Download The Nitrogen Cycle - IISME Community Site

Name __________________ Period _____ Date _________
Lesson 1: Introduction to Soil Microbiology and the Nitrogen Cycle
Purpose:

To learn the main differences between the domains
Archaea and Bacteria

To learn what roles archaea and bacteria play in the
nitrogen cycle
Procedure:

Follow along with the powerpoint presentation and fill in the
missing notes
Day 2 - Soil Biology
There are 3 Domains in Biological Taxonomy:
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•
•
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Bacteria
Prokaryote – single celled
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•
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Eukaryota
Generally, multi-cellular organisms are
Protists
VALERY LYNN, IISME 2011
– Plants, Animals, Fungi,
Name __________________ Period _____ Date _________
•
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Cells contain membrane-bound
Double stranded linear DNA
Archaea
•
Archaea are prokaryotes (single-celled) that were once classified as a type of
bacteria.
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At first, scientists found them only in
springs, acid waters and salt lakes.
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But techniques in DNA sequencing have shown that they are
environments, like hot
•Genetic analysis of ribosomal RNA reveals that Archaea are different from
, even though they may look alike.
How are Archaea different from Bacteria?

Unlike Bacteria -
Different Cell Membranes
Archaea – Contains
linkages
Bacteria and Eukaryotes –
linkages
VALERY LYNN, IISME 2011
Name __________________ Period _____ Date _________
But, like Bacteria, Archaea have:
1.
2.
3.
4.
Bacteria and Archaea in Soil and Water
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Both Bacteria and Archaea have been found in soil and water (including the ocean) all
over the world.
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Most scientists use DNA techniques to determine their presence in an environment.
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Bacteria and Archaea in Soil and Water
Research has shown that Bacteria and Archaea are involved in a number of processes
that are crucial for the environment.
•One such process is:
The Nitrogen Cycle!!!
Of all nutrients, nitrogen often has the greatest effect on plant growth
•Nitrogen is a component for:
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–
–
–
VALERY LYNN, IISME 2011
Name __________________ Period _____ Date _________
Nitrogen composes 80% of the atmosphere and yet,
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Plants can suffer from nitrogen deficiencies.
Take a minute and discuss with your lab partners how this could be possible.
Have someone in your group write down a plausible answer that you all agree on and
share with the class before going on.
Write here:
Plants are Finicky!
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
Did you figure it out?
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Here’s another one!
Discuss with your group and write down ways that atmospheric nitrogen (N2) could
be converted to ammonium (NH4+), or nitrate (N3- ).
VALERY LYNN, IISME 2011
Name __________________ Period _____ Date _________
Write here:
Soil Microbes!
Look what they can do…
Atmosphere
N2
N2
Atmosphere
Soil
N2
Nitrogen-fixing
bacteria/archaea
Denitrifying
bacteria/archaea
H+
Nitrate and
nitrogenous
organic
compounds
exported in
xylem to
shoot system
(From soil)
Soil
+
NH4
NH3
(ammonia)
–
+
NH4
(ammonium)
Nitrifying
bacteria/archaea
NO3
(nitrate)
Ammonifying
bacteria/archaea
Organic
material (humus)
Figure 37.9
VALERY LYNN, IISME 2011
Root
Name __________________ Period _____ Date _________
The Nitrogen Cycle
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Nitrogen-fixing bacteria/archaea
– Nitrogen gas (N2)
Ammonia (NH3)
+
– (Add H from the soil and you’ve got (NH4+))
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Ammonifying bacteria/archaea
–Organic Material
Ammonium (NH4+)
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Nitrifying bacteria/archaea
– Ammonium (NH4+) Nitrate (NO3-)
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Denitrifying bacteria/archaea
–Nitrate (NO3-)
Nitrogen gas (N2)
Each of these reactions are catalyzed by a different enzyme
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Nitrogen-fixing bacteria/archaea
– Nitrogen gas (N2)
Ammonia (NH3)
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Ammonifying bacteria/archaea
–Organic Material
Ammonium (NH4+)
•
Nitrifying bacteria/archaea
– Ammonium (NH4+) Nitrate (NO3-)
•
Denitrifying bacteria/archaea
–Nitrate (NO3-)
Nitrogen gas (N2)
VALERY LYNN, IISME 2011