Bacteria and Viruses PP

7/30/2019 Bacteria and Viruses PP

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Chapter 2:

Prokaryotes and Viruses

Left:Halorespiring bacteria that feed offof solvents dumped in great lake, breaking

down toxic substances and giving off

harmless bi-products


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The viruses-Are not made of cells and have no cell parts.1. Protein coat wrapped around a chromosome-like part

2. Cannot reproduce by itself

Genetic material

is either DNA or RNA

Host.An Organism that

provides food for aParasite

An organism that lives in / on

another living thing and gets food

from it


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What traits are used to classify viruses?

Type of host virus infects (tobacco mosaic virus only infects

tobacco plants)

Part of body the virus infects (rabies virus (above right) onlyinfects nervous system of mammals)

Also shape of protein coat and size of virus are ways toclassify


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Virus shapes

(a)Helical virus (rod-shaped), (b)Polyhedral virus (most are adenoviruses), (c)

Animal virus (most have envelope), (d)Bacteriophage (infect bacteria)


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AIDS.Acquired Immune deficiency syndrome. Destroys thebodys immune system. Spread by:

Sexual intercourse

Blood products

Contaminated needles

Pregnant woman to developing fetus

Right: HIV particles (blue) attacking a T-helper cell


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How do viruses get into plant cells?

Spread by wind or by insects (seewinged aphid on right)

Can prevent viruses from spreading

further by tracking larvae andegg rings on diseased leaves(see below right)


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Life cycle of a bacteriophage(bacterial virus)

1. Bacteriophage virus binds to

receptor on hosts cell wall

2. Viral DNA is injected into bacteria

3. The bacteria host begins toreplicate viral DNA


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Life cycle

4. Production of viral components and

enzymes progresses

5. And viruses fully assemble

6. Cell breaks open (osmotic lysis) and

bacteriophages are released to invade other cells


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Smaller than virus; do not have protein coat But cause infections (usually in plant)

Prion-proteins necessary for operation of brain cells

Build up inside brain Scrapie (found in sheep) and Mad Cow Disease (BSE),

which started because ground up sheep tissue that had been infected

with Scrapie were fed to cattle


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Controlling viruses

. Chemical substance that interferes with the

way viruses reproduce. When they burst

open, infected cells

release interferon to

warn other cells

Specific to each

species ie) Horse

interferon will not

work on humans


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Antibodies and vaccines

White blood cells (WBC) can make antibodies that attach to

viruses and bacteria.(all pics of antibody structure)1. Destroy directly(bottom middle, antibody attack)

2. Captures; waits till WBC can surround and destroy

3. Specific to only one type of virus or bacteria


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Vaccines

Vaccinesare substances made from weakened or dead viruses

Breaking headlines:

S. Africa launches biggest AIDS vaccine trial (Thu Feb8, 2007 2:33 PM ET)

Bottom right: Feb. 2, 2007 in Austin, TX; vaccine

Gardasil,. Gov. Rick Perry ordered that schoolgirls in

Texas must be immunized with the vaccine to helpprevent the sexually transmitted virus that causes

cervical cancer. It would make Texas the first state

to require the shots.


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Moneran Kingdom(Archaea, eubacteria, blue-green algae)

Bacteria- prokaryotic (single-celled, without a nucleus)organisms too small to be seen with a microscope

There are 4 ways to classify prokaryotes

Below:E.Coli

Above: Anthrax

Above: MSRS bacteria


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Characteristics of prokaryotic cells

1. Capsule (sticky outer layer, prevents from drying out)

2. Reproduce asexually via (dividing in two)

3. Cell wall present in most species

4. No nucleus

5. Some move with a flagella (whip-like tail)

Left: plasmid

(circular piece

of DNA foundin most bacteria)

Right:

prokaryotic cell


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Growth & Reproduction

Binary Fission

Asexual no exchange

or recombination of DNA

Doubles in size, duplicates

DNA, divides in half

Produces 2 identical

daughter cells


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Process of fission


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Growth & Reproduction

Conjugation Exchange of DNA

Hollow bridge forms between cells

Transfer of DNA increases genetic diversity

Spore Formation When growth is unfavorable

Endospore: thick internal wall that enclosesDNA & portion of cytoplasm

Can remain dormant for months or years


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1. Shape

Coccus. Spherical (top right)

Bacillus.Rod-shaped(bottom left, anthrax)

Spirillum.One or more twists (bottom right)


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2. Type of cell wallGram + (stays purple) and Gram(loses color and the

counterstain turns pink)

Left: Gram + and Grambacteria; purple dye adheres

glycocalyx in periplasmic space


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Gram + and Gram -


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3. Movement

Some do not move

Some are propelled

by flagella

Spiral forward

Glide along slime-like material


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4. Obtaining Energy

Heterotrophs get energy by consumingorganic molecules made by otherorganisms (consumer)

Chemoheterotrophs take in organicmolecules for both energy and carbon

Photoheterotrophs use sunlight forenergy, need to take in organiccompounds for carbon


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DONT NEED TO WRITE ANYTHING DOWN

Glycocalyx. Consists of polysaccharides, polypeptides or both.

When highly organized, it forms a capsule

Flagella and Piliare also useful for attaching to surfaces and motililty

Above left: G. metallireducens, bacteria that can spontaneously grow flagella to find

metal food source;Above right: slimy appearance on bacteria from capsule formation


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Kingdom Archaebacteria

Live in extremely harsh environments Oxygen-free environments

Salty environments

Lack peptidoglycan in

cell walls Different membrane

lipids

Some DNA sequences

more like eukaryotes


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Archaebacteria cont.Extreme thermophiles.heat-lovers

Nearly all are anaerobes requiring S2 for e-

Can survive at temperatures up to 80 C

Locations: volcanoes, hot springs, coal mines

Right:Thermus aquaticus, found in

hot sulfur springs in Yellowstone;

scientists can utilize heat sensitive

DNA polymerase extracted from

these bacteria


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Extreme halophile.salt-lover

Located in Great Salt Lakes, Dead Sea and other extreme salty regions

Right: chemical plant in Pittsburgh

(at northwest end of Owens Lake)

colored red by halophiles


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Methanogens.methane makers

Located in gut of termites and mammals, stockyards and swamps

Use CO2, H2 and/or alcohol for energy

Recently geologists discovered

35 BILLION tons of frozen

methane gas at bottom of sea

Right:Methanococcus voltae; methanogen

that uses H2 gas to produce methane


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Eubacteria

Larger kingdom Live in fresh water, salt water, on land, in

human body

Cell wall contains peptidoglycan

Right:Bacillus anthracis


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Eubacteria.

Above: Salmonellais a gramchemoheterotroph

Top Right:Rhodospirillum; purple


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Eubacteria vs. archaebacteria

are classified into the kingdoms of

Thickmud

Animaldigestive

tracts

Saltylakes

Hotsprings

live in harshenvironments such as

include a variety oflifestyles such as

Bacteria

Living insoil

Infectinglarge

organisms


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Kingdom Eubacteria-true bacteriaPhotoautrophs. Cyanobacteria (blue green algae)


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chemoheterotrophs. Most bacteria fall into this category

Range from decomposers and nitrogen converters to sources of foodand antibiotics

Lactobacillus rhamnosus (right) shown to be effective in treatment of several forms of diarrhea in humans

Lactobacillus casei (left) are found in dairy, plant products and digestive tract of humans/animals.
http://www.erc.on.ca/research/files/current_research/uofg_current_research/curr_res2_lactobacillus_eval.htmlhttp://genome.jgi-psf.org/draft_microbes/lacca/lacca.home.htmlhttp://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=126770http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=126770http://genome.jgi-psf.org/draft_microbes/lacca/lacca.home.htmlhttp://genome.jgi-psf.org/draft_microbes/lacca/lacca.home.htmlhttp://www.erc.on.ca/research/files/current_research/uofg_current_research/curr_res2_lactobacillus_eval.htmlhttp://www.erc.on.ca/research/files/current_research/uofg_current_research/curr_res2_lactobacillus_eval.html


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Releasing Energy

Obligate aerobes

Require oxygen to live

Obligate anaerobes

Live in the absence of oxygen

Facultative anaerobes

Do not require oxygen but are not killed by itspresence


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more chemoheterotrophs

Most pseudomonads (above) are free-living organisms in soil and water; play an importantrole in decomposition, biodegradation, and C and N cycles; move by polar flagella

Above L:E. colifound in intestine of humans; also have pathogenic strains ie) 0157:H7

that cause food poisoning Above R: D. radioduransresists high radiation doses


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more chemoheterotrophs

Clockwise, starting in top R:

1.Clostridium botulinum cause

food poisoning; can disrupt

breathing and can lead to death;

2. C. tetanicauses tetanus; can form

endospores, which resist extreme

conditions; 3.Tetanus causes muscle

spasms such as lock jaw and arched

spine; death occurs when spasms

affect breathing;4. Borrelia

burgdorferireside in deer ticks

and can causes lyme disease; 5.

Rickettsia rickettsiicauses

Rocky mountain spotted fever,

another tick rash-causing disease


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Even More bacteriaBottom right: Magnetotactic bacteria have a chain of magnetite that acts

like a compass, enabling cell to navigate which way is North

Bottom left: myxobacteria have

fruiting bodies that reproduce by releasing

spores

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