Download Survey of the Phyla-ProkaryoteON

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Archaea and BacteriaThe PROKARYOTES
As late as 1977, all prokaryotes were put into one single
kingdom called Monera. Taxonomists no longer accept
that concept. Some prokaryotes are more closely related
to eukaryotes than other prokaryotes. Most taxonomists
now accept the concept of super kingdoms or domains.
Two of the three domains are prokaryotes
General information
I. Three common shapes (cocci, bacilli, spirilla)
II. Small 0.5-5 mm
Which of the following is true?
A) There are three domains in one
kingdom.
B) The Moneran Kingdom is recognized
by taxonomists as the kingdom for
single celled eukaryotes
C) Archaea contains prokaryotic cells.
D) Bacteria contains both prokaryotic
cells and single celled eukaryotic cells.
ANS: C
The Domains Bacteria and Archaea
contains only prokaryotic cells. The
prokaryotes in the Archaea Domain
are more closely related to
eukaryotes. All eukaryotic celled
organisms are in the Domain Eukarya.
III. Bacterial cell wall made of carbohydrate polymers that are
connected by polypeptide chains (peptidoglycan). Grampositive bacteria (stain purple with Gram-stain) have cell
walls with just the peptidoglycan wall connected to
plasma membrane. Gram-negative bacteria (stain pink)
have peptidoglycan wall sandwiched between two
membranes. The cell wall of Archae are made from
polysaccharides and certain proteins but NOT
peptidoglycans.
Some prokaryotes have a second layer outside the cell wall.
-Capsule-sticky layer of carbohydrates or proteins.
-Fimbriae-protein appendages that allows the prokaryote to
attach to surfaces
Which of the following has a
peptidoglycan cell wall?
A) a prokaryote in the Archaea Domain
B) plant cells
C) fungal cells
D) a prokaryote in the Bacteria Domain
ANS: D
The cells walls in the Bacteria Domain
is composed of peptidoglycan which is
carbohydrate connected by small
polypeptide chains.
IV. Nucloid region-area where circular DNA chromosome is
located. Chromosome lacks histones (some prokaryotes in
Archae do). May also contain smaller circular pieces of DNA
or plasmids.
V. Ribosomes are smaller than cytoplasmic eukaryotic
ribosomes.
VI. Some prokaryotes have infoldings of the plasma membrane
similar to cristae and some photosynthetic prokaryotes have
internal membranes similar to thylakoid membranes.
VII. Some prokaryotic cells have flagella. The flagellum is
different from eukaryotic cells. It is a solid core of protein
(1/10th width). It is driven by a system of rings in the cell wall.
ATP pumps transports H+ out cell. When the H+ diffuse back in
it powers the flagella which rotates like a helicopter rotor.
Flagellated prokaryotes can exhibit taxis moving toward or
away chemicals, nutrients or oxygen.
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Which of the following is true?
A) Prokaryotes have well defined
organelles
B) Prokaryotes have no internal
membranes
C) Some prokaryotes have membranes
around the DNA
D) Some prokaryotes have internal
membranes for respiration or
photosynthesis.
ANS: D
Some prokaryotes have some
membranes for respiration ( like the
cristae) or for pigments for
photosynthesis (like the thylakoid)
Reproduction-Reproduction is via binary fission. Bacteria
can obtain genetic variation via conjugation, transformation, or
transduction
Conjugation-(Lederberg & Tatum)
1. Conjugation-Certain bacteria that have been mutated, would
need additonal nutrients in their media in order to grow.
Bacteria without these mutations will grow on minimal media.
E.Coli had been mutated and 2 different strains were found
#1- needed methonie and vitamin biotin but could make its own
leucine and threonine.
#2-needed threonine and leucine but could not make its own
methonine and vitamin biotin. When these two types were
mixed, there emerged some new cells that had the ability to
grow on minimal media. Conclusion: There had to be some
exchange of genes or recombination of genes.
What causes the movement of
prokaryotic flagella?
A) Passive diffusion
B) Active transport
C) Facilitated diffusion
D) Osmosis
ANS: B
Both active transport and passive
diffusion are incorporated to make the
flagella move. H+ ions are pumped out
of the cell by ATP pumps (active
transport) and as the H+ ion flow back
into the cell (passive diffusion), the
energy is used to move the flagella.
Recombination has occurred because the new cells can grow
on minimal media. It was also discovered that in addition to
the main chromosome, prokaryotic cells contained smaller
circles of DNA (plasmids) which also contained genes.
The arrow points to a plasmid in a lysed E.Coli
cell which is then magnified. This plasmid
contains genes that makes the cell resistant to the
antibiotic tetracycline.
Plasmids replicate
independent of the
main chromosome.
These plasmids are
being replicated.
In order for conjugation to occur there must be 2
different mating types F+ (male) and F- (female). F+
males have a plasmid (sex factor) which is replicated.
When a F+ and F- meet, they form a cytoplasmic
bridge or pilus. The copied F+ plasmid is transferred
to F- making it F+.
The population never completely is
converted to F+ because
1. F- can undergo bacterial
reproduction (fission) faster than F+
can conjugate.
2. The formation of the pilus, allows
for cetain viruses to attack, and they
only attack F+ cells.
Conjugating bacteria with
the pilli connecting the
cells to one another to
exchange DNA.
Some F+ plasmids are inserted into
the main chromosome becoming Hfr
(high frequency recombinants).
When Hfr conjugates with F-, the
entire main chromosome is replicated.
However during transfer only part of the
chromosome is transferred.
The gene for Hfr is usually at the end of
the chromosome, so that the receiving cell
F- will stay an F-. The longer the pilus
stays together, the more genes transferred.
Which of the following mating types
have the ability to conjugate and
produce a cell with genetic variation
A) F- x FB) F+ x F+
C) Hfr x FD) F+ x F-
ANS: D
Two mating types can undergo
conjugation F- (female) x F+ (male).
The F+ has the sex plasmid which is
transferred to the F- female. The
second mating type is F- (female) x
Hfr (male). The Hfr cell has the sex
plasmid integrated into the main
circular chromosome.
Autonomous plasmids-Plasmids that never integrate themselves into
the chromosome. They may carry genes that include antibiotic
resistance or a virulence factor. Plasmids have the ability to
replicate themselves so that a prokaryotic cell may have 1,000 to
3,000 copies of it.
2. Transformation- Involves prokaryotic cells taking up extraneous
DNA from the environment. Genetic engineering uses this technique
in transforming bacteria and using engineered plasmids.
3.Transduction- Bacterial cells obtaining DNA
via a viral vector.
The rapid reproduction, mutations, and genetic
recombination allows for a great variety in their metabolic
pathways. In fact, every possible mode of nutrition in the
living world is found in prokaryotes:
-Photoautotroph-does photosynthesis and uses CO2 as its
carbon source
-Chemoautotroph-uses CO2 to make organic compounds on
its own and uses chemicals like H2S and NH3 for energy
instead of light
-Photoheterotroph-uses light for energy but obtains carbon
from an organic source.
-Chemoheterotroph-uses organic compounds for both an
energy source and carbon source. Most are decomposers or
pathogens that break organic compounds down.
What is the process called in which
prokaryotic cells take up extraneous
DNA from the environment?
A) conjugation
B) transformation
C) transduction
D) binary fission
ANS: B
Transformation is the process called in
which prokaryotic cells take up
extraneous DNA from the
environment. Conjugation involves two
prokaryotic cells with different mating
types. Transduction involves a viral
vector, and binary fission is the
asexual reproduction of prokaryotic
cells.
Types of cell respiration
-Obligate aeorbes must use oxygen for cell respiration or will
die without it
-Obligate anaerobe- oxygen is not used for cell respiration
and the cell is actually poisoned by it.
-Faculative anaerobes-can use oxygen when present or do
fermentation if oxygen is not present.
Nitrogen fixation
Some prokaryotes have the ability to “fix” atmospheric
nitrogen (N2) into ammonia NH3. Then the ammonia can be
converted into nitrates and nitrites. The nitrogen compounds
then can be converted into amino acids. Important part of
nitrogen cycle. Some prokaryotes live in symbiotic
relationships with this pathway. The root nodules of legumes
contain nitrogen fixing bacteria.
Types of photosynthesis-Some prokaryotes are
photosynthetic. There are two types of photosynthesis in
prokaryotes
Type I that gives off O2 as a by product.
Contains photosystem I and II like higher plants
Contains chlorophyll a like higher plants
Splits water
6 CO2 + 6 H2O -> C6H12O6 + 6 O2
Type II that does not give off O2 as a by product.
Contains only photosystem I
Contains bacteriochloropyll
Splits hydrogen sulfide
CO2 + 2H2S -> (CH2O)n + 2 S
How would you classify a prokaryotic
cell that can uses CO2 to make organic
compounds on its own and uses
chemicals like H2S and NH3 for energy
instead of light?
A) photoautotroph
B) photoheterotroph
C) chemoheterotroph
D) chemoautotroph
ANS:
D
-Photoautotroph-does photosynthesis and uses
CO2 as its carbon source
-Chemoautotroph-uses CO2 to make organic
compounds on its own and uses chemicals like
H2S and NH3 for energy instead of light
-Photoheterotroph-uses light for energy but
obtains carbon from an organic source.
-Chemoheterotroph-uses organic compounds
for both an energy source and carbon source.
Most are decomposers or pathogens that
break organic compounds down.
Domain Bacteria-Supergroups
1. Proteobacteria-Gram negative with 5 subgroups. Metabolic
diverse photoautotrophs, chemoautotrophs, and
heterotrophs. Some are aerobic while others are anaerobes.
2. Chlamydias-Obligate pararsites only live in other cells.
Major cause blindness.
3. Spirochetes-Spiraled shaped with internal like flagellum.
Caused syphilis and Lyme disease.
4. Cyanobacteria-does type I photosynthesis generating
oxygen. Some cells specialized (heterocysts) for fixing
nitrogen
5. Gram-positive bacteria-Metabolic diverse group. Some
obligate parasites, some secrete antibiotics.
Domain Archaea-Supergroups can live in extreme
environments and more normal environments. More
closely related to eukaryotes than other prokaryote
1. Extreme halophiles can tolerates saline enviroments.
Tolerance from slightly saline to over 9% saline (Marine
enviroments is 3.5% saline).
2. Exterme thermophiles can tolerate very hot environments.
Proteins are very stable at this temperature and DNA
remains as a double helix. One strain of Geogemma
barossii can tolerate temperature of over 121o C.
3. Methanogens- use CO2 to oxidize H2 to make methane gas.
Obligate anaerobes. Found under ice, swamps, guts of
cattle, and termites.
4. Moderate environment-many prokaryotes from the Domain
Archaea are live in moderate environments.
Prokaryotes in the environment
Symbiotic relationshipsMutualistic- Ex-certain bacteria in your gut are important to
the digestive system and the bacteria benefit by the food that
is provided to them.
Commensalistic-Ex There a many bacteria living on the
surface of the skin. They do not harm or provide any benefit
to the epidermal cells. The epidermal cells provide oils, food
and a habitat to live
Parasitic-Ex-Some prokaryotes are pathogens (cause
disease). Many bacterial diseases can be treated with
antibiotics which are compounds that destroy prokaryotic
cells but not eukaryotic cells. Usually the disease is caused
by either an exotoxin (made and secreted by the prokaryote)
or endotoxin (made by the prokaryote and only released if the
prokaryote dies). Botulism is caused by an exotoxin made by
Clostridium botulinum and typhoid fever is caused by an
endotoxin made by Salmonella typhi.
What is the source of the nitrogen
used by prokaryotic cells that can do
nitrogen fixation?
A) the air in the form of N2
B) the soil in the form of nitrates
C) the water in the form of ammonia
D) the soil in the form of nitrates
ANS: A
The source of the nitrogen for
nitrogen fixation comes from the N2 in
the atmosphere. It is reduced to
ammonia and then later oxidized to
either nitrates or nitrates. Plants can
use the ammonia, nitrates and nitrites
as a source for nitrogen.
Prokaryotes are the most dominant organisms on this earth.
Without them, life as we know it would not exist. They are
important in
-decomposers
-nutrient recycling
-nitrogen fixation
-food industry
-symbiosis
-medicine
-producers in food chains.
This chart compares and
contrast three different
domains. It is based on the
sequencing of the rRNA
found in the small ribosomal
subunit. The Archaea
prokaryotes are more
closely related to
eukaryotes than to the
Bacteria prokaryotes.
There are certain bacteria that live in
the digestive system and have the
ability to make vitamin D. The
digestive system provides nutrients
for the bacteria. This relationship
could most precisely be classified as
A) symbiotic
B) parasitic
C) commensalistic
D) mutualistic
ANS: D
Mutualism is the most precise answer
because both organisms benefit. It is
a form of symbiosis but mutualism is
the most precise. Commensalism and
parasitism is a form of symbiosis.
Which of the following would not be a
classification for a cell that has the
ability to take in carbon dioxide and
reduce it to methane gas?
A) prokaryote
B) bacteria
C) methanogen
D) Archaea
ANS: B
Methanogens belong in the domain
Archaea and the domain Bacteria.
Cells in both of these domains are
prokaryotes.