Transcript Chapter 17 - myndrs.com

Chapter 17
Monerans
Or Prokaryotic Cells
What are monera?
• Remember from our classification notes
that one of the five kingdoms is the
kingdom monera.
• Consists of the smallest organisms on the
planet.
• They are mostly prokaryotic
– Meaning they don’t have a nucleus
Classification of Monerans:
(four phyla)
1. Eubacteria: “true” bacteria
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Contains the most number of species of all the
monera phyla
Usually referred to as bacteria
Consist of a cell wall made of complex
carbohydrates (protects bacterium from injury
Cell membrane surrounding cytoplasm (some have
two cell membranes)
Some have long whip-like flagella which protrude
from the membrane through the cell wall (used for
movement)
Different jobs: nitrogen fixers, photosynthetic, and
disease causers in other organisms
Classification of Monerans:
(four phyla)
2. Cyanobacteria: photosynthetic bacteria
– AKA blue-green algae –but now we only use
algae for eukaryotes
– Those that are blue-green in color contain a
blue pigment called phycocyanin and also
chlorophyll-a which is green.
– The presence of other pigments may
change the color to yellow, brown and even
red.
Classification of Monerans:
(four phyla)
– Contain membranes that carryout the light reactions
of photosynthesis.
• These membranes are quite different from and simpler than
chloroplasts in plant cells.
– Found throughout the world in fresh water and salt
water and on land
– Few species can survive in extremely hot water,
others can even grow on snow
– They are often the first species to recolonize after a
natural disaster –ex a volcanic eruption.
Classification of Monerans:
(four phyla)
3. Archaebacteria
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Includes organisms that live in extremely harsh
environments
Example: one group lives in oxygen-free
environments such as mud or digestive tracts of
animals. These are called methogens because they
produce methane gas
Other species live in extremely hot environments
such as hot springs which can reach almost the
boiling point of water.
Classification of Monerans:
(four phyla)
4. Prochlorobacteria
– Photosynthetic organisms that contain both
chlorophyll a and b
– More like the chloroplast of green plants
than to cyanobacteria.
– AKA prochlorophyta –phyta means plantsto emphasize this similarity.
– Only two species have been discovered.
Identifying Monerans
1. Cell Shape: there are three basic shapes
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Rods –called “bacilli”
Sphere – called “coccus”, like streptococcus which
causes strep throat
Spiral –called “spirilla”
2. Arranging themselves in a distinct way:
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some grow in colonies
others (like streptococcus) form large chains
others form large clumps or clusters.
Identifying Monerans
3. Cell walls
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some have a double membrane others have a
single
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Gram staining
4. Kinds of movement:
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propelled by one or more flagella
others lash, snake or spiral forwards
others glide slowly along a layer of slimelike
material that they secrete themselves.
Some do not move at all.
Identifying Monerans
5. How they obtain energy:
a. Autotrophs: can make their own food.
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Phototrophic autotrophs. Ex: cyanobacteria
and some photosynthetic eubacteria
Chemotrophic autotrophs: live in harsh
environments and obtain energy from inorganic
molecules (hydrogen sulfide, nitrites, sulfur and
iron)
Ex: Nitrosomonas –uses ammonia and oxygen to
produce energy
Identifying Monerans
b. Heterotrophs: need to get food from
other sources.
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Chemotrophic heterotrophs: take organic
molecules and then break them down. Ex:
salmonella from raw meat, which also release
poisons into the food they are eating—food
poisoning.
Phototrophic heterotrophs: use sunlight for
energy, but they also need organic compounds
for nutrition
Bacteria Growth and
Reproduction
Methods:
1. Binary Fission: the
equal division of a
bacteria into two daughter
cells
– Replicates its DNA and
divides in half
– Asexual reproduction
(no mixing of DNA)
– Ex: E.coli
Binary fission video
Bacteria Growth and
Reproduction
2. Conjugation: (fig 17-14)
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A form of sexual reproduction
(the exchanging of genetic
material)
A long bridge of protein forms
between and connects two
bacterial cells
Genetic info from one cell is
transferred to the other cell.
The new combinations of
genes enhances the genetic
diversity in that population of
bacteria. –enhancing the
chance of survival.
Bacterial conjugation
Bacterial Conjugation
Bacteria Growth and
Reproduction
3. Spore formation: Figure 17-15
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Asexual
Some produce an endospore (a thick internal wall
that encloses its DNA and a portion of its
cytoplasm).
This thing can remain dormant for months or even
years waiting for more favourable conditions for
growing.
When conditions are better the endospore will open
up and the bacterium will grow again.
Technically not reproduction but rather a
sophisticated defense system.
(Endo)spore formation
Quiz Next Class
• Differentiate between the three methods of
bacterial reproduction.
• Be sure to include
– the type of reproduction
• Sexual or asexual
– A brief description of each type
– What is happening with respect to the DNA
Importance of Monerans:
• We use products made by monerans
every day for example:
– Cheese
– Yogurt
– Buttermilk
– Sour cream
– Pickles
– Sauerkraut
– Vinegar from wine
Importance of Monerans:
• Bacteria are also used in industry for
example:
– One type can digest petroleum (useful in
cleaning up small oil spills)
– Some remove waste products and poisons
from water
– Others help mine minerals from the ground
– Synthesizing drugs and chemicals through
techniques of genetic engineering (i.e. insulin,
factor C, etc.)
Symbiotic relationships
• Bacteria form symbiotic relationships with other
organisms, that is both the bacteria and the
other organisms benefit from the relationship.
• For example our intestines are inhabited by
large numbers of bacteria, including E. coli.
(called “coli” because they were found in the
colon)
– Inside the intestines, the bacteria get a warm, safe
home, plenty of food, and free transportation.
– In turn, we get help in digesting are food and
production of vitamins that we cannot produce on our
own.
Symbiotic relationships
• Another example: Cows need bacteria to
digest cellulose (fiber) which is found in
grass and hay.
Bacteria in the Environment:
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Bacteria are necessary for three major
jobs that help maintain life as we
know it:
1. Nutrient Flow: Bacteria recycle and
decompose, or break down, dead
material
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Example: form the moment a tree dies, armies
of bacteria attack and digest the dead wood,
breaking it down into simpler substances.
The result is the tree nutrients are recycled,
enriching the soil in which it grew.
Bacteria in the Environment:
2. Sewage Decomposition:
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Humans take advantage of the ability of bacteria to
decompose material in the treatment of sewage.
Bacteria is added directly to waste water, and they
grow rapidly. As they grow, they break down the
complex compounds in the sewage into simpler
compounds.
This process produces purified water nitrogen gas
and carbon dioxide gas, and leftover products that
can be used as crop fertilizers.
Bacteria in the Environment:
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Nitrogen Fixation:
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All organisms on our planet are totally dependent on
monerans for nitrogen.
All green plants need nitrogen to make amino acids and
because animals eat plants, plant proteins are ultimately the
source of proteins for animals.
Our atmosphere is 80% nitrogen gas, but this form of nitrogen
is useless to plants
They require that nitrogen be “fixed” chemically in the form of
ammonia (NH3) and related nitrogen compounds.
Cyanobacteria and other monerans are the only
organisms that can fix nitrogen
Example: soybean plants and Rhizobium form a symbiotic
relationship to fix nitrogen
Bacteria and Disease:
• Some of the diseases caused by
pathogenic bacteria include:
– Diphtheria
– Tuberculosis
– Typhoid fever
– Tetanus
– Hansen disease
– Syphilis
– Cholera
Bacteria and Disease:
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Two general ways that bacteria cause
diseases:
1. They may damage the cells and tissues of the
infected organism directly by breaking down its
living cells to use for food
2. They release toxins that travel throughout the
body, interfering with the normal activity of the
host.
Bacteria and Disease:
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How to fight against bacterial
infections in the body:
1. stimulate the immune system with vaccines
2. a number of drugs
3. antibiotics
Bacteria and Disease:
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Methods of controlling bacteria:
1. Sterilization: Through great heat or
disinfectant chemicals
2. Food Processing: including refrigeration,
boiling, frying, or steaming. Placing food in
salt, vinegar