BIO EVENTS
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Two more lectures remain!
Optional, 30-point final quiz will occur in Quizzes in D2L.
Covers the entire course.
Has 17, short-answer/short-essay questions.
Is open book, but limited to 50 minutes.
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"The plural of anecdote is not data." Tom Frieden, former Director of the U.S. Centers for Disease Control talking about the risks of electronic cigarettes.
Anecdote = a short account of a particular incident or event, especially of an interesting or amusing nature. Data = a series of observations or measurements.
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Review of previous activities.
On-line (and upcoming) activities
Tracking nitrogen in the biosphere.
Assignment
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Last Event
Food security and sovereignty and energy transfer in food production.
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Important information in the Dropbox Feedback:
On-line activities, Event 15
CHAPTER 8: Ecology
Module 28: Communities*
Module 29: Ecosystems*
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* Module with quiz
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UNIT 3 The Cell
UNIT 4 Metabolism
UNIT 5 Cell Division
UNIT 6 Classical Genetics
UNIT 7 Evolution
UNIT 2 Introduction
to Chemistry
UNIT 8 Ecology
UNIT 1 Introduction
Biogeochemical Cycles
The processes that transfer chemical elements between biotic and abiotic components in an ecosystem.
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Water: Event 4
Carbon: Event 7
Biogeochemical Cycles
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life
Biogeochemical Cycles
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life
earth
Biogeochemical Cycles
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life
earth
elements/
molecules
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Biogeochemical Cycles
A
B
C
D
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Biogeochemical Cycles
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Event 4
Water cycle
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Global carbon cycle
Event 7
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93
Humans:
93% of weight
Mineral elements
Element %*
Magnesium 0.05
Potassium 0.25
Magnesium 0.05
Phosphorous 1.1
Calcium 1.4
Nitrogen
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3.0
* % of fresh weight
(55-65% water).
Mineral elements
Element %*
Sulfur 0.1
Phosphorous 0.2
Magnesium 0.2
Calcium 0.5
Potassium 1.0
Nitrogen 1.5
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Nitrogen
1.5
* % of dry weight. Mature plants 70-95% water.
Mineral elements = chemical element usu. other than carbon, hydrogen, oxygen, or nitrogen that is a constituent of plant or animal tissue and
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Why so much nitrogen?
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DNA molecule
nitrogen
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Proteins
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glycine
lycine
Amino acids
nitrogen
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chlorophyll
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chlorophyll a
nitrogen
Where does the nitrogen come from?
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Earth’s atmosphere is 78% nitrogen…
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= 78.1%
= 20.9%
N2 , N N
Earth’s
atmosphere
Nitrogen fixation is a process by which nitrogen (N2) in the atmosphere is converted into ammonia (NH3).[1] Atmospheric nitrogen or molecular nitrogen (N2) is relatively inert: it does not easily react with other chemicals to form new compounds. Fixation process free up the nitrogen atoms from their diatomic form (N2) to be used in other ways.
Nitrogen fixation, natural and synthetic, is essential for all forms of life because nitrogen is required to biosynthesize basic building blocks of plants, animals and other life forms, e.g., nucleotides for DNA and RNA and amino acids for proteins. Therefore nitrogen fixation is essential for agriculture and the manufacture of fertilizer. It is also an important process in the manufacture of explosives (e.g. gunpowder, dynamite, TNT, etc.). Nitrogen fixation occurs naturally in the air by means of lightning.[2] [3]
Nitrogen fixation also refers to other biological conversions of nitrogen, such as its conversion to nitrogen dioxide. Microorganisms that can fix nitrogen are prokaryotes (both bacteria and archaea, distributed throughout their respective kingdoms) called diazotrophs. Some higher plants, and some animals (termites), have formed associations (symbioses) with diazotrophs.
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Bacteria in soil
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A biogeochemical cycle:
The nitrogen cycle
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Nitrogen cycle
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nitrogen fixation
Nitrogen fixation and cycling
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N2 nitrogen-fixing NH3
Plants
Animals
Decomposers
bacteria
ammonia
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Nitrogen-fixing bacteria inside root nodules
N2
nitrogen-fixing
bacteria
NH3
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Symbiotic nitrogen fixation within root nodules occurs in many members of the bean family (Fabaceae)
Velvet mesquite
(Prosopis velutina)
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Free-living nitrogen-fixing bacteria
N2
nitrogen-fixing
bacteria
NH3
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N
N
N
N
nitrogenase
enzyme
nitrogen gas
H
H
H
N
H
H
H
N
H
N
N
H
H
H
H
H
N
N
H
H
H
H
H
H
N
N
nitrogenase
enzyme
ammonia
ATP
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Phosphorus cycle
Assignment, Part 1
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1. Briefly describe how microevolution differs from macroevolution.
Assignment, Part 2:
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2. Many scientists would argue that the enzyme nitrogenase may be the single most important enzyme on Earth.
Explain in a short paragraph the basis for this statement. Your answer should include discussion of what nitrogenase does and why this is so important.
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