Transcript Organic Compounds

Essentials of Anatomy & Physiology, 4th Edition
Martini / Bartholomew
2
The Chemical Level
of Organization
PowerPoint® Lecture Outlines
prepared by Alan Magid, Duke University
Slides 1 to 74
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Matter: Atoms and Molecules
Atoms
• Smallest unit of
an element
• Subatomic
particles
• Protons: (+)
charge
• Neutrons:
neutral
• Electrons: (-)
charge
Figure 2-1
Matter: Atoms and Molecules
Structure of an atom
• Nucleus
• Protons
• Neutrons
• Electron Shell
Figure 2-2(b)
Matter: Atoms and Molecules
Structure of atom
• Atomic number
• Equals number of protons
• Atomic mass
• Equals protons + neutrons
• Isotopes of element
• Reflects number of neutrons
• Atomic weight
• Averages isotope abundance
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Matter: Atoms and Molecules
Structure of atom
• Electrons surround nucleus
• Electrons organized in shells
• The outer shell determines
chemical properties
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Matter: Atoms and Molecules
Atoms and Electron Shells
Figure 2-3
Matter: Atoms and Molecules
Key Note
All matter is composed of atoms
in various combinations. Their
interactions establish the
foundations of physiology at the
cellular level.
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Matter: Atoms and Molecules
Chemical Bonds and Compounds
•
•
•
•
Atoms bond in chemical reactions
Reactions transfer electrons
Electrons are gained, lost, or shared
Molecules or compounds result
• Compounds contain several
elements
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Matter: Atoms and Molecules
Ionic Bonds
• Atoms gain or lose electrons
• Charged atoms are ions
• Ions bear (+) or (-) charge
• Cations have (+) charge
• Anions have (-) charge
• Cations and anions attract
• Ions form bonds
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Matter: Atoms and Molecules
Ionic Bonding
Figure 2-4(a)
Matter: Atoms and Molecules
Sodium chloride crystal
Figure 2-4(b)
Matter: Atoms and Molecules
Table 2-2
Matter: Atoms and Molecules
Covalent bonds
• Some atoms share electrons
• Shared electrons complete outer shell
• Sharing atoms bond covalently
• Single covalent bond
• One shared electron
• Double covalent bond
• Two shared electrons
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Matter: Atoms and Molecules
Covalent Bonds
Figure 2-5
Matter: Atoms and Molecules
Nonpolar and Polar Covalent Bonds
• Equal electron sharing
• Nonpolar covalent bonds
• Example: carbon-carbon bonds
• Non-equal electron sharing
• Polar covalent bonds
• Example: oxygen-hydrogen bonds
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Matter: Atoms and Molecules
Hydrogen bonds
• Weak attractive force
• Between 2 neighboring atoms
• A polar-bonded hydrogen, and
• A polar-bonded oxygen or
nitrogen
• For example, between water
molecules
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Matter: Atoms and Molecules
Hydrogen Bonds
Figure 2-6
Chemical Notation
A chemical “shorthand”
• Simplified descriptions of:
• Compounds
• Structures
• Reactions
• Ions
• Abbreviations of elements
• Abbreviations of molecules
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Chemical Reactions
Metabolism
All the chemical reactions in
the body
• Consumes reactants
• Produces products
• Breaks or makes chemical
bonds between atoms
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Chemical Reactions
Basic Energy Concepts
• Work—movement or change in
matter’s physical structure
• E.g., running, synthesis
• Energy—ability to do work
• Kinetic energy
• Potential energy
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Chemical Reactions
Basic Energy Concepts (continued)
• Potential energy—stored energy
• E.g., leopard lurks in a tree
• Kinetic energy—energy of movement
• E.g., leopard pounces on prey
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Chemical Reactions
3 types of reactions
• Decomposition—breaks
molecule into smaller pieces
• Synthesis—assembles smaller
pieces into larger one
• Exchange—shuffles pieces
between molecules
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Chemical Reactions
Decomposition Reactions
• In chemical notation:
• AB
A+B
• Releases covalent bond energy
• Hydrolysis—Decomposition
reaction with H•OH
• E.g., food digestion
• Catabolism—Sum of all the
body’s decomposition reactions
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Chemical Reactions
Synthesis Reactions
• In chemical notation:
• A+B
AB
• Absorbs energy
• Formation of new bonds
• Dehydration synthesis
• Removal of H•OH between molecules
• Anabolism—Sum of the body’s
synthesis reactions
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Chemical Reactions
Exchange Reaction
• In chemical notation:
• AB + CD
AC + BD
• Decomposition and synthesis
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Chemical Reactions
Reversible Reactions
• A+B
AB
• Equilibrium—Condition when
the forward and reverse
reactions occur at the same
rate
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Chemical Reactions
Key Note
When energy is exchanged,
heat is produced. Heat raises
local temperatures, but cells
cannot capture it or use it to
perform work.
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Enzymes and Reactions
Activation Energy
Quantity of energy needed
to start a chemical reaction
• Catalysts reduce activation
energy to speed reaction
• Enzymes catalyze cellular
reactions
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Enzymes and Reactions
Enzymes and Activation Energy
Figure 2-7
Enzymes and Reactions
Exergonic—Reactions that
release energy
• E.g., decomposition reactions
Endergonic—Reactions that
consume energy
• E.g., synthesis reactions
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Inorganic Compounds
Nutrients
Essential elements and molecules
obtained from the diet
Metabolites
Molecules synthesized or broken
down by chemical reactions inside
the body
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Inorganic Compounds
Inorganic
Smaller molecules such as water
and oxygen that lack carbon and
hydrogen
Organic
Larger molecules such as sugars,
proteins, and fats composed largely
of carbon and hydrogen
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Inorganic Compounds
Carbon Dioxide (CO2)
• Gas produced by cellular
metabolism and released into the
atmosphere via the lungs
Oxygen (O2)
• Atmospheric gas consumed by
cells in order to produce energy
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Inorganic Compounds
Water and its properties
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•
•
•
Most important body chemical
Excellent solvent
High heat capacity
Essential chemical reactant
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Inorganic Compounds
Water Dissociates Ionic Bonds
Figure 2-8
Inorganic Compounds
Key Note
Water accounts for most of your body
weight. Proteins, key components of
cells, and nucleic acids, which control
cells, work only in solution.
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Inorganic Compounds
Inorganic Acids and Bases
• Acid—Releases hydrogen ions
(H+) into solution
• E.g., HCl
H+ + Cl-
• Base—Removes hydrogen ions
from solution
• E.g., NaOH + H+
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Na+ + H•0H
Inorganic Compounds
pH
A measure of hydrogen ion
concentration in a solution
• Neutral solution—pH = 7
• Acidic solution—pH below 7
• Basic solution—pH above 7
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Inorganic Compounds
pH and Hydrogen Ion Concentration
Figure 2-9
Inorganic Compounds
Buffers
• Maintain pH within normal
limits (pH 7.35 to pH 7.45)
• Release hydrogen ions if
body fluid is too basic
• Absorb hydrogen ions if body
fluid is too acidic
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Inorganic Compounds
Salt
An ionic compound not containing
H+ or OH-
•Salts are electrolytes
•Electrolytes dissociate in water
• E.g., NaCl
Na+ + Cl-
•Electrolytes carry electrical currents
in the body
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Organic Compounds
Organic Compounds
• Contain carbon, hydrogen,
and usually oxygen
• Important classes of organic
compounds include:
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
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Organic Compounds
Carbohydrates
• Most important energy source for
metabolism
• Three major types
• Monosaccharides (E.g., glucose)
• Disaccharides (E.g., sucrose)
• Polysaccharides (E.g., glycogen)
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Organic Compounds
Glucose
Figure 2-10
Organic Compounds
Formation and Breakdown of Complex Sugars
Figure 2-11 (a), (b)
Organic Compounds
Formation of Glycogen
Figure 2-11(c)
Organic Compounds
Table 2-4
Organic Compounds
Lipids
• Water-insoluble
• Four important classes
• Fatty acids
• Fats
• Steroids
• Phospholipids
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Organic Compounds
Table 2-5
Organic Compounds
Fatty Acids
Figure 2-12
Organic Compounds
Triglycerides—
Formed by three
fatty acid molecules
bonding to a
glycerol molecule
Figure 2-13
Organic Compounds
Cholesterol
• Building block for steroid hormones
• Component of cell membranes
Figure 2-14
Organic Compounds
Phospholipids
• Most abundant
membrane lipid
• Diglyceride
• Two fatty acids + glycerol
• Water-soluble and waterinsoluble parts
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Organic Compounds
A Phospholipid
Molecule
Figure 2-15
Organic Compounds
Proteins
• Most abundant organic
component in human body
• About 100,000 different proteins
• Contain carbon, nitrogen,
oxygen, hydrogen, and a bit of
sulfur
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Organic Compounds
Proteins play vital roles
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Support
Movement
Transport
Buffering
Regulation
Defense
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Organic Compounds
Proteins are
built from
amino acids
Figure 2-16(a)
Organic Compounds
Peptide bonds join
amino acids into
long strings
Figure 2-16(b)
Organic Compounds
Protein Structure
Figure 2-17
Organic Compounds
Protein Structure
• “R” groups interact with their
neighbors and with solvent
• Amino acid chain folds and
twists into complex shape
• Final shape determines
function
• High fever distorts shape
• Distorted proteins don’t work
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Organic Compounds
Enzyme Function
• Substrates (reactants) bind to
active site on enzyme surface
• Binding lowers activation
energy needed for reaction
• Substrates react to form
product
• Product is released from
enzyme surface
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Organic Compounds
Enzyme function made simple
Figure 2-18
PLAY
Enzymes
Organic Compounds
Nucleic Acids
• Large molecules
• Built from atoms of C, H, O, N, and P
(What are these elements?)
• Store and process molecular
information
• Two classes of nucleic acid
• DNA (deoxyribonucleic acid)
• RNA (ribonucleic acid)
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Organic Compounds
The Structure of
Nucleic Acids
Figure 2-19ab
Organic Compounds
The Structure of Nucleic Acids
Figure 2-19cd
Organic Compounds
Structure of Nucleic Acids
• Nucleotides contain a sugar,
a phosphate, and a base
• Sugar-phosphate bonds link
nucleotides in long strands
• Hydrogen bonds hold two
DNA strands in a double helix
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High-Energy Compounds
• Catabolism releases energy
• Cells store energy in highenergy compounds
• High-energy compounds drive
endergonic reactions
• ATP is the most important highenergy compound in cells
• ATP keeps cells alive!
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High-Energy Compounds
Structure of ATP
Figure 2-20
ATP
Energy
from
cellular
catabolism
Energy
released
for cellular
activities
ADP
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Figure 2-21
1 of 5
ATP
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Figure 2-21
2 of 5
ATP
Energy
released
for cellular
activities
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Figure 2-21
3 of 5
ATP
Energy
released
for cellular
activities
ADP
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Figure 2-21
4 of 5
ATP
Energy
from
cellular
catabolism
Energy
released
for cellular
activities
ADP
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Figure 2-21
5 of 5
Summary of Body Chemistry
Organic Chemical Building Blocks
Figure 2-22