Download Ch. 19 Bacteria and Viruses

UNIT VI
Chapter 19
Bacteria and Viruses
Chapter 19: Bacteria and Viruses
I. Bacteria
A. Prokaryotes- (single-celled organisms that lack
a nucleus)
1. Classifying Prokaryotes (2 main groups)
a. Eubacteria- (larger of
two Kingdoms) includes
wide range of organisms
with different lifestyles.
Cell wall of peptidoglycan
(a carbohydrate)
b. Archaebacteria- (may be ancestors of eukaryotes)
cell wall lacks peptidoglycan. DNA more like those of
eukaryotes than eubacteria. Live extremely harsh
environments (e.g. Around thermal vents,
methanogens in digestive tracts of animals
c. Cell Walls- two different types in Eubacteria
1. Gram positive- bacteria stains violet
blue; peptidoglycan is made of carbs
2. Gram negative- bacteria stains red;
cell wall Is made of lipid (fats)
Two different types of cell walls
are found in eubacteria. A
method called Gram staining is
used to tell them apart. Bacterial
cells with a cell wall containing
mainly peptidoglycan absorb
only violet dye. Other bacteria
have a second, outer, layer of
lipid and carbohydrate molecules
and absorb only the red stain.
d. Identifying Prokaryotes (by shapes, chemicals of
cell wall, way they move, method of obtaining energy)
1). Shapes- bacilli (rod-shaped), cocci
(spherical), and spirilla (corkscrew-shaped)
2). Movement- some move by flagella, or glide
through slime-like material, or no movement
3). Obtaining Energy
a). Photoautotrophs- photosynthetic
(make own food)
b). Chemoautotrophs- obtain energy
from inorganic molecules. Eat chemicals
(e.g. Hydrogen sulfide gas)
c). Heterotrophs- includes most
prokaryotes. Obtain energy by taking in
organic molecules and breaking them
down.
d). Photoheterotrophs- both photo.
and hetero.
4). Releasing Energy
a). Obligate aerobes- require constant supply of
oxygen to live (cellular respiration)
b). Obligate anaerobes- must live in absence of
oxygen (e.g. Clostridium botulinum) rely on
fermentation
c). Facultative anaerobes- do not require oxygen
but are not poisoned by it either. Can use either
cellular respiration or fermentation.
Botulism, a kind of food poisoning, is
caused by the bacterium Clostridium
botulinum. This type of bacterium is often
found in foods that have not been properly
sterilized.
5. Growth and Reproduction
a. Binary fision- divides in half producing identical
daughter cells (asexual)
b. Conjugation- form bridge
between two cells and
transfer genetic materialincreases genetic diversity
(sexual)
c. Endospore- when conditions bad, bacteria form
thick internal wall enclosing DNA and portion of
cytoplasm. Can remain dormant for months or years
Anthrax spores
B. Bacteria in Nature
1. Decomposers- return nutrients to ecosystem
2. Nitrogen fixers- convert atmospheric nitrogen
into form that the plants can use –ammonia (NH3)
Many plants have symbiotic
relationship with nitrogenfixing bacteria. The knoblike structures on the roots of
this soybean plant are called
nodules. Within these
nodules are the rod-shaped,
nitrogen-fixing bacteria
Rhixobium
3. Bacteria and disease- only a few cause
disease (pathogens)
The “Dance of Death”
was common during
the bubonic plague.
a. Some damage tissues of infected organisms by
directly breaking them down for food. (e.g. Flesh
Eating Bacteria)
b. Some release toxins (poisons) (e.g. botulism)
c. Many bacterial diseases can be prevented by
stimulating bodies immune system with vaccines
Vaccines can be used to
prevent infection by the
tuberculosis bacterium
Mycobacterium
tuberculosis
d. Antibiotics- compounds that block growth and
reproduction of bacteria
e. Human uses of Bacteria- used in production of
variety of foods (cheese, yogurt, buttermilk,
sourcream, etc. )
f. Controlling bacteria- can be killed by heat or
chemicals (sterilization)
The practice of using antiseptics in the care and treatment of wounds was begun
by the English surgeon Joseph Lister in 1868. Basing his work on the findings of
the German physiologist Theodor Schwann and the French biochemist Louis
Pasteur, Lister disinfected surgical and accidental wounds with a solution of
carbolic acid, and in five years reduced the death rate from major amputations from
45 percent to about 12 percent. Many other antiseptics have come into use, among
which the most important are mercury dichloride, iodine, boric acid, alcohol, the
hypochlorites, mercurochrome, and Merthiolate. Chlorine is used in the sterilization
of water, especially in public water systems and swimming pools.
Streptococcus
Tooth decay
mutans
Borrelia
Lymeburgdorferi
disease
Leprosy- this chronic
infectious disease usually
affects the skin and
peripheral nerves but has
a wide range of possible
clinical manifestations.
Leprosy is caused by a
bacillus, Mycobacterium
leprae, that multiplies very
slowly and mainly affects
the skin, nerves, and
mucous membranes.
Necrotizing
Fasciitis (Flesh
eating bacteria)
Streptococcus
pyogenes
II. Viruses (from Latin word for “poison”)
A. What is a Virus?
1. Very small (need electron microscope to
see)
2. Core of DNA or RNA surrounded by protein
coat (capsid) with surface receptors (to
recognize the cell they want to attack)
a. Protein coat called capsid
(proteins enable virus to enter
host cell)
b. Once inside, viral gene
takes over
Herpes virus
B. Viral Infection- most viruses very specific (e.g.
bacteriophage-infects bacteria)
1. Lytic Infection- virus enters a cell and makes
copies of itself, and causes the cell to burst (cell
lyses)
2. Lysogenic Infection- a virus embeds it’s DNA
into the DNA of the host cell and is replicated along
with the host cell’s DNA
a. Lysogenic viruses do not lyse the host cell right
away
b. Eventually, several factors will activate DNA of
virus to begin synthesizing new virus particles
C. Viruses and Disease- cause polio, measles,
AIDS, mumps, influenza, yellow fever, rabies,
common cold, etc.
Influenza
Ebolavirus
virus
Small pox
1. Vaccines- used to prevent viral
infections- when injected into body,
stimulates the immune system (take out
DNA so WBC learns to recognize virus)
2. retroviruses- contain RNA as
genetic information (e.g. HIV,
hantaviruses)
HIV is an example of a retrovirus,
which contains RNA as its
genetic material. Retroviruses
get their name because their
genetic information is first copied
backward from RNA to DNA
3. Prions- stands for “Protein infectious particles”
Protein only- no DNA or RNA. Mad cause “Mad Cow
Disease” . Attack the brain.
Prions may cause
several infectious
diseases, including
mad cow disease and
scrapie (infectious
disease in sheep).
Experiments suggest
disease caused by
protein segments
found in brain
C. Are Viruses Alive? Not considered to be alive.
Lack certain characteristics of life.
Living things…..
•Are made up of units called cells
•Reproduce
•Are based on universal genetic code
•Grow and develop
•Obtain and use materials and energy
•Respond to their environment
•Maintain stable internal environment
•Taken as group, living things change over time
Chapter 19
Bacteria and Viruses
The structure in the figure represents a(an)
a.
virus.
b.
archaebacterium.
c.
methanogen.
d.
eubacterium.
The structure in the figure represents a(an)
a.
virus.
b.
archaebacterium.
c.
methanogen.
d.
eubacterium.
The figure below shows how prokaryotes can be
identified by
a.
the composition of their cell walls.
b.
their reaction to the Gram stain.
c.
their cell shapes.
d.
their methods for obtaining energy.
The figure below shows how prokaryotes can be
identified by
a.
the composition of their cell walls.
b.
their reaction to the Gram stain.
c.
their cell shapes.
d.
their methods for obtaining energy.
Which structures in the figure below is a cocci?
a.
A
b.
B
c.
C
d.
none of the above
Which structures in the figure below is a cocci?
a.
A
b.
B
c.
C
d.
none of the above
Bacilli, cocci, and spirilla refer to common
a.
Gram stains.
b.
shapes of prokaryotes.
c.
methods of prokaryotic movement.
d.
ways that prokaryotes obtain energy.
Bacilli, cocci, and spirilla refer to common
a.
Gram stains.
b.
shapes of prokaryotes.
c.
methods of prokaryotic movement.
d.
ways that prokaryotes obtain energy.
Which of the following are factors used to identify
prokaryotes?
a.
cell shape
b.
the way prokaryotes move
c.
the way prokaryotes obtain energy
d.
all of the above
Which of the following are factors used to identify
prokaryotes?
a.
cell shape
b.
the way prokaryotes move
c.
the way prokaryotes obtain energy
d.
all of the above
Unlike photoautotrophs, chemoautotrophs obtain
energy
a.
directly from the sun.
b.
directly from inorganic molecules.
c.
indirectly from organic molecules.
d.
indirectly from other organisms.
Unlike photoautotrophs, chemoautotrophs obtain
energy
a.
directly from the sun.
b.
directly from inorganic molecules.
c.
indirectly from organic molecules.
d.
indirectly from other organisms.
Most prokaryotes are
a.
heterotrophs.
b.
photoautotrophs.
c.
chemoautotrophs.
d.
photoheterotrophs.
Most prokaryotes are
a.
heterotrophs.
b.
photoautotrophs.
c.
chemoautotrophs.
d.
photoheterotrophs.
A method called Gram staining is used to tell
a.
what shape a prokaryote has.
b.
how a prokaryote obtains energy.
c.
what kind of cell wall a prokaryote has.
d.
whether a prokaryote has flagella or not.
A method called Gram staining is used to tell
a.
what shape a prokaryote has.
b.
how a prokaryote obtains energy.
c.
what kind of cell wall a prokaryote ha
d.
whether a prokaryote has flagella or not.
As decomposers, bacteria
a.
fix nitrogen.
b.
carry out photosynthesis.
c.
fight off viruses.
d.
recycle nutrients.
As decomposers, bacteria
a.
fix nitrogen.
b.
carry out photosynthesis.
c.
fight off viruses.
d.
recycle nutrients.
In which of the following places are you most likely
to find nitrogen-fixing bacteria?
a.
the atmosphere
b.
lakes and streams
c.
the roots of soybean plants
d.
a bag of nitrogen fertilizer
In which of the following places are you most likely
to find nitrogen-fixing bacteria?
a.
the atmosphere
b.
lakes and streams
c.
the roots of soybean plants
d.
a bag of nitrogen fertilizer
Food poisoning is an example of bacteria
a.
releasing toxins that make you sick.
b.
breaking down the body's tissues.
c.
resisting antibiotics.
d.
going through the lytic cycle.
Food poisoning is an example of bacteria
a.
releasing toxins that make you sick.
b.
breaking down the body's tissues.
c.
resisting antibiotics.
d.
going through the lytic cycle.
The few bacteria that cause disease are called
a.
viruses.
b.
pathogens.
c.
endospores.
d.
antibiotics.
The few bacteria that cause disease are called
a.
viruses.
b.
pathogens.
c.
endospores.
d.
antibiotics.
Which of the following diseases is NOT caused by
bacteria?
a.
tooth decay
b.
tuberculosis
c.
AIDS
d.
Salmonella food poisoning
Which of the following diseases is NOT caused by
bacteria?
a.
tooth decay
b.
tuberculosis
c.
AIDS
d.
Salmonella food poisoning
Bacteria are used to make which of the following
foods?
a.
cheese
b.
yogurt
c.
pickles
d.
all of the above
Bacteria are used to make which of the following
foods?
a.
cheese
b.
yogurt
c.
pickles
d.
all of the above
Food that is stored in your refrigerator will keep
longer because the bacteria that spoil food
a.
die at low temperatures.
b.
grow more slowly at low temperatures.
c.
require light to live.
d.
grow more slowly in the dark.
Food that is stored in your refrigerator will keep
longer because the bacteria that spoil food
a.
die at low temperatures.
b.
grow more slowly at low temperature
c.
require light to live.
d.
grow more slowly in the dark.
Which of the following is a characteristic of bacteria
that is key to keeping them under control?
a.
Most bacteria cannot survive high
temperatures for long periods.
b.
Most bacteria are resistant to harmful
chemicals.
c.
Most bacteria form endospores when
subjected to harsh conditions.
d.
Most bacteria do not attack human foods.
Which of the following is a characteristic of bacteria
that is key to keeping them under control?
a.
Most bacteria cannot survive high
temperatures for long periods.
b.
Most bacteria are resistant to harmful
chemicals.
c.
Most bacteria form endospores when
subjected to harsh conditions.
d.
Most bacteria do not attack human foods.
Which of the following is NOT a form of
sterilization?
a.
refrigeration
b.
boiling
c.
chemical disinfection
d.
frying
Which of the following is NOT a form of
sterilization?
a.
refrigeration
b.
boiling
c.
chemical disinfection
d.
frying
A virus's outer protein coat is called a
a.
DNA core.
b.
capsid.
c.
bacteriophage.
d.
tail sheath.
A virus's outer protein coat is called a
a.
DNA core.
b.
capsid.
c.
bacteriophage.
d.
tail sheath.
All viruses are made of proteins and
a.
nucleic acids.
b.
prophages.
c.
bacteriophages.
d.
endospores.
All viruses are made of proteins and
a.
nucleic acids.
b.
prophages.
c.
bacteriophages.
d.
endospores.
A viral capsid functions to
a.
bind the virus to the surface of a host cell.
b.
transcribe viral genes.
c.
force a host cell to make copies of the virus.
d.
destroy a host cell.
A viral capsid functions to
a.
bind the virus to the surface of a host cell.
b.
transcribe viral genes.
c.
force a host cell to make copies of the virus.
d.
destroy a host cell.
A lytic infection concludes with the
a.
embedding of viral DNA into the host cell's
DNA .
b.
production of a prophage.
c.
bursting of the host cell.
d.
production of messenger RNA.
A lytic infection concludes with the
a.
embedding of viral DNA into the host cell's
DNA .
b.
production of a prophage.
c.
bursting of the host cell.
d.
production of messenger RNA.
Bacteriophages infect
a.
other viruses.
b.
bacteria only.
c.
any available host cell.
d.
cells undergoing the lytic cycle.
Bacteriophages infect
a.
other viruses.
b.
bacteria only.
c.
any available host cell.
d.
cells undergoing the lytic cycle.
Unlike lytic viruses, lysogenic viruses do not
a.
inject their genetic material into the host cell.
b.
enter the lytic cycle.
c.
lyse the host cell right away.
d.
infect host cells.
Unlike lytic viruses, lysogenic viruses do not
a.
inject their genetic material into the host cell.
b.
enter the lytic cycle.
c.
lyse the host cell right away.
d.
infect host cells.
Viruses cause infection by
a.
producing toxins that harm the body.
b.
reproducing independently inside the body.
c.
forming endospores in the body.
d.
entering body cells and replicating.
Viruses cause infection by
a.
producing toxins that harm the body.
b.
reproducing independently inside the body.
c.
forming endospores in the body.
d.
entering body cells and replicating.