From Chemistry To Energy To Life

1
From Chemistry To Energy To Life

• Chapter 4

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Chemistry and the environment

• Chemistry is central to environmental science
• Carbon dioxide and climate change
• Sulfur dioxide and acid rain
• Pesticides and public health
• Nitrogen and wastewater treatment
• Ozone and its atmospheric depletion

3
Bioremediation

• One application of chemistry is in
  bioremediation, the use of plants or animals to
  clean up pollution.

Rice University student Marc Burrell has
researched how to get plants to take up toxic
lead from contaminated soil.
From The Science behind the Stories
4
Atoms and elements

• An element is a fundamental type of chemical
  substance.
• Elements are composed of atoms.
• Each atom has a certain number of
• protons ( charge)
• electrons ( charge)
• neutrons (no charge)

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Atoms and elements

• 92 elements occur in nature, each with its
  characteristic number of protons, neutrons, and
  electrons.

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Chemical symbols

• Each element is abbreviated with a chemical
  symbol
• H hydrogen
• C carbon
• N nitrogen
• O oxygen
• P phosphorus
• Cl chlorine
• Fe iron

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Most abundant elements
8
Isotopes

• Isotopes are alternate versions of elements,
  which differ in mass by having a different number
  of neutrons.
• Carbon-14 has two extra neutrons beyond normal
  carbons 6.

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Using isotopes in environmental science

• Scientists have used isotopes to date ancient
  materials, reconstruct past climate, study the
  diet of animals, examine lifestyles of
  prehistoric humans, and track migrating birds and
  butterflies.

From The Science behind the Stories
10
Molecules, compounds, and bonds

• Ions electrically charged atoms or combinations
  of atoms
• Molecules combinations of two or more atoms
• Compounds molecules consisting of multiple
  elements
• Atoms are held together by bonds
• covalent bond uncharged atoms sharing
  electrons (CO2)
• ionic bond charged atoms held together
  by electrical attraction (NaCl)

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Water is a unique compound

• Hydrogen bonds give water properties that make it
  a vital molecule for life
• Is cohesive
• Resists temperature change
• Ice insulates
• Dissolves many chemicals

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Why ice floats on water

• Stable hydrogen bonds in ice make it less dense
  than water, with its unstable hydrogen bonds.

ice
This allows ice to cover water bodies and protect
them from freezing a good thing for life in the
water.
water
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Water, the universal solvent

• Water dissolves many chemicals.Salt
  (NaCl) in seawater is broken up into sodium (Na)
  and chloride (Cl) ions.

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Acidity

• In an aqueous solution,
• If H concentration is greater than OH
  concentration,
• then solution is acidic.
• If OH is greater than H ,
• then solution is basic.

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pH scale

• pH scale measures acidity and basicity.
• Pure water 7
• Acids lt 7
• Bases gt 7

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Organic compounds

• Consist of carbon atoms and, generally, hydrogen
  atoms
• Joined by covalent bonds
• May include other elements
• Highly diverse C can form many elaborate
  molecules
• Vitally important to life

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Hydrocarbons

• C and H only major type of organic
  compoundMixtures of hydrocarbons make
  up fossil fuels.

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Macromolecules

• Large molecules essential for life
• Proteins
• Nucleic acids
• Carbohydrates
• Lipids
• The first three are polymers, long chains of
  repeated molecules.

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Proteins

• Consist of chains of amino acids fold into
  complex shapes
• For structure, energy, immune system, hormones,
  enzymes

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Carbohydrates

• Complex carbohydrates consist of chains of
  sugars.
• For energy, also structural (cellulose, chitin)

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Lipids

• Do not dissolve in water
• Fats and oils
• Phospholipids
• Waxes
• Steroids

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Nucleic acids

• DNA and RNA
• Encode genetic information and pass it on from
  generation to generation
• DNA double-stranded chain (double helix)
• RNA single-stranded chain

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Nucleic acids

• Paired strands of nucleotides make up DNAs
  double helix.

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Genes and heredity

• Genes, functional stretches of DNA, code for the
  synthesis of proteins.

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Cells

• Basic unit of organismal organization
  compartmentalize macromolecules and organelles

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Energy

• Can change position, physical composition, or
  temperature of matter
• Potential energy energy of position
• (water held behind a dam)
• Kinetic energy energy of movement
• (rushing water released from a dam)

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Potential and kinetic energy

• Potential energy stored in food is converted to
  kinetic energy when we exercise.

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Laws of thermodynamics

• First Law Energy can change form, but cannot be
  created or lost.
• Second Law Energy will tend to progress from a
  more-ordered state to a less-ordered state
  (increase in entropy).

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Increase in entropy

• Burning firewood demonstrates the second law of
  thermodynamics.

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Energy from the sun

• Energy from the sun powers most living
  systems.
• Visible light is only part of the suns
  electromagnetic radiation.

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Autotrophs and photosynthesis

• The suns energy is used by autotrophic
  organisms, or primary producers (e.g., plants),
  to manufacture food.
• Photosynthesis turns light energy from the sun
  into chemical energy that organisms can use.

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Photosynthesis

• In the presence of chlorophyll and
  sunlight,Water and carbon dioxide
• are converted to
• sugars and oxygen.

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Photosynthesis
6 CO2 12 H2O energy from sun gt C6H1
2O6 (sugar) 6 O2 6 H2O
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Streamlined
6 CO2 6 H2O energy from sun gt C6H
12O6 (sugar) 6 O2
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Respiration and heterotrophs

• Organisms use stored energy via respiration,
  which splits sugar molecules to release chemical
  energy.
• This occurs in autotrophs and in the heterotrophs
  (animals, fungi, most microbes) that eat them.

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Respiration

• The equation for respiration is the exact
  opposite of the equation for photosynthesis.

C6H12O6 (sugar) 6 O2 gt 6 CO2 6
H2O chemical energy
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Energy sources besides the sun

• Geothermal energy comes from deep underground
  radiation in Earths core heats the inside of the
  planet and rises to the surface (driving plate
  tectonics, volcanoes, etc.).
• Gravitational pull of the moon creates tidal
  energy.

Geyser powered by geothermal energy
38
Chemosynthesis

• Some organisms and communities live without
  sunlight and are powered by chemosynthesis.

6 CO2 6 H2O chemical energy from
H2S gt C6H12O6 (sugar) 6 O2
sulfates
(H2 S hydrogen sulfide)
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Hydrothermal vent communities

• Such communities include those at hydrothermal
  vents deep in the ocean. Recently discovered
  bizarre organisms.

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Origin of life on Earth

• Early Earth was a hostile place life had a
  challenging
• start.

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Fossil record

• Fossil imprint in rock of a dead organism
• The fossil record teaches us much of what we know
  of life on the planet over the past 3.5 billion
  years.

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Fossil record

• The fossil record shows that
• Species today are a tiny fraction of all that
  ever lived.
• Earlier organisms evolved into later ones.
• The number of species has increased through
  time.
• Episodes of mass extinction have occurred.
• Eukaryotes are only 600 million years old.

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History of life

• By studying present-day organisms or their genes,
  we can infer relationships among organisms and
  decipher lifes history.
• Lifes complete phylogeny is the tree of life.

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How did life originate?
Several hypotheses are competing

• Heterotrophic hypothesis (primordial soup)
  interactions in early soup of organic chemicals
• Extraterrestrial hypothesis (seeds from space)
  microbes from elsewhere arrived on meteorites
• Chemoautotrophic hypothesis (life from the deep)
  first life from deep-sea hydrothermal vents

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Conclusion

• Carbon-based life has flourished on Earth for
  over 3 billion years.
• Scientists are trying to understand its origin.
• Deciphering the origins of life requires
  understanding energy, energy flow, and chemistry.

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Conclusion

• Energy and chemistry are tied to nearly every
  important process in environmental science.
• Chemistry can also be a tool for finding
  solutions to environmental problems.
• Knowledge of chemistry is relevant to
  agriculture, water resource management, energy
  policy, toxicology, and climate change.

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QUESTION Review

• Which of the following is a heterotroph?
• a. Pine tree
• b. Photosynthetic algae
• c. Squid
• d. Hydrogen sulfide

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QUESTION Review

• The second law of thermodynamics states that?
• a. Energy cannot be created or destroyed
• b. Things tend to move toward a less-ordered
  state
• c. Matter tends to remain stable
• d. Potential and kinetic energy are
  interchangeable

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QUESTION Review

• Which of these does the fossil record NOT
  demonstrate?
• a. There have been mass extinction episodes.
• b. Most organisms that ever lived are now
  extinct.
• c. Animals originated before plants, and plants
  before bacteria.
• d. Numbers of species have increased through
  time.

50
QUESTION Weighing the Issues

• If there was an oil spill on your campus, would
  you recommend bioremediation?
• a. Yes, because it is environmentally most
  desirable.
• b. No, because it is less tested than traditional
  methods.
• c. It depends. (on what factors?)

51
QUESTION Interpreting Graphs and Data

• A molecule of the hydrocarbon ethane contains?

• a. 2 carbon atoms and 6 hydrogen atoms
• b. 2 carbon molecules and 6 hydrogen enzymes
• c. Carbon and hydrogen DNA
• d. Eight different isotopes

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QUESTION Interpreting Graphs and Data

• Which is listed from most acidic to most basic?
• a. Ammonia, baking soda, lemon juice
• b. Stomach acid, soft soap, HCl
• c. Acid rain, NaOH, pure water
• d. HCl, acid rain, ammonia

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QUESTION Viewpoints

• How do you think life on Earth began?
• a. With a mix of organic compounds in a
  primordial soup on Earths surface
• b. With the entrance of microbes from other
  planets on meteorites falling to Earth
• c. In deep-sea hydrothermal vents