TAXONOMY OF BACTERIA Instructor Terry Wiseth MICROBIOLOGY Northland Community & Technical College.
Chapters 19,20,21 Start @ Chapter 19 Virus and Bacteria Microbiology.
-
Upload
jared-black -
Category
Documents
-
view
220 -
download
0
Transcript of Chapters 19,20,21 Start @ Chapter 19 Virus and Bacteria Microbiology.
Chapters 19,20,21
Start @ Chapter 19
Virus and Bacteria
Microbiology
Viruses… The Living Dead?
• Living because…– Reproduce–Has DNA/RNA “Blueprint of Life”– Evolves
• Non-living because…– Require a host (Parasitic)– To reproduce, they use the host– It does not have cells
Sizes
• Most are so small they can’t be seen with normal microscopes– Require Electron microscopes
• Are smaller than Monerans (Bacteria)
Viral Shapes
• Spirals, Polygons, rods, bullets, needles
• Bacteriophages
Viral Parts• Capsid: outer protein coat– Allows the virus to enter a cell– “Tricks” the cell
• Genetic Material: DNA or RNA
• Envelope: Protective layer around the capsid.–NOT ALL VIRUSES HAVE THESE– Comes from the host cell membrane
Other facts about Viruses
• Almost all organisms have at least one virus that infects them
• They are “host-specific”– Usually only infect one species
Types of Viruses
• Bacteriophages
• DNA Viruses
• RNA Viruses
• Retroviruses
Bacteriophages
• Infect Bacteria Only
DNA Viruses
• Have DNA as their genetic material
Single-stranded DNA virus:
Canine Parvovirus
Double-stranded DNA virus:
Chicken pox (Varicella zoster)
DNA Viruses
Herpes Virus in a host cell
Human Papilloma virus: causes warts
Adenovirus: causes some colds
RNA Viruses• Has RNA as genetic
material
Rhinovirus: Common Cold
Paramyxovirus: Measles and Mumps (in a host cell)
Rabies virus
Retroviruses
• RNA as genetic material
• To replicate, they convert the RNA back into DNA and use host to make more RNA
HIV (Human immunodeficiency virus)
How Viruses Infect
• Two ways it can happen
• Lytic Infection
• Lysogenic Infection
Lytic Infection (The Outlaw)
• Simple Version: Virus enters a cell, replicates, and bursts the cell
1. Landing: Virus lands on Cell
2. Injection: Virus injects DNA into Cell
3. Replicate: Cell makes RNA out of Virus’s DNA, and shuts down Cell
4. Assemble: Cell then puts together the virus components
5. Burst: So many viruses are created that the cell lyses, or bursts.
Lysogenic Infection
• Virus DNA is made indefinitely by the cell
• Virus places its DNA into the host’s DNA so when replication happens it copies both the virus and the host
• Prophage:Viral DNA in the Host DNA
• Eventually will become Lytic
Drawing/Picture
Bacteria
• Prokaryotes: unicellular organisms that lack a nucleus– Bacteria
• Prokaryotes are now classified as Monerans (Kingdom: Monera)
• Divided into two groups: Eubacteria and Archaebacteria
Eubacteria• Larger of the two kingdoms (in both
size and variety)
• Live almost everywhere
• Surrounded by a cell wall– Cell wall contains peptidoglycan
• Other parts: Cell membrane & cytoplasm
Archaebacteria• Same structure, different chemically
• They lack peptidoglycan and have different membrane lipids
• DNA sequence is more closely related to eukaryotes than eubacteria
Archaebacteria
• Live in extreme conditions• Examples:–Methanogens: Produce methane gas• Live in stomachs and thick mud
– Salty conditions– Boiling water– Sulfur pits– Etc…
Ways to Identify a Prokaryote
• Shape
• Chemical Components of Cell Wall
• Movement
• Way they get Energy
Shapes
• Coccus: Round bacteria• Example: Staphylococcus sp.
Shapes
• Bacillus: rod bacteria– Example: Bacillus anthracis
Shapes
• Spirochetes: spiral bacteria– Example: Treponema pallidum
Cell Walls and Gram Staining
• Two different types are found in eubacteria
• We can pick them out using a method called Gram Staining – (We will do this if we get something to
grow!)
Gram Staining Steps• Two dyes: violet and red (counterstain)
• Violet: Applied first– Stains peptidoglycan in the cell wall
• Wash with alcohol– If color stays: Gram Positive– If color washes away: Gram Negative
• Red is then applied to make Gram Negative visible with pink color
Movement
• No movement
• Flagella: Whip-like structure
• Lash
• Snake
• Spiral
• Glide
Ways to Obtain Energy• Two main groups
• We have already talked about!
• Heterotrophs: Energy by consuming others/organic molecules
• Autotrophs: Make their own food
Bacterial Heterotrophs
• Chemoheterotrophs: Obtain energy solely from organic molecules–Most animals are this kind too!
• Photoheterotrophs: Photosynthetic, get energy from the sun but need others to get their carbon from
Bacterial Autotrophs
• Photoautotrophs: Carryout photosyntehsis– Require light source– Ex: Cyanobacteria: chlorophyll a
• Chemoautotrophs: Carryout Chemosynthesis– Do not require light
Getting that Release
• Obligate aerobes: Requires oxygen– Ex: Mycobacterium tuberculosis• Causes Tuberculosis
• Obligate anaerobes: Do not require oxygen– Ex: Clostridium botulinum• Soil bacteria that can work its way into food
if not properly sterilized!
Special Release• Facultative anaerobes– Facultative: Function in different ways
• Can switch between living in oxygen or not (respiration or fermentation)
• Means they could live practically everywhere
• Ex: E. coli: Large intestine to sewage
Bacterial Reproduction (3 way)
• Binary Fission: – Doubles in size, replicates DNA and
divides in half.
• Conjugation: – Exchange of DNA between bacteria– Hollow tube connects bacteria– Responsible for genetic diversity
Spore Formation
• Occurs when environment is unfavorable
• Endospore: thick internal wall that sections off the DNA with cytoplasm
• Spores can last until the conditions are acceptable to grow in
• Ex: Bacillus antracis: Anthrax
Importance of Bacteria
• Producers that produce energy
• Decomposers:– If materials did not cycle in the
environment, life would not exist
– Sewage treatment: Turns trash into purified water, carbon dioxide, nitrogen, and fertilizers
Nitrogen fixers
• We’ve discussed this with the nitrogen cycle but lets see what we remember
• What do we need nitrogen for?• What is the process takes it from air?
• Symbiotic: Rhizobium and legumes
Human Uses
• Bacteria is in food and beverages– Ex: Yogurt, Dairy products, Vinegar, Sausage,
Pickles, anything that ferments (usually)
• Oil spills: Certain ones digest petroleum
• Our Digestion: E. coli: Makes a number of vitamins that we cannot produce
The Medical World
• Genetic Engineering
• Bacillus thuringiensis–Main ingredient in Bt-Corn– Genetically engineered from soil
bacteria to be placed into corn DNA– Kills insects by releases a toxin that
affects insects and causes their stomachs to burst.
Only a few bad eggs…
• Most bacteria and viruses don’t harm
• The ones that do are called PATHOGENS– Disease-causing agents
• Disease: result of pathogen infecting the host
What do microorganisms need?
• Each species has an OPTIMUM– Temperature– pH– Air– Osmotic Pressure–Water– Nutrients
How can we prevent them from getting these requirements?
• Heat (sterilize)• Change pH• Add salt or sugar • Remove oxygen (canning)• Remove water by
Dehydrating foods
How do we spread diseases and how do we stop them?
• Five methods for spreading disease.– AIR– FOOD–WATER– PERSON to PERSON– VECTORS- insects
How does an infection makes us sick?
• What they do: Grow and Reproduce– Destroys cells– Release toxins– Block passages
• What we do: – Crummy Article
Germ Theory of Disease 1857
Louis Pasteur• Eliminates theory of spontaneous
generation• Saves the wine Industry in France• Proposes that there is a relationship
between a microorganism (pathogen) and a disease
• Develops– Pasteurization– Vaccines for anthrax and rabies
Koch’s Postulates 1876
Find suspect organism
Isolate suspect and grow in pure culture
Inject pure culture into healthy subject and get the same disease symptoms
Re-isolate the same suspect organism and grow it in pure culture
Vaccines:
• Treatment for viruses
• Taken as a preventative method
• Cannot help you once you have the disease
• Viruses can become resistant to these, but it is not usually a fast process
• Human production
Antibiotics:
• Treatment for bacterial infections
• Taken once you have the disease
• Cannot be used as a preventative
• Bacteria can easily become resistant to these
• Bacteria and some fungi produce these
Vaccines
• Involves your immune system being stimulated
• Dead or weakened antigen (foreign particle)• Engulfing cells and antibody producing cells
destroy the antigen• Memory cells prepare for another infection– Response to virus is faster and stronger the
second time
• Adds to the health of the community
Antibiotics
• Work ONLY on bacteria– Bacteria are prokaryotic, we are eukaryotic– Bacteria have a cell wall, we do not.
• These help, but our immune system still has to “clean-up”
• Examples:– Penicillin – stops cell wall
formation– Tetracycline – stops protein synthesis– Ciprofloxacin – stops DNA replication
Proper use of antibioticsPrevents Resistance
Only taking them for bacterial infections
Taking pills on time
Taking all your prescription
Concentration of Bacteria at which you feel better =====
Time in DaysShot of Penicillin- Pill taking intervals – missed interval
Concentration of antibiotic -
Effective concentration of antibiotic ---
Concentration of bacteria ……C
on
cen
trati
on
Antibiotic Resistance
• Development of Resistance– Alter the antibiotic– Alter the target or structure– Pump out the antibiotic
• Developing new anti-resistance antibiotics– Target the mechanism that confers resistance
• Stop alteration of antibiotic• Stop alteration of target• Stop the molecular pumping mechanism
Stop the Spread of antibiotic resistance
Do not demand antibiotics
Take them exactly as prescribed
Wash fruits and vegetables(no such thing) thoroughly; avoid raw eggs and undercooked meat, especially in ground form
Use soaps and other products with antibacterial chemicals only when protecting a sick person whose defenses are weakened
Viroids
• Single-stranded RNA molecules that have no capsids
• Infect host, produces more viroids
• Disrupts metabolism, resulting in smaller growth of plant
Prions
• Tiny virus-like particles like contain only proteins usually found in the brain
• Scrapie• Kuru• Mad cow disease
The BIG picture
• Diet• Rest• Exercise both aerobic and resistance
• Personal Cleanliness e.g. wash your hands
• Proper Preparation and storage of food– It Must Have Been Something You Ate
• Environmental Cleanliness pollution, filth
• Annual Physical
Big Picture cont…
• Report symptoms promptly to a responsible person
• Follow physicians instructions– antibiotics
• Vaccinations: Vital– The Vaccine Conundrum