Download 3.2 The Organic Chemistry of Life

CHAPTER
3
The Physical
Science of the
Environment
Lecture by
David Serrano,
Broward College
PERIODIC TABLE
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3.1 Chemistry of the Environment
• Atoms–basic unit of matter
– Made of three particles
• Protons
– In central nucleus, has positive charge
• Neutrons
– In central nucleus, electrically neutral
• Electrons
– Surrounds nucleus, has negative charge
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© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Elements are made of one type of atom
• Number of protons determine
Characteristics and name
• 92 naturally occurring elements
• Represented by a symbol
– H, hydrogen
– C, carbon
– O, oxygen
– N, nitrogen
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3.1 Chemistry of the Environment
• Isotopes
– Same number of protons, different number of
neutrons
• Carbon has 6 protons, may have 6, 7, or 8
neutrons
• Different weights useful in science
• Radioactive isotopes
• Some unstable, decay at steady rate, emit
radiation
• Half-life: time it takes for half of the atom to decay
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© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Ions
– Atom gained or lost an electron
– Results in overall charge
• Gained electron = negative charge
• Lost electron = positive charge
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3.1 Chemistry of the Environment
• Molecules
– Two or more atoms combined
• Oxygen (O2), nitrogen (N2)
• Compounds
– Molecules made from more than one element
• Carbon dioxide (CO2), water (H2O)
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3.1 Chemistry of the Environment
• Chemical bonds hold molecules together
– Ionic bond
• Strong bond
• Electron transferred between atoms
• Termed ionic compounds or salts
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© 2013 Pearson Education, Inc.
3.1 Chemistry of the Environment
• Water–important to life
– Polar molecule
• Forms dipole bonds with other water molecules
– Gives water unique properties, stability
• An excellent solvent
– Many biological functions use water as solvent.
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3.1 Chemistry of the Environment
• Water–important to life
– Acids and bases
• Water dissociates into H+ and OH–
• Chemicals (acid/base) may shift amounts
– Shift measured by pH scale
• pH of solution affects biological functions
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Increasingly basic
(lower H+ concentration)
14 1.0 M NaOH
Increasingly acidic
(greater H+ concentration)
Neutral
[H+] =
[OH–]
13
Ammonia
Household ammonia
12
11
Milk of magnesia
10
Baking soda
9
8 Seawater
Human blood
7 Pure water
Milk
6
5
4
3
2
1
Tomatoes
Wine
Vinegar, colas
Lemon juice
Stomach acid
0 pH scale
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Neutral
[H+] =
[OH–]
Increasingly acidic
(greater H+ concentration)
0
1
pH scale
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2
3
4
5
6
7
Increasingly basic
(lower H+ concentration)
8
9
10
11
12
13
14
3.2 The Organic Chemistry of Life
• Organic molecules
– Carbon atom covalently bonded to hydrogen
and other atoms
– Primary structural and function component of
life
– Range in size
– Inorganic molecules not made of carbon and
hydrogen
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3.2 The Organic Chemistry of Life
• Organic molecules–types
– Hydrocarbons
• Only made of carbon and hydrogen
– Carbohydrates
• Made of carbon, hydrogen, oxygen
• Sugars, (CH2O)n, with n between 3 and 7
• Glucose (C6H12O6) the basic form of energy for
most organisms
• Sugars known as saccharides
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3.2 The Organic Chemistry of Life
• Organic molecules–types
– Lipids
• Long chains of carbon and hydrogen and a shorter
region with one to several oxygen molecules
– Fats and oils
– Nonpolar
– Lipids not water soluble
– Important energy storage
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3.2 The Organic Chemistry of Life
• Macromolecules
– Small organic molecule linked together
• Polymers
– Linked together in long chains
• Polysaccharides
– Polymers of simple sugars
• Starch
• Cellulose
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3.2 The Organic Chemistry of Life
• Macromolecules
– Proteins
• Polymers of amino acids
• 20 amino acids–same base structure
– Amino group (–NH2)
– Carboxylic acid group (–COOH)
• Proteins made of chains of 100 to 1,000+ amino
acids
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3.2 The Organic Chemistry of Life
• Macromolecules
– Proteins
– Fold to particular shapes yielding function
– Structural or functional
– May act as catalysts
• Termed enzymes
• Almost all biological reactions use enzymes
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3.2 The Organic Chemistry of Life
• Nucleic acids
– Polymers of nucleotides
• 5-carbon sugar, phosphate group, and nitrogenous
base
– Deoxyribonucleic acid (DNA)
• Hereditary material
• Traits coded in sequence of bases
– adenine (A), thymine (T), cytosine (C), and guanine (G)
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3.2 The Organic Chemistry of Life
• Nucleic acids
– Ribonucleic acid (RNA)
• Structure similar to DNA
• Protein synthesis
– Transcription
• DNA code to RNA
– Translation
• RNA code to protein
• Triplet sequences code for amino acids
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DNA
Replication
Transcription
RNA
Translation
Protein
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3.3 Energy and the Environment
• Energy
– Capacity to do work
• Work
– Force applied to an object over a distance
– Potential energy
• Stored energy
– Kinetic energy
• Energy in motion
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3.3 Energy and the Environment
• Laws of thermodynamics
– First law
• Energy can be neither created nor destroyed; can
be transformed
– Second law
• Energy transformations increase disorder
– Entropy
– Energy often lost as heat
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3.3 Energy and the Environment
• Forms of energy
• Four types important for ecosystems
– Electromagnetic radiation
• Energy moves as photons in waves
• Electromagnetic spectrum–entire range of
wavelengths
– Gamma rays, X-rays, visible light, radiation, infrared,
microwaves, radiowaves
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Energy sufficient to increase temperature
Energy sufficient to activate electrons
Visible
Light
100 nm
Infrared Rays
10 m
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Microwaves
1 mm
10 cm
Radio Waves
10 m
1 km
100 km
3.3 Energy and the Environment
• Forms of energy
• Four types important for ecosystems
– Heat
• Kinetic energy of molecules
• Temperature
– Average kinetic energy
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3.3 Energy and the Environment
• Forms of energy
• Four types important for ecosystems
– Heat can move in four ways
•
•
•
•
Conduction
Convection
Radiation
Latent heat transfer
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© 2013 Pearson Education, Inc.
3.3 Energy and the Environment
• Forms of energy
– Chemical energy
• Potential energy
• Breaking and forming of chemical bonds
– Photosynthesis assembles carbohydrates
– Potential energy in glucose bonds
– When needed, energy released by respiration
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© 2013 Pearson Education, Inc.
3.4 The Planet Earth in Context
• Formation of solar system
• Sun began forming 4.6 billion years ago
– The gases and dust not consumed by sun
became planets and other objects
• Planet-like objects
• Asteroids
• Comets
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Pluto and
Charon
Neptune
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Uranus
Saturn
Jupiter
Mars
Earth
Venus Mercury
Sun
3.5 Earth's Structure
• Earth's structure
– Core–mixture of nickel and iron
• Solid inner core
• Liquid outer core
• Currents in the liquid core produce magnetic field
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3.5 Earth's Structure
• Earth's structure
– Mantle
• Above core
• 70% of Earth's volume
• Rich in elements magnesium and silicon
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3.5 Earth's Structure
• Earth's structure
– Crust
• Thin surface layer of relatively light rock
• < 1% of Earth's volume
• Only part that directly interacts with living systems
– Lithosphere
• Crust and upper part of mantle that interacts with it
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Inner solid core
Outer core
Lower mantle
Upper mantle
Oceanic crust
Continental crust
Core radius: 3,480 km (2,160 mi)
Mantle radius: 2,900 km (1,800 mi)
Crust depth: 5–100 km (3–60 mi)
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3.5 Earth's Structure
– Tectonic plates meet at boundaries
• Transform fault boundaries
– Plates slide past
– Sites of earthquakes
– Divergent boundaries
• Plates spread apart
– Convergent boundaries
• Plates come together
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Transforming boundary
C
A
Oceanic crust
Movement of
oceanic plate
Rising magma
Diverging plate
boundary
Magma forms
Ocean plate is
subducted
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B
3.6 Earth's Atmosphere
• Earth has gravity to hold atmosphere
• Earth's unique atmosphere supports life
– Composition of gases
•
•
•
•
78% nitrogen
21 % oxygen
0.039% carbon dioxide
Water vapor
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© 2013 Pearson Education, Inc.
3.6 Earth's Atmosphere
• Layers of atmosphere
– Troposphere
• Lowest layer
• Life located here
• Temperature drops with elevation
– Stratosphere
• 11–48 km
• Temperature increases approaching ozone
• Ozone layer located here
– Protects life from ultraviolet radiation
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3.6 Earth's Atmosphere
• Layers of atmosphere
– Mesosphere
• Above stratosphere
• Air temperature drops again (173 ºC) at 90 km
– Thermosphere
•
•
•
•
Extends out to space
Above 150 km gas density so low no friction
International Space Station orbits here
Aurora occurs here
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3.7 Earth's Energy Budget, Weather, and
Climate
• Weather and climate
– Climate
• Long-term atmospheric conditions
– Temperature, humidity, average rainfall
– Weather
• Short-term variations local atmospheric conditions
– Thunderstorms
© 2013 Pearson Education, Inc.
© 2013 Pearson Education, Inc.