Download F5 Metabolism of Microbes - Mr Hartan`s Science Class

F5 Metabolism of Microbes
Terminology Review
Nutrition: The means by which organisms obtain the
energy they require, and a source of carbon for the
organic compounds they need.
Metabolism: the sum total of all chemical reactions in
the body.
*Prokaryotes can be divided into four
major categories (depending on their
mode of nutrition).*
F.5.1 Define the terms photoautotroph,
photoheterotroph, chemoautotroph,
and chemoheterotroph.
F.5.2 State one example of a each.
Photoautotroph
 Photoautotrophs are organisms that use light energy to
generate ATP and produce organic compounds (from inorganic
substances).
 Organisms carry out photosynthesis to acquire energy.
 They provide nutrition for all other forms of live (apart from
other photo/chemoautotrophs).
 Include plants, algae, some protists, and some bacteria
(cyanobacteria).
 Photoautotrophs contain the pigment molecule, chlorophyll
(and can therefore use light to make glucose).
 Cyanobacteria have been present on the Earth for about 3.4
billion years and are though to be the source of most of the
oxygen gas in the atmosphere.
Anabaena sperica
Anabaena is found in fresh-water
habitats and is an example of a freeliving, nitrogen-fixing bacterium.
Photoheterotroph
 Photoheterotrophs are organisms that use light energy to
generate ATP. They obtain organic compounds from other
organisms.
 When growing photosynthetically, they use light energy to
make glucose (anabolism). These organisms can also convert
to heterotrophic metabolism in order to break down glucose
for energy/ATP (catabolism).
 Rhodobacter is a purple, non-sulfur bacterium found in mud,
lake water and sewage (click below).
Chemoautotroph
 Chemoautotrophs are organisms that use energy from
chemical reactions to generate ATP. These organisms
produce organic compounds from inorganic substances.
 Archaea are often chemoautotrophs, although some
Eubacteria will fall into this category as well.
 Nitrosomonas and Nitrobacter release energy from the
oxidation of nitrites to nitrates, playing a role in the nitrogen
cycle.
Chemoheterotroph
 Chemoheterotrophs are organisms that use energy from
chemical reactions to generate ATP. Organic compounds are
obtained from other organisms.
 Most microbes are in this category. Many of these organisms
decompose organic matter, enabling the recycling of nutrients.
 E. coli is one of a huge number of chemoheterotrophs. E. coli
can be found in the human gut (fermenting sugars).
F.5.4 Compare photoautotrophs with photo
heterotrophs in terms of energy sources and
carbon sources. (see Figure 18.5)
 Photoautotrophs, such as the cyanobacterium, Anabaena, and
photoheterotrophs such as the purple, non-sulfur bacterium,
Rhodospirillum are:
 Both prokaryotic and, therefore, do not contain
chloroplasts.
 Contain photopigment molecules like chlorophyll a
(cyanobacteria) and bacteriochlorophyll (Rhodospirillum)
that harness light energy from the sun.
 These photopigments are found in the mesosomes of the
bacteria (infoldings of the cell membrane).
Energy Source
Photoautotroph
(cyanobacterium Anabaena)
Photoheterotrophs
(purple, non-sulfur
bacteria Rhodospirillum)
• Light energy is used to obtain
electrons from water.
• Light energy is also used to
generate ATP from ADP.
• Respiration is aerobic.
•
•
•
Carbon Sources
•
Carbon dioxide is reduced to
carbohydrate.
Water + Carbon Dioxide + Light →
Carbohydrate + Oxygen gas
•
Light energy to remove
electrons from organic
molecules.
Light energy is also used to
generate ATP from ADP.
Respiration is anaerobic.
A variety of sources
(organic or amino acids)
are reduced to
carbohydrate.
F.4.5 Compare chemoautotrophs with
chemoheterotrophs in terms of energy
sources and carbon sources.
 Chemoautotrophs (chemosynthetic bacteria), like all autotrophs,
use an external energy source to synthesize carbohydrates from
carbon dioxide.
 Use carbon dioxide as a raw material for making organic
compounds but maintain their energy by oxidizing inorganic
chemicals such as ammonia, nitrites and nitrates.
 Found growing in the absence of light.
 Nitrosomonas and Nitrobacter are examples of economically
important chemoautotrophs.
 Chemoheterotrophs: ‘Chemical other feeders.’ Obtain their carbon
atoms and energy from organic compounds. Heterotrophic
bacteria may be: (1) predators, eating other microorganisms; (2)
decomposers; (3) parasites; and (4) mutualistic organisms.
Chemoautotrophs
(Nitrosomonas)
•
Energy Source
•
•
Carbon Source
Chemoheterotrophs
(Azotobacter-aerobic
and Clostridiumanaerobic)
Inorganic chemical
reactions catalyzed as the
source of energy for the
synthesis of carbohydrate.
Respiration is the source
of ATP for metabolism.
•
Carbon dioxide is reduced
to carbohydrate.
•
Carbon Dioxide + Water +
Energy (inorganic chemicals)
→ Carbohydrate + Oxygen
Gas.
•
Complex organic
molecules taken into the
cell.
Respiration is the source
of ATP for metabolism.
Complex organic
molecules taken into the
cell.
F.5.5 Draw and label a diagram of a
filamentious cyanobacterium (Anabaena)
 Make sure you can label the photosynthetic cell and the
heterocyst of Anabaena. What is the function of the
photosynthetic cell and heterocyst?
F.5.6 Explain the use of bacteria in the
bioremediation of soil and water.
Examples should include selenium, solvents and pesticides in soil,
and oil spills in water.
 Bacterial Bioremediation of the environment is the process of
exploiting microorganisms in the removal of pollutants from the
environment.
 Bioremediation is a process that uses microorganisms, fungi, green
plants and their enzymes to return the natural environment altered
by contaminants to its original state. The enzymes in the bacteria
are used to break down the contaminants so they can be filtered
out. An example of bioremediation is selenium pollution. Microbes
are used to absorb selenium ions and oxidize them into metallic
selenium which is less toxic. Another example is solvent pollution in
which microbes de-chlorinate solvents in anaerobic conditions
producing less toxic wastes. The bacteria Dehalococcoides
ethenogenes breaks down chlorinated solvents in soil.