ch02 b.chemistry.mission
TRANSCRIPT
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Human Anatomy & PhysiologySEVENTH EDITION
Elaine N. MariebKatja Hoehn
PowerPoint® Lecture Slides prepared by Vince Austin, Bluegrass Technical and Community College
C H
A P
T E
R
2Chemistry Comes Alive
P A R T B
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Biochemistry
Organic compounds
Contain carbon, are covalently bonded, and are often large
Inorganic compounds
Do not contain carbon
Water, salts, and many acids and bases
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Properties of Water
High heat capacity – absorbs and releases large amounts of heat before changing temperature
High heat of vaporization – changing from a liquid to a gas requires large amounts of heat
Polar solvent properties – dissolves ionic substances, forms hydration layers around large charged molecules, and serves as the body’s major transport medium
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PLAYPLAY InterActive Physiology®: Fluid, Electrolyte, and Acid/Base Balance: Introduction to Body Fluids
Properties of Water
Reactivity – is an important part of hydrolysis and dehydration synthesis reactions
Cushioning – resilient cushion around certain body organs
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Salts
Inorganic compounds
Contain cations other than H+ and anions other than OH–
Are electrolytes; they conduct electrical currents
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Acids and Bases
Acids release H+ and are therefore proton donors
HCl H+ + Cl –
Bases release OH– and are proton acceptors
NaOH Na+ + OH–
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Acid-Base Concentration (pH)
Acidic solutions have higher H+ concentration and therefore a lower pH
Alkaline solutions have lower H+ concentration and therefore a higher pH
Neutral solutions have equal H+ and OH– concentrations
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Acid-Base Concentration (pH)
Acidic: pH 0–6.99
Basic: pH 7.01–14
Neutral: pH 7.00
Figure 2.13
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Buffers
Systems that resist abrupt and large swings in the pH of body fluids
Carbonic acid-bicarbonate system
Carbonic acid dissociates, reversibly releasing bicarbonate ions and protons
The chemical equilibrium between carbonic acid and bicarbonate resists pH changes in the blood
PLAYPLAY InterActive Physiology®: Fluid, Electrolyte, and Acid/Base Balance: Acid/Base Homeostasis
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Organic Compounds
Molecules unique to living systems contain carbon and hence are organic compounds
They include:
Carbohydrates
Lipids
Proteins
Nucleic Acids
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Carbohydrates
Contain carbon, hydrogen, and oxygen
Their major function is to supply a source of cellular food
Examples:
Monosaccharides or simple sugars
Figure 2.14a
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Carbohydrates
Disaccharides or double sugars
Figure 2.14b
PLAYPLAY Disaccharides
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Carbohydrates
Polysaccharides or polymers of simple sugars
Figure 2.14c
PLAYPLAY Polysaccharides
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Lipids
Contain C, H, and O, but the proportion of oxygen in lipids is less than in carbohydrates
Examples:
Neutral fats or triglycerides
Phospholipids
Steroids
Eicosanoids
PLAYPLAY Fats
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Neutral Fats (Triglycerides)
Composed of three fatty acids bonded to a glycerol molecule
Figure 2.15a
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Other Lipids
Phospholipids – modified triglycerides with two fatty acid groups and a phosphorus group
Figure 2.15b
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Other Lipids
Steroids – flat molecules with four interlocking hydrocarbon rings
Eicosanoids – 20-carbon fatty acids found in cell membranes
Figure 2.15c
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Representative Lipids Found in the Body
Neutral fats – found in subcutaneous tissue and around organs
Phospholipids – chief component of cell membranes
Steroids – cholesterol, bile salts, vitamin D, sex hormones, and adrenal cortical hormones
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Representative Lipids Found in the Body
Fat-soluble vitamins – vitamins A, E, and K
Eicosanoids – prostaglandins, leukotrienes, and thromboxanes
Lipoproteins – transport fatty acids and cholesterol in the bloodstream
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Amino Acids
Building blocks of protein, containing an amino group and a carboxyl group
Amino group NH2
Carboxyl groups COOH
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Amino Acids
Figure 2.16a–c
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Amino Acids
Figure 2.16d, e
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Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Amino acid Amino acid
Dehydrationsynthesis
HydrolysisDipeptide
Peptide bond
+N
H
H
C
R
H
O
N
H
H
C
R
CC
H
O H2O
H2O
N
H
H
C
R
C
H
O
N
H
C
R
C
H
O
OH OH OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Amino acid Amino acid
+N
H
H
C
R
H
O
N
H
H
C
R
CC
H
O
OH OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Amino acid Amino acid
Dehydrationsynthesis
+N
H
H
C
R
H
O
N
H
H
C
R
CC
H
O H2O
OH OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Amino acid Amino acid
Dehydrationsynthesis
Dipeptide
Peptide bond
+N
H
H
C
R
H
O
N
H
H
C
R
CC
H
O H2O
N
H
H
C
R
C
H
O
N
H
C
R
C
H
O
OH OH OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Dipeptide
Peptide bond
N
H
H
C
R
C
H
O
N
H
C
R
C
H
O
OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
HydrolysisDipeptide
Peptide bond
H2O
N
H
H
C
R
C
H
O
N
H
C
R
C
H
O
OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Amino acid Amino acidHydrolysis
Dipeptide
Peptide bond
+N
H
H
C
R
H
O
N
H
H
C
R
CC
H
O
H2O
N
H
H
C
R
C
H
O
N
H
C
R
C
H
O
OH OH OH
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Protein
Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds
Figure 2.17
Amino acid Amino acid
Dehydrationsynthesis
HydrolysisDipeptide
Peptide bond
+N
H
H
C
R
H
O
N
H
H
C
R
CC
H
O H2O
H2O
N
H
H
C
R
C
H
O
N
H
C
R
C
H
O
OH OH OH
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Structural Levels of Proteins
Primary – amino acid sequence
Secondary – alpha helices or beta pleated sheets
PLAYPLAY Chemistry of Life: Proteins: Secondary Structure
PLAYPLAY Chemistry of Life: Proteins: Primary Structure
PLAYPLAY Chemistry of Life: Introduction to Protein Structure
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Structural Levels of Proteins
Tertiary – superimposed folding of secondary structures
Quaternary – polypeptide chains linked together in a specific manner
PLAYPLAY Chemistry of Life: Proteins: Quaternary Structure
PLAYPLAY Chemistry of Life: Proteins: Tertiary Structure
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Structural Levels of Proteins
Figure 2.18a–c
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Structural Levels of Proteins
Figure 2.18b,d,e
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Fibrous and Globular Proteins
Fibrous proteins
Extended and strand-like proteins
Examples: keratin, elastin, collagen, and certain contractile fibers
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Fibrous and Globular Proteins
Globular proteins
Compact, spherical proteins with tertiary and quaternary structures
Examples: antibodies, hormones, and enzymes
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Protein Denuaturation
Reversible unfolding of proteins due to drops in pH and/or increased temperature
Figure 2.19a
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Protein Denuaturation
Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes
Figure 2.19b
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Molecular Chaperones (Chaperonins)
Help other proteins to achieve their functional three-dimensional shape
Maintain folding integrity
Assist in translocation of proteins across membranes
Promote the breakdown of damaged or denatured proteins
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Characteristics of Enzymes
Most are globular proteins that act as biological catalysts
Holoenzymes consist of an apoenzyme (protein) and a cofactor (usually an ion)
Enzymes are chemically specific
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Characteristics of Enzymes
Frequently named for the type of reaction they catalyze
Enzyme names usually end in -ase
Lower activation energy
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Characteristics of Enzymes
Figure 2.20
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Mechanism of Enzyme Action
Enzyme binds with substrate
Product is formed at a lower activation energy
Product is released
PLAYPLAY How Enzymes Work
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.21
Active siteAmino acids
Enzyme (E)Enzyme-substratecomplex (E-S)
Internal rearrangementsleading to catalysis
Dipeptide product (P)
Free enzyme (E)
Substrates (S)
Peptide bond
H2O
+
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.21
Active siteAmino acids
Enzyme (E)Enzyme-substratecomplex (E-S)
Substrates (S)
H2O
+
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.21
Active siteAmino acids
Enzyme (E)Enzyme-substratecomplex (E-S)
Internal rearrangementsleading to catalysis
Substrates (S)
H2O
+
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.21
Active siteAmino acids
Enzyme (E)Enzyme-substratecomplex (E-S)
Internal rearrangementsleading to catalysis
Dipeptide product (P)
Free enzyme (E)
Substrates (S)
Peptide bond
H2O
+
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Nucleic Acids
Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus
Their structural unit, the nucleotide, is composed of N-containing base, a pentose sugar, and a phosphate group
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Nucleic Acids
Five nitrogen bases contribute to nucleotide structure – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U)
Two major classes – DNA and RNA
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Deoxyribonucleic Acid (DNA)
Double-stranded helical molecule found in the nucleus of the cell
Replicates itself before the cell divides, ensuring genetic continuity
Provides instructions for protein synthesis
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Structure of DNA
Figure 2.22a
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Structure of DNA
Figure 2.22b
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Ribonucleic Acid (RNA)
Single-stranded molecule found in both the nucleus and the cytoplasm of a cell
Uses the nitrogenous base uracil instead of thymine
Three varieties of RNA: messenger RNA, transfer RNA, and ribosomal RNA
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Adenosine Triphosphate (ATP)
Source of immediately usable energy for the cell
Adenine-containing RNA nucleotide with three phosphate groups
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Adenosine Triphosphate (ATP)
Figure 2.23
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Solute Solute transported
Contracted smoothmuscle cell
Product made
Relaxed smoothmuscle cell
Reactants
Membraneprotein
P Pi
ATP
PX X
Y
Y
+
(a) Transport work
(b) Mechanical work
(c) Chemical work
Pi
Pi
+ADP
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Solute
Membraneprotein
P
ATP
(a) Transport work
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Solute Solute transported
Membraneprotein
P Pi
ATP
(a) Transport work
Pi
+ADP
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Relaxed smoothmuscle cell
ATP
(b) Mechanical work
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Contracted smoothmuscle cell
Relaxed smoothmuscle cell
ATP
(b) Mechanical work
Pi
+ADP
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Reactants
ATP
PX
Y+
(c) Chemical work
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Product madeReactants
ATP
PX X
Y
Y
+
(c) Chemical work
Pi
Pi
+ADP
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24
Solute Solute transported
Contracted smoothmuscle cell
Product made
Relaxed smoothmuscle cell
Reactants
Membraneprotein
P Pi
ATP
PX X
Y
Y
+
(a) Transport work
(b) Mechanical work
(c) Chemical work
Pi
Pi
+ADP