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POWERPOINT® LECTURE SLIDE PRESENTATION
by ZARA OAKES, MS, The University of Texas at Austin
Additional text by Jessica Padilla exclusively for Physiology at ECC
UNIT 1
2
Molecular Interactions
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
DEE UNGLAUB SILVERTHORN
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FOURTH EDITION
About this Chapter
 Atoms, ions, and molecules (self review)
 Types of chemical bonds (self review)
 Biomolecules
 Solutions, concentrations, and pH
 Water Properties
 Protein interactions
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Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Types of Biomolecules
 All four types are composed of either monomers or
covalently linked polymers. The first three provide
energy to the body.
 Monomers are connected by dehydration reactions to
create polymers
 Polymers are broken down into monomers by
hydrolysis reactions
The four groups of biomolecules (organic
macromolecules) are:
 Carbohydrates
 Lipids
 Proteins
 Nucleotides and nucleic acids
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 Most macromolecules are polymers
 Polymers are made by stringing together many smaller
molecules called monomers
 Cells link monomers by a process called dehydration
synthesis
 In this process water is removed to unite the two units
and form a polymer.
Short polymer
Monomer
Longer polymer
(a) Dehydration synthesis of a polymer
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Figure 3.7A
Polymers broken to monomers
 Organisms also have to break down macromolecules
 Cells do this by a process called hydrolysis
 In hydrolysis a water molecule is used to split a bond
between two monomers to reduce the size of the polymer.
(b) Hydrolysis of a polymer
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Figure 3.7B
Carbohydrates
 Most abundant
 Carbon
 Hydrogen
 Oxygen
 Simple
 Monosaccharides (glucose, ribose)
 Complex
 Polysaccharides (glycogen, starch)
 Monomer linked to form polymers by a glycosilic
bond
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Carbohydrates
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Figure 2-7 (1 of 3)
Carbohydrates
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Figure 2-7 (3 of 3)
Fun Facts
 Americans consume an
average of 140 pounds of
sugar per person per year
 Cellulose, found in
plant cell walls, is the
most abundant organic
compound on Earth
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Lipids
 Carbon and hydrogen (little oxygen)
 Structurally diverse
 Eicosanoids
 Steroids
 Phospholipids
 Triglycerides
 Glycerol
 Fatty acid chains
 Saturated
 Unsaturated
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High Energy Fuel Source
 Larger hydrocarbons
 Are the main
molecules in the
gasoline we burn
in our cars
 The hydrocarbons
of fat molecules
provide energy for
our bodies
Figure 3.4
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Lipids and Lipid-Related Molecules
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Figure 2-8 (1 of 5)
Proteins
 Amino acids
 Essential
 Amino group
 Acid group
 Protein structure
 Polypeptides
 Primary through quaternary
 Most versatile
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 The four types of proteins
(d) Transport
proteins
(b) Storage
proteins
(a) Structural proteins
(c) Contractile proteins
Figure 3.18
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Levels of Organization in Protein Molecules
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Figure 2-9 (1 of 6)
Protein Shape
 Proteins have four levels of structure
Hydrogen bond
Pleated sheet
Polypeptide
(single subunit)
Amino acid
(a) Primary structure
Complete
protein,
with four
polypeptide
subunits
Hydrogen bond
Alpha helix
(b) Secondary
structure
(c) Tertiary
structure
(d) Quaternary structure
Figure 3.23
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Proteins
 Various types of bonds interact to create different types of
proteins. The types of bonds that shape the protein affect
the structure.
 Fibrous
 Globular
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Figure 2-10
Nucleic Acids
 Composition
 Base, sugar, and phosphate(s)
 Transmit and store
 Information (genetic code)
 Energy transfer molecules
 ATP, cAMP,
NAD, and FAD
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Nucleotides, DNA, and RNA
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Aqueous Solutions
 Aqueous
 Water-based
 Solution
 Solute dissolves in solvent
 Solubility
 Ease of dissolving
 Hydrophobic
 Hydrophilic
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Aqueous Solubility
Sodium chloride dissolves in water
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Figure 2-14
Water properties
 Molecular structure
 Hydrogen bond-the high amount of hydrogen bond in
water give it properties no found in other substances.
It makes it less dense as a solid and give a high
specific heat.
 Surface tension- results from cohesion and adhesion
 Cohesion- water molecules stick together
 Adhesion-water molecules stick to surfaces
 Biological Process
Water can absorb and store large amounts of heat while only
changing a few degrees in temperature thus allowing it to
regulate heat in the body.
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Water properties
 These
illustrate the
properties of
water that
result from
hydrogen
bonding.
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Hydrogen Ion Concentration (pH)-self review
 Acid
 Contributes H+ to solution
 Base
 Decreases H+ in solution
 pH
 - log [H+]
 Buffer minimizes changes of pH
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Hydrogen Ion Concentration (pH)
pH scale
Mechanisms
in the body
closely
regulate blood
ph to protect
from the
harmful
effects of
going beyond
the range.
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Figure 2-15
Protein Interactions
 Human Proteomics Initiative- determine all the
types of proteins in the body.
 Protein Solubility- the degree to how water
soluble a protein is determines influences is role in
the body
 Insoluble – create supportive structures like collagen
and keratin
 Soluble- carry out chemical reactions and interact
with molecules
 Seven categories- these include enzymes,
membrane transporters, signal molecules, receptors,
binding and regulatory proteins, and antibodies.
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Protein Interactions
 Binding- when proteins binds a conformation change called induce fit
occurs. The bind success depends on:
 Selectivity- protiens bind specific molecules
 Ligand- generic name for molecules that bind and interact
 Substrate- ligands that bind enzymes and membrane transporter
 Binding site- area where ligand attaches and forms reversible
or irreversible bonds
 Specificity- the ability of a protein to bind a certainligand
 Affinity- degree to which a protein is attracted to a ligand.
A high disassociation constant indicates low affinity.
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Selective Binding: Induced-Fit Model
The induced-fit model of protein-ligand binding
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Figure 2-16
Factors that affect protein binding
 Isoforms- proteins with similar function but different affinities for the same
ligand. Ex- fetal vs adult hemoglobin
 Activation – some inactive proteins undergo a physical alteration to become
active- like protein hormones and enzymes
 Cofactors – must bind to protein to enhance affinity to ligand, usually it’s a
functional group or ion.
 Lysis – cleaving a protein section to activate it.
 Modulators – influences binding or activity of a protein
 Chemical modulators – bind covalently or non-covalently to alter binding
or activity by decreasing or increasing it.
 Antagonists – decreases activity by blocking binding site
 Competitive inhibitors – reversible antagonists that competitively bind and
can be displaced
 Allosteric modulators -reversible antagonists that competitively bind but
can not be displaced
 Covalent modulators - bind and alter properties to activate or inactivateex. penicillin
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Modulators Alter Binding or Activity
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Factors that Affect Affinity
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Figure 2-18
Competitive Inhibition
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Figure 2-19
Allosteric Modulation
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Figure 2-20a
Allosteric Modulation
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Figure 2-20b
Physical Regulators
 Temperature- each protein has a adequate temperature for it’s
function. Outside of the range it may be denatured of inactivated.
 pH- each protein has a adequate temperature for it’s function. Outside of
the range it may be denatured of inactivated.
 Concentration of protein –amounts in body vary over time to
control physiological processes
 Up-regulation – programmed production of protein
 Down regulation – programmed removal of protein
 Concentration of ligand – determines the magnitude of the
reponse if the protein concentration is the same.
 Reaction rates – speed up as ligand concentration increases up
until saturation is reached.
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Summary
 Atoms in review
 Four types of chemical bonds
 Four kinds of biomolecules
 Aqueous solutions and pH
 Proteins in focus
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