Transcript chapt02_chem

Chapter 2
Lecture Outline
2-1
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The Chemistry of Life
• Atoms, Ions and Molecules
• Water and Mixtures
• Energy and Chemical Reactions
• Organic Compounds
2-2
The Chemical Elements
• Element - simplest form of matter to have
unique chemical properties
• Atomic number of an element - number of
protons in its nucleus
– periodic table
• elements arranged by atomic number
– 24 elements have biological role
• 6 elements = 98.5% of body weight
– oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus
• trace elements in minute amounts
2-3
2-4
Atomic Structure
• Nucleus - center of atom
– protons: single + charge, mass = 1 amu (atomic
mass unit)
– neutrons: no charge, mass = 1 amu
– Atomic Mass of an element is approximately
equal to its total number of protons and neutrons
2-5
Atomic Structure
• Electrons – in concentric clouds that surround the
nucleus
– electrons: single negative charge, very low mass
• determine the chemical properties of an atom
• the atom is electrically neutral because number of
electrons is equal to the number of protons
– valence electrons in the outermost shell
• determine chemical bonding properties of an atom
2-6
Planetary Models of Elements
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Second
energy
level
First
energy
level
Carbon (C) 6p+, 6e-, 6n0
Atomic number = 6
Atomic mass
= 12
Third
energy
level
Nitrogen (N) 7p+, 7e-, 7n0
Atomic number = 7
Atomic mass
= 14
Sodium (Na) 11p+, 11e-, 12n0
Atomic number = 11
Atomic mass
= 23
Fourth
energy
level
Potassium (K) 19p+, 19e-, 20n0
Atomic number = 19
Atomic mass
= 39
p+ represents protons, no represents neutrons
2-7
Ions and Ionization
• Ions – charged particles with unequal number
of protons and electrons
• Ionization transfer of
electrons from one
atom to another
( stability of
valence shell)
11 protons
12 neutrons
11 electrons
Sodium
atom (Na)
17 protons
18 neutrons
17 electrons
Chlorine
atom (Cl)
1 Transfer of an electron from a sodium atom to a chlorine atom
Figure 2.4 (1)
2-8
Anions and Cations
• Anion
– atom that gained electrons (net negative charge)
• Cation
– atom that lost an electron (net positive charge)
• Ions with opposite charges are attracted to each
other
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–
+
Figure 2.4 (2)
11 protons
12 neutrons
10 electrons
Sodium
ion (Na+)
17 protons
18 neutrons
18 electrons
Chloride
ion (Cl–)
Sodium chloride
2 The charged sodium ion (Na+) and chloride ion (Cl–) that result
2-9
Electrolytes
• Salts that ionize in water and form solutions
capable of conducting an electric current.
• Electrolyte importance
– chemical reactivity
– osmotic effects (influence water movement)
– electrical effects on nerve and muscle tissue
• Electrolyte balance is one of the most important
considerations in patient care.
• Imbalances have ranging effects from muscle
cramps, brittle bones, to coma and cardiac arrest
2-10
2-11
Molecules and Chemical Bonds
• Molecules
– chemical particles composed of two or more
atoms united in a chemical bond
• Compounds
– molecules composed of two or more different
elements
• Molecular formula
– identifies constituent elements and shows how
many of each are present (e.g. H2O)
2-12
Chemical Bonds
TABLE 2.3
Types of Chemical Bonds
• Chemical bonds –
forces that hold
molecules together, or
attract one molecule to
another
• Types of Chemical
Bonds
– Ionic bonds
– Covalent bonds
– Hydrogen bonds
– Van der Waals force
2-13
Ionic Bonds
• The attraction of a cation to an anion
• electron donated by one and received by the
other
• Relatively weak attraction that is easily
disrupted in water, as when salt dissolves
2-14
Covalent Bonds
• Formed by sharing electrons
• Types of covalent bonds
– single - sharing of single pair electrons
– double - sharing of 2 pairs of electrons
– nonpolar covalent bond
• shared electrons spend approximately equal time
around each nucleus
• strongest of all bonds
– polar covalent bond
• if shared electrons spend more time orbiting one nucleus
than they do the other, they lend their negative charge to
2-15
the area they spend most time
Single Covalent Bond
• One pair of electrons are shared
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p+
+
p+
Hydrogen atom Hydrogen atom
p+
p+
H
H
Hydrogen molecule (H2)
(a)
Figure 2.6a
2-16
Double covalent bonds:
Two pairs of electrons are shared each C=O bond
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Oxygen atom
Carbon atom
Oxygen atom
8p+
8n0
6p+
6n0
8p+
8n0
O
C
O
Carbon dioxide molecule (CO2)
(b)
Figure 2.6b
2-17
Nonpolar /Polar Covalent
Bonds
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C
Nonpolar covalent
C
C bond
C
(a)
O
–
(b)
Polar covalent
O
H bond
H
+
Electrons
shared
equally
Electrons
shared
unequally
Figure 2.7
2-18
Hydrogen Bonds
• Hydrogen bond – a weak attraction between a
slightly positive hydrogen atom in one molecule
and a slightly negative oxygen or nitrogen atom
in another.
• Water molecules are weakly attracted to each
other by hydrogen bonds
• very important to physiology
– protein structure
– DNA structure
2-19
Hydrogen Bonding in Water
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H
O
H
H
H
O
O
H
H
O
H
Covalent bond
H
Figure 2.8
Hydrogen bond
O
Water molecule
H
H
2-20
Van der Waals Forces
• Fluctuations in electron density in electron cloud of a
molecule creates polarity for a moment, attracts adjacent
molecules for a moment
• Only 1% as strong as a covalent bond
• when two surfaces or large molecules meet, the attraction
between large numbers of atoms can create a very strong
attraction
– important in protein folding
– important with protein binding with hormones
– association of lipid molecules with each other
2-21
Water
• Water’s polar covalent bonds and its
V-shaped molecule gives water a set of
properties that account for its ability to
support life.
– solvency
– cohesion
– adhesion
– chemical reactivity
– thermal stability
2-22
Solvency
• Solvency - ability to dissolve other chemicals
• water is called the Universal Solvent
– Hydrophilic – substances that dissolve in water
• molecules must be polarized or charged
– Hydrophobic - substances that do not dissolve in
water
• molecules are non-polar or neutral (fat)
• Virtually all metabolic reactions depend on the
solvency of water
2-23
Water as a Solvent
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–
+
(a)
Na+
(b)
Oxygen
+
105°
Hydrogen
Cl –
Figure 2.9
• Polar water molecules overpower the ionic
bond in Na+ Cl– form hydration spheres around each ion
– water molecules: negative pole faces Na+, positive
pole faces Cl2-24
Chemical Reactivity of Water
• is the ability to participate in chemical
reactions
– water ionizes into H+ and OH– water ionizes other chemicals (acids and
salts)
– water involved in hydrolysis and
dehydration synthesis reactions
2-25
Thermal Stability of Water
• Water helps stabilize the internal temperature of
the body
– has high heat capacity – the amount of heat required to
raise the temperature of 1 g of a substance by 1 degree C.
• hydrogen bonds inhibit temperature increases by
inhibiting molecular motion
• water absorbs heat without changing temperature very
much
– effective coolant
• 1 ml of perspiration removes 500 calories (of heat)
2-26
Solution, Colloid and Suspension
Solution Colloid
Figure 2.10 (2)
Suspension
2-27
• Solution – consists of
particles of matter called the
solute mixed with a more
abundant substance (usually
water) called the solvent
Solutions
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• Solute can be gas, solid or
liquid
• Solutions are defined by the
following properties:
– solute particles under 1nm
– do not scatter light
– pass through most
membranes
– will not separate on
standing
(a)
(b)
(c)
(d)
© Ken Saladin
Figure 2.10 (1)
2-28
• Most colloids in the body are
mixtures of protein and water
• Many can change from liquid
to gel state
Colloids
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• Defined by the following
physical properties:
– particles range from 1 –
100 nm in size
– scatter light and are
usually cloudy
– particles too large to pass
through semipermeable
membrane
– particles remain mixed
with the solvent when
mixture stands
(a)
(b)
(c)
(d)
© Ken Saladin
Figure 2.10 (1)
2-29
Suspensions and Emulsions
• Suspension
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– defined by the following
physical properties
• particles exceed 100nm
• too large to penetrate
selectively permeable
membranes
• cloudy or opaque in
appearance
• separates on standing
• Emulsion
– suspension of one liquid in
another
• fat in breast milk
(a)
(b)
(c)
(d)
© Ken Saladin
Figure 2.10 (1)
2-30
2-31
***Acids, Bases and pH
• An acid is proton donor (releases H+ ions in
water)
• A base is proton acceptor (accepts H+ ions)
– releases OH- ions in water
• pH – a measure derived from the molarity of H+
– a pH of 7.0 is neutral pH
(H+ = OH-)
– a pH of less than 7 is acidic solution (H+ > OH-)
– a pH of greater than 7 is basic solution (OH- > H+ )
2-32
pH
• pH - measurement of molarity of H+ [H+] on a logarithmic
scale
– pH = -log [H+] thus pH = -log [10-3] = 3
• a change of one number on the pH scale represents a 10
fold change in H+ concentration
– a solution with pH of 4.0 is 10 times as acidic as one with pH of 5.0
• Our body uses buffers to resist changes in pH
– slight pH disturbances can disrupt physiological functions and alter
drug actions
– pH of blood ranges from 7.35 to 7.45
– deviations from this range cause tremors, paralysis or even death
2-33
Gastric juice
(0.9–3.0) Lemon
juice
1M
Hydrochloric (2.3)
Acid (0)
pH Scale
Pure water
Household
Bread,
Milk,
(7.0) Egg white bleach
saliva
Wine, Bananas, black
(9.5)
(8.0)
vinegar tomatoes coffee (6.3 -–6.6)
(5.0)
(2.4 -–3.5)
(4.7)
3
2
4
5
6
7
8
9
10
Household
ammonia
(10.5 - 11.0)
Oven cleaner, lye
(13.4)
1 M sodium
hydroxide
(14)
11
12
Neutral
13
1
0
14
Figure 2.12
2-34
Chemical Reaction
• chemical reaction – a process in which a
covalent or ionic bond is formed or broken
• chemical equation –symbolizes the
course of a chemical reaction
– reactants (on left)  products (on right)
• classes of chemical reactions
– decomposition reactions
– synthesis reactions
– exchange reactions
2-35
Decomposition
Reactions
• Large molecule breaks
down into two or more
smaller ones
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Starch molecule
• AB  A + B
Figure 2.13a
Glucose molecules
(a) Decomposition reaction
2-36
Synthesis
Reactions
• Two or more small
molecules combine to
form a larger one
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Amino acids
• A + B  AB
Figure 2.13b
Protein molecule
2-37
(b) Synthesis reaction
Exchange Reactions
• Two molecules exchange atoms or group of
atoms
• AB+CD 
ABCD

AC + BD
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Stomach acid (HCl)
and sodium
bicarbonate
(NaHCO3) from the
pancreas combine
to form NaCl and
H2CO3.
AB + CD
AC
C
A
D
B
C
A
D
B
C
A
D
B
+
Figure 2.13c
BD
(c) Exchange reaction
2-38
Reversible Reactions
• Can go in either direction under different
circumstances
• symbolized with double-headed arrow
• CO2 + H2O
H2CO3
HCO3- + H+
– most common equation discussed in this book
– respiratory, urinary, and digestive physiology
• Law of mass action determines direction
– proceeds from the side of equation with greater quantity
of reactants to the side with the lesser quantity
• Equilibrium exists in reversible reactions when the ratio of
products to reactants is stable
2-39
Reaction Rates
• Basis for chemical reactions is molecular motion and
collisions
– reactions occur when molecules collide with enough force and
the correct orientation
• Reaction Rates affected by:
– concentration: more reactants=faster rate
– temperature: higher temp=faster rate
– catalysts
• speed up reactions without permanent change to itself
• holds reactant molecules in correct orientation
• catalyst not permanently consumed or changed by the
reaction
• Enzymes – most important biological catalysts
2-40
Organic Chemistry
• Study of compounds containing carbon
• 4 categories of carbon compounds
– carbohydrates
– lipids
– proteins
– nucleotides and nucleic acids
2-41
Monomers and Polymers
• Macromolecules - very large organic
molecules
• proteins, DNA
• Polymers – molecules made of a repetitive
series of identical or similar subunits
(monomers)
2-42
Polymerization
• joining monomers to form a polymer
• dehydration synthesis is how living cells form
polymers
– a hydroxyl (-OH) group is removed from one monomer,
and a hydrogen (H+) from another
• producing water as a by-product
• hydrolysis – opposite of dehydration synthesis
– a water molecule ionizes into –OH and H+
– the covalent bond linking one monomer to the other is
broken
– the –OH is added to one monomer
2-43
– the H+ is added to the other
Dehydration Synthesis
• Monomers covalently bond together to form a
polymer with the removal of a water molecule
– A hydroxyl group is removed from one monomer and a
hydrogen from the next
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Dimer
Monomer 1
Monomer 2
O
OH HO
H+ + OH–
H2O
(a) Dehydration synthesis
Figure 2.15a
2-44
Hydrolysis
• Splitting a polymer (lysis) by the addition of a water
molecule (hydro)
– a covalent bond is broken
• All digestion reactions consist of hydrolysis reactions
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Dimer
Monomer 1
Monomer 2
OH
O
H2O
HO
H+ + OH–
(b) Hydrolysis
Figure 2.15b
2-45
Organic Molecules:
Carbohydrates
• hydrophilic organic molecules
• general formula
– (CH2O)n
n = number of carbon atoms
– for glucose, n = 6, so formula is C6H12O6
• names of carbohydrates often built from:
– word root ‘sacchar-’
– the suffix ’-ose’
– both mean ‘sugar’ or ‘sweet’
• monosaccharide or glucose
2-46
Monosaccharides
• Simplest carbohydrates
Glucose
CH2OH
O
H
– simple sugars
HO
• 3 important monosaccharides
– glucose, galactose and fructose
– same molecular formula - C6H12O6
Galactose
• glucose is blood sugar
OH
H
H
OH
OH
CH2OH
O
HO
• isomers
– produced by digestion of complex
carbohydrates
H
H
H
H
H
OH
H
H
OH
OH
Fructose
O
HOCH2
H
OH
H
HO
OH
H
Figure 2.16
CH2OH
2-47
Disaccharides
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• Sugar molecule
composed of 2
monosaccharides
Sucrose
CH2OH
O
H
H
OH
• 3 important
disaccharides
– sucrose - table sugar
• glucose + galactose
– maltose - grain products
• glucose + glucose
H
O
H
HO
CH2OH
OH
OH
H
Lactose
CH2OH
H
OH
O
HO
H
OH
OH
H
H
H
H
OH
O
H
• glucose + fructose
– lactose - sugar in milk
H
HO
H
CH2OH O
H
H
OH
H
O
H
CH2OH
Maltose
CH2OH
CH2OH
O
H
H
OH
H
H
O
HO
H
OH
O
H
H
OH
OH
H
H
H
Figure 2.17
OH
2-48
Polysaccharides
• long chains of glucose
• 3 polysaccharides of interest in humans
– Glycogen: energy storage polysaccharide in
animals
• made by cells of liver, muscles, brain, uterus, and vagina
• liver makes glycogen after a meal when glucose level is high,
then breaks it down later to maintain blood glucose levels
– Starch: energy storage polysaccharide in plants
• only significant digestible polysaccharide in the human diet
– Cellulose: structural molecule of plant cell walls
• fiber in our diet
2-49
Glycogen
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CH2OH
O
O
O
O
CH2OH
O
CH2OH
O
CH2
O
(a)
CH2OH
O
O
CH2OH
O
O
O
O
O
(b)
Figure 2.18
2-50
2-51
Organic Molecules: Lipids
• hydrophobic organic molecule
– composed of carbon, hydrogen and oxygen
– with high ratio of hydrogen to oxygen
• Less oxidized than carbohydrates, and thus has
more calories/gram
• Five primary types in humans
–
–
–
–
–
fatty acids
triglycerides
phospholipids
eicosanoids
steroids
2-52
Fatty Acids
• Chain of 4 to 24 carbon atoms
– carboxyl (acid) group on one end, methyl group on the other and
hydrogen bonded along the sides
• Types
–
–
–
–
saturated - carbon atoms saturated with hydrogen
unsaturated - contains C=C bonds without hydrogen
polyunsaturated – contains many C=C bonds
essential fatty acids – obtained from diet, body can not synthesize
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H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
O
C
H
HO
Palmitic acid (saturated)
CH3(CH2)14COOH
Figure 2.19
2-53
Triglycerides (Neutral Fats)
• 3 fatty acids covalently bonded to glycerol molecule
• triglycerides at room temperature
– when liquid called oils
• often polyunsaturated fats from plants
– when solid called fat
• saturated fats from animals
• Primary Function - energy storage, insulation and shock
absorption (adipose tissue)
2-54
Phospholipids
• similar to neutral fat
except that one fatty
acid replaced by a
phosphate group
CH3
N+
CH3
CH2
CH2
O
–O
• structural foundation
of cell membrane
P
O
Phosphate
group
Hydrophilic
region (head)
O
O
• Amphiphilic
– fatty acid “tails” are
hydrophobic
– phosphate “head” is
hydrophilic
Nitrogencontaining
group
(choline)
CH3
CH2
CH
O
O
C
C
O
(CH2)5 (CH2)12
CH
CH3
Glycerol
CH2
Fatty acid
tails
Hydrophobic
region (tails)
CH
(CH2)5
CH3
(a)
(b)
Figure 2.20a,b
2-55
Eicosanoids
• 20 carbon compounds derived from a fatty acid
called arachidonic acid
• hormone-like chemical signals between cells
• includes prostaglandins – produced in all
tissues
– role in inflammation, blood clotting, hormone action,
labor contractions, blood vessel diameter
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O
COOH
Figure 2.21
2-56
OH
OH
Steroids and Cholesterol
• Steroid – a lipid with 17 of its carbon atoms in four
rings
• Cholesterol - the ‘parent’ steroid from which the
other steroids are synthesized
– cortisol, progesterone, estrogens, testosterone and bile
acids
– synthesized only by animals
• 15% from diet, 85% internally synthesized
– important component of cell membranes
– required for proper nervous system function
2-57
Cholesterol
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H 3C
CH3
CH3
CH3
CH3
HO
Figure 2.22
2-58
2-59
Organic Molecules: Proteins
• Greek word meaning “of first importance”
– most
versatile molecules in the body
• protein - a polymer of amino acids
• amino acid – central carbon with 3 attachments
– amino group (NH2), carboxyl group (COOH) and radical
group (R group)
– properties of amino acid determined by -R group
2-60
Representative Amino Acids
Some nonpolar aa’s
Some polar aa’s
Methionine
H
Cysteine
H
H
N
N
C
H
CH2
CH2
S
C
H
CH3
O
OH
O
Tyrosine
H
SH
H
H
C
OH
Arginine
N
H
N
CH2
OH
H
C
O
CH2
C
C
H
H
C
NH2+
(CH2)3
O
C
NH2
C
OH
NH
Figure 2.23a
OH
(a)
• Note: they differ only in the R group
2-61
Naming of Peptides
• peptide – any molecule composed of two or more
amino acids joined by peptide bonds
• peptide bond – joins the amino group of one amino
acid to the carboxyl group of the next
– formed by dehydration synthesis
• Peptides named for the number of amino acids
–
–
–
–
–
dipeptides have 2
tripeptides have 3
oligopeptides have fewer than 10 to 15
polypeptides have more than 15
proteins have more than 50
2-62
Protein Structure and Shape
• Primary structure
– sequence of amino acids (encoded in the genes)
• Secondary structure
– coiled or folded shape held together by hydrogen
bonds
– hydrogen bonds between slightly negative C=O
and slightly positive N-H groups
– most common secondary structures are:
• alpha helix – springlike shape
• beta sheet – pleated, ribbonlike shape
2-63
Protein Structure and Shape
• Tertiary structure
– further bending and folding of proteins into globular and
fibrous shapes
• globular proteins –compact structure good for proteins
embedded in cell membrane or that move about in fluid
• fibrous proteins – slender filaments better suited for
roles as in muscle contraction and strengthening skin
• Quaternary structure
– associations of two or more separate polypeptide chains
2-64
Structure of Proteins
example: hemoglobin
Amino acids
Primary structure
Tertiary structure
Sequence of amino
acids joined by
peptide bonds
Folding and coiling
due to interactions
among R groups and
between R groups
and surrounding water
C
C
C
Secondary structure
C
C
C
C
Alpha helix or beta
sheet formed by
hydrogen bonding
Beta
chain
Heme
groups
Alpha
chain
Alpha
helix
Beta
sheet
Quaternary structure
Association of two
or more polypeptide
chains with each
other
Figure 2.24
2-65
Protein Conformation and
Denaturation
• Conformation – unique three dimensional shape of
protein crucial to function
– some proteins can reversibly change their conformation
• enzyme function
• muscle contraction
• opening and closing of cell membrane pores
• Denaturation
– extreme conformational change that destroys function
• extreme heat or pH
2-66
Protein Functions
• Structure
– keratin – tough structural protein
• gives strength to hair, nails, and skin surface
– collagen – durable protein contained in deeper layers of skin, bones,
cartilage, and teeth
• Communication
– some hormones and other cell-to-cell signals
– receptors to which signal molecules bind
• Membrane Transport
– channels in cell membranes that govern what passes through
– carrier proteins – transport solute particles to other side of membrane
– turn nerve and muscle activity on and off
2-67
Protein Functions
• Catalysis
– enzymes
• Recognition and Protection
– immune recognition
– antibodies
– clotting proteins
• Movement
– motor proteins - molecules with the ability to change shape
repeatedly (like in muscles)
• Cell adhesion
– proteins bind cells together
– immune cells bind to cancer cells
– keeps tissues from falling apart
2-68
Enzymes
• Enzymes - proteins that function as biological
catalysts
– permit reactions to occur rapidly at normal body
temperature
• Substrate - substance an enzyme acts upon
• Naming Convention
– named for substrate with -ase as the suffix
• amylase enzyme digests starch (amylose)
• Lowers activation energy - energy needed to get
reaction started
– enzymes facilitate molecular interaction
2-69
Enzyme Structure and Action
1. Substrate approaches active site on enzyme molecule
2. Substrate binds to active site forming enzyme-substrate
complex
- highly specific fit –’lock and key’
3. Enzyme breaks covalent bonds between monomers in
substrate
- adding H+ and OH- from water – Hydrolysis
4. Reaction products released
5. Enzyme remains unchanged and is ready to repeat the
process
2-70
Enzymatic Reaction Steps
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Enzyme and
substrate
Sucrose (substrate)
O
Active site
Sucrase (enzyme)
2
Enzyme–substrate
complex
O
Glucose
3
Enzyme
and reaction
products
Fructose
Figure 2.27
2-71
Enzymatic Action
• Re-usability of enzymes
– enzymes are not consumed by the reactions
• Astonishing speed
– one enzyme molecule can consume millions of substrate
molecules per minute
• Factors that change enzyme shape
– pH and temperature
– alters or destroys the ability of the enzyme to bind to
substrate
– enzymes vary in optimum pH
• salivary amylase works best at pH 7.0
• pepsin works best at pH 2.0
– temperature optimum for human enzymes – body
temperature (37 degrees C)
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Organic Molecules:
Nucleotides
• ATP – best known nucleotide
– adenine (nitrogenous base)
– ribose (sugar)
– phosphate groups (3)
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ATP (Adenosine Triphosphate)
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Adenine
NH2
Adenine
NH2
C
C
N
N
C
N
N
C
CH
HC
CH
C
HC
N
N
C
N
N
Adenosine
Ribose
Ribose
Triphosphate
–O
O
O
O
P O
P O
P
–O
–O
Monophosphate
O
CH2
O
O
–O
HO
H H
OH
P
CH2
O
H H
OH
(a) Adenosine triphosphate (ATP)
O
H H
O
H H
OH
(b) Cyclic adenosine monophosphate (cAMP)
Figure 2.29a, b
ATP contains adenine, ribose and 3 phosphate groups
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Adenosine Triphosphate (ATP)
• body’s most important energy-transfer molecule
• briefly stores energy gained from exergonic reactions
– releases it within seconds for physiological work
• holds energy in covalent bonds
– 2nd and 3rd phosphate groups have high energy
bonds
– most energy transfers to and from ATP involve
adding or removing the 3rd phosphate
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Sources and Uses of ATP
Glucose + 6 O2
are converted to
6 CO2 + 6 H2O
which releases
energy
which is used for
ADP + Pi
ATP
which is then available for
Muscle contraction
Ciliary beating
Active transport
Synthesis reactions
etc.
Figure 2.30
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