoheterotrophs are only able to thrive in environments that are capable of sustaining other forms of life due to their dependence on these organisms for carbon sources.
PhotoheterotrophsUse sunlight for energyMust take in organic compounds as a carbon source.Can not use CO2 as their only carbon source.
AutotrophsChemoautotrophs
Make organic molecules from CO2.Do not require light as a source of energy because they
use chemical rxns.Photoautotrophs
Use sunlight to convert CO2 and H2O to carbon compound and O2.
Releasing EnergyAll bacteria need energy. How they get energy depends on the bacteria. Some need oxygen and some do not. Some it doesn't matter. It does this through cellular respiration and fermentation.
Which way requires oxygen to make energy? And which waydoes not?
Obligate aerobesobligate = requiredrequire oxygen
Obligate anaerobesdo not require oxygen and may be killed by it
Facultative anaerobesdoes not matter, will do cellular respiration if oxygen andwill do fermentation without oxygen
Growth and ReproductionConditions need to favorable for bacteria to grow and reproduce. Even though bacteria can develop in a variety ofconditions from the Arctic to hot springs, its optimal growth is between 40o to 140o.
Look on page 475 for examples.Binary Fission
AsexualBacteria grow until it doubles in size then dividesForms 2 identical daughter cells no exchange of DNA
ConjugationBridge forms between to cells and an exchange of DNA
occursIncreases genetic diversity in populationsDoes not increase population of bacteria
Why is this not considered a type of sexual reproduction?
Spore FormationIf conditions are not right, many bacteria will form a spore
that protects the bacteria. One method of survival.Endospore thick wall that surrounds and protects
Why are bacteria important?Decomposers
break down dead matter and recycle nutrients to soil, water and airbreak down sewage so we can recycle the water, nitrogen
and CO2
Nitrogen FixersNitrogen Fixation
converting nitrogen gas into ammonia or other nitrogencompounds
humans need nitrogen to make proteins, but we can not get it from the air but we get it by eating plants and
animals that have eaten plants
Human Uses of Bacteriaoil spillsremove waste products and poisons from water synthesize drugs and chemicals through genetic engineeringfoodmedical usesvitamins
http://www.ted.com/talks/bonnie_bassler_on_how_bacteria_communicate?language=en
Chapter 19 Bacteria and Viruses Notes.notebook
2
April 06, 2016
Feb 1910:53 AM
Section 2 Viruses
Key ConceptsWhat is the structure of a virus?How do viruses cause infection?
Look at Figure 199. Page 479Virus Structures
Look for Differences/Similarities in the different viruses.
Differences Similarities
What is a Virus?Virus = poisonNonlivingNot made of cellsComposed of DNA or RNA cells only have DNAProtein Coat surrounds genetic material = CapsidMany Shapes and Sizes
Reproduce ONLY by infecting living cells1. Surface Proteins bind with receptors on cells and trick the cell into letting the virus inside. Virus cells are specific to the cells they infect. Plant viruses infect plant cells and animal viruses infect animal cells.
Bacteriophages infect bacteria cells
2. Once inside the cell the virus genetic material takes over and the cell begins to replicate the virus genetic material.3. Host cell may or may not be destroyed right away.
Once inside two processes may occur Viral Infection
Lytic InfectionOverview
Virus enters cell, causes cell to make copies of its genetic material and proteins, then the cell is destroyed
Steps1. First, the bacteriophage attaches to the bacterium's protein coat.2. The bacteriophage then injects its DNA into the bacterium.3. The bacteriophage takes over the bacterium's metabolism causing synthesis of new bacteriophage proteins and nucleic acids.4. Bacteriophage proteins and nucleic acids assemble into complete bacteriophage.5. Bacteriophage enzyme lyses the bacterium's cell wall, which releases new bacteriophage that attack other cells.
Lysogenic Infection page 481Virus enters cell, DNA incorporates itself into the DNA of
the host cell (Prophage), then the new DNA is replicated, the host cell is not destroyed immediately
Virus will lay dormant until a trigger stimulates prophage to remove itself and begin synthesis of the DNA and start the lytic cycle.
RetrovirusesContain RNAInfect and produce a copy of the DNA which is then inserted
into the cells DNA
Retrovirusescontain RNA for their genetic informationwhen it enters cell, they produce a DNA copy of their RNA which
acts as a prophage, after a signal is give to produce the DNA the host cell is destroyed
responsible for some cancer cells
Viruses and Living Cellsviruses can be a parasitemust infect a living cell to grow and reproduceviruses smaller than the smallest cell
Look at Figure 1911Compare Viruses and Cells
http://www.wimp.com/virusinvades/
Chapter 19 Bacteria and Viruses Notes.notebook
3
April 06, 2016
Mar 211:32 AM
https://www.youtube.com/watch?v=eMrFV2rnHlo