19 Ch 23 and more Bacteria amp Virus Overview Interesting stuff We live with bacteria and viruses constantly but most people dont know much about them In this chapter we learn both the good and bad of each ID: 631918
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Slide1
Bacteria & Viruses
Ch
19,
Ch
23, and more Slide2
Bacteria & Virus Overview
Interesting stuff!
We live with bacteria and viruses constantly, but most people don’t know much about them.
In this chapter we learn both the good and bad of eachSlide3
Today’s Learning Objectives
Know the terms in this chapter.
Remember the 2 kingdoms of prokaryotes.
Know the 3 shapes of bacteria.
What are the 4 ways bacteria obtain energy?
How do bacteria respond to O
2
?
What is the importance of bacteria?Slide4
Bacteria (19-1)
Describe bacteria:
Small (1 – 5 micrometers)
Prokaryotes (organisms w/no nucleus)Single-celledMay cause disease / may be healthfulOldest form of life (3.5 billion years)
Live everywhere
Most are not harmfulSlide5
Research
Louis Pasteur: studied fermentation of yeast to produce alcohol
Went on to invent the process of pasteurization to prevent the spread of small pox
Joseph Lister: introduced the use of disinfectant to clean surgical dressings in order to control infections (1860s)Slide6
Bacteria
Classification (2 kingdoms)
Eubacteria
Large kingdom, much diversityLive almost everywhere
Cell wall contains
peptidoglycan
Example
:
Escherichia coli
(AKA
E. coli
)
Lack organellesSlide7
E. coli
, a Typical
Eubacterium
http://
www.cellsalive.com/animabug.htm
Ribosomes
Pili
DNA
FlagellumSlide8
Bacteria
Archaebacteria
Smaller
kingdom? Cell walls lack peptidoglycan
Examples:
M
ethanogens
live in intestines & mud
Halophiles
live in very salty waters where nothing else can live
Others live in near-boiling waterSlide9
Bacteria
Characteristics used to identify types
Shape
Structures in cell wallsHow they move
How they obtain energySlide10
Bacteria
3 shapes of bacteria
Bacilli
– rod shapedCocci – spherical
Spirilla
– spiral shapesSlide11
Structures in cell walls
Gram-positive bacteria
– have thick peptidoglycan walls, look purple under gram
staining; antibiotics are effectiveGram-negative bacteria – have thin peptidoglycan walls with an outer fatty layer; look pink under gram staining; usually a second cell wall; antibiotics not very effectiveSlide12
Bacteria
How bacteria
move
Some do not moveSome swim using flagellaSome slide on a layer of slime they secrete
https://
www.youtube.com/watch?v=qC5JvOUqMjw
https://
www.youtube.com/watch?v=891M1TH99_8
https://
www.youtube.com/watch?v=R6abZKZ9EGMSlide13
Bacteria
How they obtain energy (4 ways)
Chemoheterotrophs
PhotoheterotrophsPhotoautotrophs
ChemoautotrophsSlide14
Bacteria
Chemoheterotrophs
–
Eat (absorb) chemicals as foodSounds weird, but humans fit this categoryPhotoheterotrophs –Need light for photosynthesis AND need to eat chemicals
Combine them to form more complex organic moleculesSlide15
Bacteria
Photoautotrophs
–
Use light to convert chemicals to energyPhotosynthesisEx.
cyanobacteria
Chemoautotrophs
–
Use chemicals to convert other chemicals into energy
Like photosynthesis, but without light
Ex. bacteria at deep ocean thermal ventsSlide16
Bacteria
Bacteria also differ importantly in how they respond to oxygen
Obligate aerobes
– require oxygen to liveEx. Mycobacterium tuberculosisObligate anaerobes – die if oxygen is presentEx.
Clostridium botulinum
Facultative anaerobes
– can live with or without oxygen being present
Ex.
E. coliSlide17
Bacteria
Bacterial reproduction
Always asexual, can be as often as
every 20 min.Binary fission – bacteria grows to nearly twice its normal size, duplicates DNA, then divides in halfSlide18
Bacteria
Other genetic processes
Conjugation
– can exchange DNA with other bacteria through a conjugation bridgeSpore formation – in unfavorable environments, the bacteria forms a smaller structure with just its DNA and a little cytoplasmIt then goes dormant until survival conditions improveSlide19Slide20
Bacteria
Importance of bacteria in environment
Some
photosynthesize and are basis of food chain
Others are
decomposers
that recycle nutrients from dead organisms
Important role in
nitrogen cycle
Bacteria are the only organisms that can change nitrogen from atmosphere into forms other organisms can use
Called “nitrogen fixation” because it “fixes” the nitrogen so plants and animals can use it
Nitrogen required for life! Component of proteins and DNA.Slide21
Nitrogen CycleSlide22
Bacteria
Human uses for bacteria
Need them in and on our bodies (protection, vitamin production, etc.)
Used in food production ( yogurt, cheese)Used to produce drugs (insulin,
penicillan
)
Other manufacturing
processes (toothpaste, ice cream)Slide23
Today’s Learning Objectives
What are the parts of a virus?
How do viruses get into a cell?
How are the
lytic
cycle and
lysogenic
cycle different?
Form an opinion on whether viruses are living or nonliving, and support that opinion with facts.Slide24
Viruses (19-2)
Virus
– a particle of nucleic acid, protein, and sometimes lipids
Viruses enter cells of other living things, hijack their nuclei and other organelles, and produce copies of themselvesBasically act like parasitesVery tiny, much smaller than bacteria
pathogenicSlide25
Viruses
Virus structure
Core of DNA or RNA surrounded by a protein coat
capsid – the protein coat of a virusMay also have fatty layer tooShape varies:Complex and geometric
Simple and irregularSlide26Slide27
Viruses
Bacteriophage
– virus that infects bacteria, commonly studied example of a virusSlide28
Viruses
How viruses
get into a cell
The capsid and the cell of the host have to matchProteins on the capsid must match receptors on the cell, or vice versaWhen the proteins & receptors randomly come in contact, the virus injects its DNA or RNA into the cell
Once inside the cell, it has options
…
Not considered alive because…..Slide29
Viruses
Two different types of viral infections
Lytic infection
Lysogenic infectionSlide30
Viruses
Lytic infection
– in this type of infection, the virus immediately takes over the host’s cell and uses its organelles to make copies of itself
When enough copies are made, it splits (or “lyses”) the cell, killing it, and releasing the new viruses100 viruses in 20 minutes
AnimationSlide31
Viruses
Lysogenic infection
– In this case the virus merges its DNA with the host’s DNA, and could stay there for months or years before causing problems
After some period of time, the viral DNA is activated by somethingIt then begins a lytic infection
AnimationSlide32
Viruses
Retroviruses
– viruses with RNA instead of DNA
Important because they have unusual ability to make DNA from RNA (reverse transcription)HIV is an example of this type of virusSlide33
Are viruses alive?
Yes because:
They reproduce
(only within a host)They use energy
(
only within a host)
They have genes
They evolve
No because:
They are not made of cells
They cannot live or reproduce without the host
They do not grow, obtain energy, or respond to the environmentSlide34
Today’s Learning Objectives
Know the two methods bacteria use to cause disease.
Describe three methods humans use to fight bacterial disease.
List 4 diseases caused by viruses.
We’ll go into detail about 5 viral diseases. Pick one and describe 3 details about it.
What are
prions
and
viroids
?Slide35
Viral & Bacterial Disease (19-3)
Only a few bacteria and viruses cause disease
Most bacteria are harmless
Pathogens – disease-causing agents
Enter us: water, air, touch, food, insectsSlide36
Viral & Bacterial Disease
Examples of diseases caused by bacteria
Tuberculosis
Strep throatLyme disease
Tetanus
Bacterial meningitis
Anthrax
Pneumonia (some types)
Chlamydia
Botulism
SalmonellaSlide37
Viral & Bacterial Disease
Two methods bacteria cause disease:
Some damage cells directly and injure the organism
Ex. bacteria that causes tuberculosisSome produce toxins that make the organism sick
Ex. the bacteria that causes strep throat and scarlet
fever
Botulism
-
https://www.youtube.com/watch?v=A-_
QTgKwHEwSlide38
Viral & Bacterial Disease
Three methods of fighting bacterial diseases
Body’s immune system will fight infections
Vaccine
– a solution of weakened or killed pathogens that prepares the body’s immune system to fight off disease
Antibiotics
– chemicals that block the growth or reproduction of bacterial invadersSlide39
Viral & Bacterial Disease
Methods of preventing bacterial exposure
Sterilization
– using high temperatures to kill bacteria and bacterial sporesDisinfectant – using a chemical that kills pathogenic bacteriaFood processing – using heat, refrigeration, or pressure to prevent bacteria from growing in foodSlide40
Viral & Bacterial Disease
Viral diseases
Viruses can only enter a specific type of cell
The symptoms of the disease depend on which type of cell it enters and destroysEx. if it kills nerve cells, could cause paralysis (Poliovirus)Ex. if it attacks white blood cells, it could prevent immunity (HIV)
Ex. if it disrupts the DNA of a normal cell in a specific way, it could make it cancerousSlide41
Viral & Bacterial Disease
Viruses cause a wide range of human disease:
The common
cold,
Influenza,
Chickenpox,
Smallpox,
Rabies, AIDS,
Cervical
Cancer,
Ebola, West Nile,
Herpes
And many more
Also animal diseases:
Foot and mouth disease (cattle)Also plant diseases:Tobacco mosaic virusSlide42
Defense Against Viruses
Antibiotics do not work
Interferon can work ( body natural defense)
Drugs that block cell enzymes for DNA replication like AZT (slows diseases, very toxic)VaccinesSalk: developed first polio vaccineSmall pox: killed ½ the people who contracted itSlide43
Influenza #1 of 5…
Influenza
= the flu
mild to severe illness, can be lethalEvery year in the United States, on average:
5% to 20% of the population gets the flu;
more than 200,000 people are hospitalized from flu complications, and;
about 36,000 people die from flu.
Worst Flu in 20
th
Century
-
https://
www.youtube.com/watch?v=8NRTC1BlHg0Slide44
Bird
Flu #2 of 5
In the news… Bird Flu or Avian Flu
Currently only infectious among birds, but about 584 people have caught it anyway,
385 of
those have died (what % fatal?)
Scientists worried virus will mutate and become infectious among
people (like H1N1 did)Slide45
Smallpox Eradication
#3 of 5
1967 WHO (World Health Organization) started campaign to wipe out smallpox
Smallpox killed
50
% of people who got it, and left rest badly scarred, some blind
WHO vaccinated people in poorest countries
One by one, countries reported no more infections
Smallpox
declared eradicated in 1980Slide46
HIV Treatment, #4 of 5
HIV is virus that causes AIDS
Treatment, but no cure
“Cocktail” of antiviral drugs to fight off quickly adapting virusSlide47
Emerging
viruses #5 of 5
Emerging viruses
– viruses that are relatively new to humans and are life threatening
Hantavirus – Southwestern US
HIV - Global
Ebola – Central
Africa (massive, 90%)
SARS – Global
Avian
flu
– Asia, Europe,
Africa
Swine flu (H1N1
)ZIKA (not sure yet)Slide48
Not quite viruses…
Viroids
–
RNA with no capsid, cause plant diseasePrions –Misshapen proteins that cause disease
Cause diseases like:
Scrapie (in sheep)
Chronic Wasting Disease (deer)
Bovine Spongioform encephalopathy (BSE) AKA: Mad Cow Disease
Creutzfeld Jakob Disease (CJD)