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BIOL 2401
Biol 2401
Fundamentals of Anatomy and Physiology
www.biol2401.weebly.com
[email protected]
(210) 486-2370
© 2012 Pearson Education, Inc.
2
The Chemical Level of
Organization
PowerPoint® Lecture Presentations prepared by
Jason LaPres
Lone Star College—North Harris
© 2012 Pearson Education, Inc.
An Introduction to the Chemical Level of Organization
Learning Outcomes
2-1 Describe an atom and how atomic structure affects interactions between atoms.
2-2 Compare the ways in which atoms combine to form molecules and compounds.
2-3 Distinguish among the major types of chemical reactions that are important for
studying physiology.
2-4 Describe the crucial role of enzymes in metabolism.
2-5 Distinguish between organic and inorganic compounds.
2-6 Explain how the chemical properties of water make life possible.
2-7 Discuss the importance of pH and the role of buffers in body fluids.
2-8 Describe the physiological roles of inorganic compounds.
2-9 Discuss the structures and functions of carbohydrates.
2-10 Discuss the structures and functions of lipids.
2-11 Discuss the structures and functions of proteins.
2-12 Discuss the structures and functions of nucleic acids.
2-13 Discuss the structures and functions of high- energy compounds.
2-14 Explain the relationship between chemicals and cells.
© 2012 Pearson Education, Inc.
An Introduction to the Chemical Level of Organization
Chemistry
Is the science of change. It is the science that deals with the structure of
matter (anything that takes up space and has mass, the amount of
material in matter). (Mass is not weight).
Topics of this chapter include:
The structure of atoms
The basic chemical building blocks
How atoms combine to form increasingly complex structures
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2-1 Atoms and Atomic Structure
Matter is made up of atoms
Atoms join together to form chemicals with different characteristics
Chemical characteristics determine physiology at the molecular and
cellular levels
Subatomic Particles of the Atom
Proton
Positive charge, 1 mass unit
Neutron
Neutral, 1 mass unit
Electron
Negative charge, low mass
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An Atom
Nucleus
(Hydrogen
does not have a neutron)
Electron Cloud
Hydrogen Atom
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Atoms and Atomic Structure
An element is a pure substance composed of atoms of only one
kind because atoms are the smallest particles of an element that
still retain the characteristics of that element.
Only 92 elements exist in nature.
All of these elements can be found on the Periodic Table of
Elements.
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Atoms and Atomic Structure
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Atoms and Atomic Structure
.Sample of one element on Periodic Table of Elements
1
H
Hydrogen
1.00974
Atomic Number
Symbol
Name of Element
Atomic Mass
1 Practice finding information using the Periodic Table of Elements.
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Table 2-1 Principal Elements in the Human Body
Human body consists many elements. These are the most abundant.
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Table 2-1 Principal Elements in the Human Body
Fourteen additional elements present in very small
amounts.
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2-1 Atoms and Atomic Structure
Elements and Isotopes
Elements are determined by the atomic number of an atom
Remember atomic number = number of protons
Isotopes are the specific version of an element based on its mass
number
Mass number = number of protons plus the number of neutrons
Only neutrons are different because the number of protons
determines the element
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Atoms and Atomic Structure
Radioisotopes are isotopes with unstable nuclei and spontaneously
break down and emit subatomic particles or radiation in measurable
amounts.
The break-down process is called radioactive decay. Strongly
radioactive isotopes are dangerous, causing destruction of cells
and damage to living tissues.
Weakly radioactive isotopes are used in diagnostic procedures.
Russian Spy Poisoned with Polonium
http://news.bbc.co.uk/2/hi/uk_news/6180682.stm
Yassar Araphat Poisoned with Polonium
http://content.usatoday.com/communities/ondeadline/post/2012/07/aljazeera-tests-hint-yasser-arafat-died-of-polonium-poisoning/1
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Figure 2-1 The Structure of Hydrogen Atoms
Electron shell
Hydrogen-1
mass number: 1
A typical hydrogen
nucleus contains a
proton and no neutrons.
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Hydrogen-2,
deuterium
Hydrogen-3,
tritium
mass number: 2
mass number: 3
A deuterium (2H)
nucleus contains a
proton and a neutron.
A tritium (3H) nucleus
contains a pair of
neutrons in addition
to the proton.
2-1 Atoms and Atomic Structure
Atomic Weights (expressed in atomic mass units—amu)
Exact mass of all particles
Measured in moles (mol)—a quantity with a weight in grams equal to
the element’s atomic weight. One mole of a given element always
contains the same number of atoms as one mole of any other element.
That number is called Avogadro’s number—6.023 x 1023 or about 600
billion trillion.
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2-1 Atoms and Atomic Structure
Electrons and Energy Levels
Electrons in the electron cloud determine the reactivity of an atom
The electron cloud contains shells, or energy levels that hold a
maximum number of electrons
Lower shells fill first
Outermost shell is the valence shell, and it determines
bonding
The number of electrons per shell corresponds to the number
of atoms in that row of the Periodic Table.
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Atoms and Atomic Structure
Energy Levels
Level
Maximum Number of Electrons
1
2
2
8
3
8
Practice the energy levels for the element that you had on the Periodic Table
of Elements.
Example: Element
H
Nucleus
Electron Energy
1p/0n
1
2 Write the electron configurations for C, O, Na, Cl, Ar
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Figure 2-2 The Arrangement of Electrons into Energy Levels
The first energy level
can hold a maximum of
two electrons.
Hydrogen, H
Atomic number: 1
Mass number: 1
1 electron
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Helium, He
Atomic number: 2
Mass number: 4
(2 protons  2 neutrons)
2 electrons
Figure 2-2 The Arrangement of Electrons into Energy Levels
The second and third
energy levels can
each contain up to 8
electrons.
Lithium, Li
Atomic number: 3
Mass number: 6
(3 protons  3 neutrons)
3 electrons
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Neon, Ne
Atomic number: 10
Mass number: 20
(10 protons  10 neutrons)
10 electrons
2-2 Molecules and Compounds
Chemical Bonds
Involve the sharing, gaining, and losing of electrons in the valence shell
Three major types of chemical bonds
Ionic bonds
Attraction between cations (electron donor) and anions (electron
acceptor)
Covalent bonds
Strong electron bonds involving shared electrons
Hydrogen bonds
Weak polar bonds based on partial electrical attractions
3 What is the principal difference between an ionic bond and a
covalent bond?
.
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2-2 Molecules and Compounds
Chemical Bonds
Form molecules and/or compounds
Molecules
Two or more atoms joined by strong bonds
Compounds
Two or more atoms OF DIFFERENT ELEMENTS joined by
strong or weak bonds
Compounds are all molecules, but not all molecules are
compounds
H2 = molecule only
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H2O = molecule and compound
2-2 Molecules and Compounds
Ionic Bonds
One atom—the electron donor—loses one or more electrons and
becomes a cation, with a positive charge
Another atom—the electron acceptor—gains those same
electrons and becomes an anion, with a negative charge
Attraction between the opposite charges then draws the two ions
together
4 What are cations and anions?
Cations are positively charged ions and anions are negatively charged ions.
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Figure 2-3a The Formation of Ionic Bonds
Formation of ions
Sodium atom
Attraction between
opposite charges
Formation of an
ionic compound
Sodium ion (Na)
Sodium chloride (NaCl)
Chlorine atom
Chloride ion (Cl)
1 A sodium (Na) atom loses an
electron, which is accepted by a chlorine (Cl) atom. 2 Because the
sodium (Na) and chloride (Cl) ions have opposite charges, they are
attracted to one another. 3 The association of sodium and chloride
ions forms the ionic compound sodium chloride.
Formation of an ionic bond.
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Figure 2-3b The Formation of Ionic Bonds
Chloride ions
(Cl)
Sodium ions
(Na)
Na+Cl-
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Sodium chloride
crystal. Large
numbers of sodium and
chloride ions form a
crystal of sodium
chloride (table salt).
2-2 Molecules and Compounds
Covalent Bonds
• Involve the sharing of pairs of electrons between atoms
• One electron is donated by each atom to make the pair of electrons
• Sharing one pair of electrons is a single covalent bond
• Sharing two pairs of electrons is a double covalent bond
• Sharing three pairs of electrons is a triple covalent bond
Single covalent bond
Double covalent bond
Double covalent bond
Double covalent bond/Free radical
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2-2 Molecules and Compounds
Covalent Bonds
Nonpolar covalent bonds
Involve equal sharing of electrons because atoms involved in the bond have
equal pull for the electrons
Polar covalent bonds
Involve the unequal sharing of electrons because one of the atoms involved in
the bond has a disproportionately strong pull on the electrons
Form polar molecules — like water
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2-2 Molecules and Compounds
Hydrogen Bonds
Bonds between adjacent molecules, not atoms
Involve slightly positive and slightly negative portions of polar molecules
being attracted to one another
Hydrogen bonds between H2O molecules cause surface tension
(phenomenon at the surface of the water when the attraction
between molecules slows the rate of evaporation).
Hydrogen
Oxygen
Hydrogen bond
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2-2 Molecules and Compounds
States of Matter
Solid
Constant volume and shape
Liquid
Constant volume but changes shape
Gas
Changes volume and shape
Water is the only substance that occurs as a solid (ice), a liquid (water), and a
gas (water vapor at temperatures compatible with life.
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2-2 Molecules and Compounds
Molecular Weights
The molecular weight of a molecule is the sum of the
atomic weights of its component atoms
H = approximately 1
O = approximately 16
H2 = approximately 2
H2O = approximately 18
What is the molecular weight of these compounds?
C6H12O6
H2SO4
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72+12+96 = 180g
2+32+64 = 98g
2-3 Chemical Reactions
In a Chemical Reaction
Either new bonds are formed or existing bonds are broken
Reactants
Materials going into a reaction
Products
Materials coming out of a reaction
Metabolism
All of the reactions that are occurring at one time
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5 Write the chemical notation for MOLECULES of water.
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Molecules and Compounds
First Law of Thermodynamics is an expression of the principle of
conservation of energy.
The law expresses that energy can be transformed, i.e. changed
from one form to another but cannot be created or destroyed.
How does this equation demonstrate the law?
2 H2 + O2 → 2 H2O
Balance the following equation.
___CO2 + ___H2O + Energy → C6H12O6 + ___ O2
6 CO2 + 6 H20 + Energy → C6H12O6 + 6 O2
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2
2
3
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3
1
3
7
6
4
1
1
3
2-3 Chemical Reactions
Basic Energy Concepts
Energy
The power to do work
Work
A change in mass or distance
Kinetic energy
Energy of motion
Potential energy
Stored energy
Chemical energy
Potential energy stored in chemical bonds
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2-3 Chemical Reactions
Types of Chemical Reactions
Decomposition reaction (catabolism)
Synthesis reaction (anabolism)
Exchange reaction
Reversible reaction
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2-3 Chemical Reactions
Decomposition Reaction (Catabolism)
Breaks chemical bonds
AB A + B
Hydrolysis A-B + H2O A-H + HO-B
Synthesis Reaction (Anabolism)
Forms chemical bonds
A + B AB
Dehydration synthesis (condensation reaction)
A-H + HO-B A-B + H2O
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2-3 Chemical Reactions
Exchange Reaction
Involves decomposition first, then synthesis
AB + CD AD + CB
Reversible Reaction
A + B AB
At equilibrium the amounts of chemicals do not change even
though the reactions are still occurring
Reversible reactions seek equilibrium, balancing opposing
reaction rates
Add or remove reactants
Reaction rates adjust to reach a new equilibrium
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2-4 Enzymes
Chemical Reactions
Cells cannot start without help
Activation energy is the amount of energy needed to get a reaction
started
Enzymes are protein catalysts that lower the activation energy of
reactions. It only affects the rate of the reaction, not the direction or
products.
Without enzyme
Reactants
With enzyme
Stable product
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2-4 Enzymes
Exergonic (Exothermic) Reactions
Produce more energy than they use
Endergonic (Endothermic) Reactions
Use more energy than they produce
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2-5 Organic and Inorganic Compounds
Major Classes or Chemical Compounds
Nutrients
Essential molecules obtained from food
Metabolites
Molecules made or broken down in the body
Inorganic Compounds
Molecules not based on carbon and hydrogen
Carbon dioxide, oxygen, water, and inorganic acids, bases, and salts
Organic Compounds
Molecules based on carbon and hydrogen
Carbohydrates, proteins, lipids, and nucleic acids
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2-6 Properties of Water
Water
Accounts for up to two-thirds of your total body weight
A solution is a uniform mixture of two or more
substances
It consists of a solvent, or medium, in which atoms,
ions, or molecules of another substance, called a
solute, are individually dispersed.
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2-6 Properties of Water
Unusual Properties of Water
Solubility
Water’s ability to dissolve a solute in a solvent to make a solution
Reactivity
Most body chemistry occurs in water
High Heat Capacity
Water’s ability to absorb and retain heat
Lubrication
To moisten and reduce friction
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2-6 Properties of Water
The Properties of Aqueous Solutions
Ions and polar compounds undergo ionization, or
dissociation in water
Polar water molecules form hydration spheres around
ions and small polar molecules to keep them in
solution
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6 Describe the difference between sodium chloride in solution and glucose in solution.
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2-6 Properties of Water
The Properties of Aqueous Solutions
Electrolytes and body fluids
Electrolytes are inorganic ions that conduct electricity in
solution
Electrolyte imbalance seriously disturbs vital body
functions
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Table 2-2 Important Electrolytes that Dissociate in Body Fluids
An electrolyte is a soluble inorganic molecules whose ions will conduct an
electrical current
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2-6 Properties of Water
The Properties of Aqueous Solutions
Hydrophilic and hydrophobic compounds
Hydrophilic
hydro- = water, philos = loving
Interacts with water
Includes ions and polar molecules
Hydrophobic
phobos = fear
What is hydrophobia?
RABIES – an acute deadly virus disease of the nervous system
transmitted by the bite of an affected animal.
Does NOT interact with water
Includes nonpolar molecules, fats, and oils
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2-6 Properties of Water
Colloids and Suspensions
Colloid
A solution of very large organic molecules
For example, blood plasma
Suspension
A solution in which particles settle (sediment)
For example, whole blood
Concentration
The amount of solute in a solvent (mol/L, mg/mL)
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2-7 pH and Homeostasis
Hydrogen ions are extremely reactive in solution, they will break
chemical bonds, change the shapes of complex molecules, and
disrupt cell and tissue functions. The concentration of hydrogen
ions in body fluids must be regulated precisely.
pH
The concentration of hydrogen ions (H+) in a solution
Neutral pH
A balance of H+ and OH
Pure water = 7.0 (1 x 10 -7 mol/L. -(-7) or 7.
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2-7 pH and Homeostasis
Acidic pH Lower Than 7.0
High H+ concentration
Low OH concentration
Basic (or alkaline) pH Higher Than 7.0
Low H+ concentration
High OH concentration
pH of Human Blood
Ranges from 7.35 to 7.45
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Figure 2-10 pH and Hydrogen Ion Concentration
pH Scale
Has an inverse relationship with H+ concentration
More H+ ions mean lower pH, less H+ ions mean higher pH
1 mol/L
hydrochloric
acid
Beer,
vinegar,
wine, Tomatoes,
pickles grapes
Stomach
acid
Extremely
acidic
pH 0
[H] 100
(mol/L)
1
101
Urine
Saliva,
milk
Increasing concentration of H
2
102
3
103
4
104
5
105
1 mol/L
sodium
hydroxide
Blood Ocean Household
Pure Eggswater
bleach
water
Neutral
6
106
7
107
Household
ammonia
Increasing concentration of OH
8
108
9
109
10
1010
11
1011
12
1012
Oven
cleaner
Extremely
basic
13
1013
14
1014
7 Which pH is more acidic: 6.82 or 9.17? Which pH is closer to neutral:
8.41 or 5.59?
pH 6.82 is more acidic.
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Both 8.41 and 5.59 are 1.41 units from 7.
2-8 Inorganic Compounds
Acid
A solute that adds hydrogen ions to a solution—proton donor
Strong acids dissociate completely in solution
Base
A solute that removes hydrogen ions from a solution—proton acceptor
Strong bases dissociate completely in solution
Weak Acids and Weak Bases
Fail to dissociate completely
Help to balance the pH
Salts
Solutes that dissociate into cations and anions other than hydrogen ions and
hydroxide ions
Example: Table salt NaCl → Na+ and Cl-
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2-8 Inorganic Compounds
Buffers and pH Control
Buffers
Weak acid/salt compounds
Neutralize either strong acid or strong base
Sodium bicarbonate (NaHCO3) is very important in
humans
Antacids
Basic compounds that neutralize acid and form a salt
Alka-Seltzer, Tums, Rolaids, etc.
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BIOL 2401-094
• Fundamentals of Anatomy and Physiology
• Chapter 2
• [email protected]
• (210) 486-2370
© 2012 Pearson Education, Inc.
2-9 Carbohydrates
Organic Molecules
Contain H, C, and usually O
Are covalently bonded
Contain functional groups that determine chemistry
Carbohydrates
Lipids
Proteins (or amino acids)
Nucleic acids
Grouping of atoms occurring repeatedly that influence the properties of any molecule they are in.
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2-9 Carbohydrates
Carbohydrates
Contain carbon, hydrogen, and oxygen in a 1:2:1 ratio
Monosaccharide — simple sugar
Disaccharide — two sugars
Polysaccharide — many sugars
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2-9 Carbohydrates
Monosaccharides
Simple sugars with 3 to 7 carbon atoms
Glucose, fructose, galactose
Disaccharides
Two simple sugars condensed by dehydration synthesis
Sucrose, maltose
Polysaccharides
Many monosaccharides condensed by dehydration
synthesis
Glycogen, starch, cellulose
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Carbohydrates
Isomers are molecules with the same types of and numbers of atoms—but different structure.
8 How many hydroxyl groups does a molecule of glucose have? How many carbon
atoms are part of glucose’s carbon skeleton?
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Figure 2-12a The Formation and Breakdown of Complex Sugars
Two monosaccharides joined together form a disaccharide. Add additional monosaccharides or
dissacharides, and you get polysaccharides.
They are formed in a process called dehydration synthesis (condensation). Water is released.
DEHYDRATION
SYNTHESIS
Glucose
Fructose
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Sucrose
Figure 2-12b The Formation and Breakdown of Complex Sugars
Hydrolysis reverses the steps of dehydration synthesis. A complex molecule is
broken down by the addition of water.
HYDROLYSIS
Sucrose
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Glucose
Fructose
Figure 2-13 The Structure of the Polysaccharide Glycogen (animal starch)
Glucose
molecules
9 Which body cells store glycogen?
Muscle Cells
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Table 2-4 Carbohydrates in the Body
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2-10 Lipids
Lipids
Mainly hydrophobic molecules such as fats, oils, and
waxes
Made mostly of carbon and hydrogen atoms
Include:
Fatty acids
Eicosanoids
Glycerides
Steroids
Phospholipids and glycolipids
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2-10 Lipids
Fatty Acids
Long chains of carbon and hydrogen with a carboxyl
group (COOH) at one end
Are relatively nonpolar, except the carboxyl group
Fatty acids may be:
Saturated with hydrogen (no covalent bonds)
Unsaturated (one or more double bonds)
Monounsaturated = one double bond
Polyunsaturated = two or more double bonds
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Figure 2-14a Fatty Acids
Lauric acid (C12H24O2)
Lauric acid demonstrates two structural
characteristics common to all fatty acids: a
long chain of carbon atoms and a carboxyl
group (—COOH) at one end.
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Figure 2-14b Fatty Acids
Saturated
Unsaturated
Double Bond
A fatty acid is either saturated (has single
covalent bonds only) or unsaturated (has
one or more double covalent bonds). The
presence of a double bond causes a
sharp bend in the molecule.
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BIOL 2401
Something to Consider:
A diet containing large amounts of saturated fatty
acids has been shown to increase the risk of heart
disease and other cardiovascular problems.
The healthiest choices of unsaturated oils to use are
canola oils and olive oil.
Be careful of trans fatty acids (compounds from
polyunsaturated oils such are margarine) seem to
increase the risk of heart disease.
Foods high in omega-3 fatty acids (fish flesh and fish
oils) seem to reduce the risk of heart disease and
other inflammatory diseases. (rheumatoid arthritis).
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2-10 Lipids
Eicosanoids (Derived from the fatty acid called arachidonic acid)
Leukotrienes –Active in the immune system
Prostaglandins –Local hormones, short-chain fatty acids that produce
sensation of pain and in the uterus, help trigger labor contractions.
Prostaglandins are called local hormones
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2-10 Lipids
Glycerides are fatty acids attached to a glycerol molecule
Monoglyceride (glycerol + one fatty acid)
Diglyceride (glycerol + two fatty acids)
Triglycerides are the three fatty-acid tails
Also called triacylglycerols or neutral fats
Have three important functions
Energy source
Insulation
Protection
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Figure 2-16 Triglyceride Formation
Glycerol
Fatty acids
Fatty Acid 1
Saturated
Fatty Acid 2
Saturated
Fatty Acid 3
Unsaturated
DEHYDRATION
SYNTHESIS
HYDROLYSIS
Breakdown
Formation
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Triglyceride
2-10 Lipids
Steroids (large lipid molecules with a distinctive carbon framework)
Four rings of carbon and hydrogen with an assortment of
functional groups
Types of steroids:
Cholesterol
Component of plasma (cell) membranes
Estrogens and testosterone
Sex hormones
Corticosteroids and calcitriol
Metabolic regulation
Bile salts
Derived from steroids
10 What is the danger of a diet high in cholesterol?
The development of heart disease is the danger of high cholesterol
blood levels.
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Figure 2-17 Steroids
Cholesterol
Estrogen (females)
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Testosterone (males)
2-10 Lipids
Phospholipids and Glycolipids
Diglycerides attached to either a phosphate group
(phospholipid) or a sugar (glycolipid)
Generally, both have hydrophilic heads and
hydrophobic tails and are structural lipids,
components of plasma (cell) membranes
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11 Which portion of a phospholipid is hydrophilic, and which portion is hydrophobic?
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Table 2-5 Representative Lipids and Their Functions in the Body
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2-11 Proteins
Proteins
Are the most abundant and important organic molecules
Contain basic elements
Carbon (C), hydrogen (H), oxygen (O), and nitrogen
(N)
Basic building blocks
20 amino acids
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2-11 Proteins
Seven Major Protein Functions
Support
Structural proteins
Movement
Contractile proteins
Transport
Transport (carrier)
proteins
Buffering
Regulation of pH
Metabolic Regulation
Enzymes
Coordination and Control
Hormones
Defense
Antibodies
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2-11 Proteins
Protein Structure
Long chains of amino acids
Five components of amino acid structure
Central carbon atom
Hydrogen atom
Amino group (—NH2)
Carboxyl group (—COOH)
Variable side chain or R group
Hydrogen atom
Amino Acid
Central Carbon
Carboxyl Group
R group(variable side chain)
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2-11 Proteins
Hooking Amino Acids Together
Requires a dehydration synthesis between:
The amino group of one amino acid and the carboxyl group of
another amino acid
Forms a peptide bond resulting in a peptide
Two amino acids – dipeptide
Three amino acids – tripeptide
Chain of amino acids - polypeptide
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Figure 2-20 The Fomation of Peptide Bonds
Peptide Bond Formation
Glycine (gly)
DEHYDRATION
SYNTHESIS
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Alanine (ala)
HYDROLYSIS
Peptide bond
BIOL 2401
Essential Amino Acids: Arginine Isoleucine
Histidine Leucine Methionine Lysine
Phenylalanine Tryptophan Threonine Valine
These cannot be made by the body and must be
obtained in the foods we eat.
Non-Essential Amino Acids: Alanine
Asparagine Aspartic Acid Cysteine Glutamic Acid
Cysteine Glutamine Glycine
These are made by the body.
12 Differentiate between essential amino acids and non-essential amino acids.
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2-11 Proteins
Protein Shape
Primary structure
The sequence of amino acids along a polypeptide
Secondary structure
Hydrogen bonds form spirals or pleats
Tertiary structure
Secondary structure folds into a unique shape
Quaternary structure
Final protein shape — several tertiary structures together
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Figure 2-21 Protein Structure
A1
A3
A2
A5
A4
A7
A6
A8
A9
Primary
A2
A3
Linear chain of amino acids
A1
Hydrogen bond
Hydrogen
bond
A6
A2
A1
A3
A5
A4
A5
A9
A8
A7
A6
A11
A12
A13
A14
A10
A7
A9
Alpha-helix
OR
Secondary
Pleated sheet
OR
Heme units
Tertiary
Hemoglobin
(globular protein)
Keratin or collagen
(fibrous protein)
13 Do all proteins have a quaternary structure?
Quaternary
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2-11 Proteins
Classes of proteins are based on overall shape and properties.
Fibrous Proteins
Structural sheets or strands
Globular Proteins
Soluble spheres with active functions
Protein function is based on shape
Shape is based on sequence of amino acids
20 amino acids can be linked in many combinations creating many
proteins of varied shape and function.
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2-11 Proteins
Enzyme Function
Enzymes are catalysts
Proteins that lower the activation energy of a chemical reaction
Are not changed or used up in the reaction
Enzymes also exhibit:
Specificity — will only work on limited types of substrates
Saturation Limits — by their concentration
Regulation — by other cellular chemicals
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Figure 2-22 A Simplified View of Enzyme Structure and Function
Cofactors and Enzyme Function
Cofactor
An ion or molecule that binds to an enzyme before substrates can
bind -- Ca2+ Mg2+
Coenzyme
Non-protein organic cofactors (vitamins)
Isozymes
Two enzymes that can catalyze the same reaction
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2-11 Proteins
Effects of Temperature and pH on Enzyme Function
Denaturation
Loss of shape (tertiary or quaternary) and function
(becomes non-functional)
Due to
heat (temperatures above 1100)
pH (acidic or basic depending on enzyme)
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2-11 Proteins
Glycoproteins and Proteoglycans
Glycoproteins
Large protein + small carbohydrate
Includes enzymes, antibodies, hormones, and mucus
production
Proteoglycans
Large polysaccharides + polypeptides
Promote viscosity
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2-12 Nucleic Acids
Nucleic Acids
Are large organic molecules, found in the nucleus, which store and
process information at the molecular level
Deoxyribonucleic acid (DNA)
Determines inherited characteristics
Directs protein synthesis
Controls enzyme production
Controls metabolism
Ribonucleic acid (RNA)
Controls intermediate steps in protein synthesis
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2-12 Nucleic Acids
Structure of Nucleic Acids
DNA and RNA are strings of nucleotides
Nucleotides are the building blocks of DNA and RNA
Have three molecular parts
A pentose sugar (deoxyribose or ribose)
Phosphate group
Nitrogenous base (A, G, T, C, or U)
Sugar
Phosphate Group
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Nitrogenous Base
Purines
Adenine
Guanine
Pyrimidines
Cytosine
Thymine
DNA only
Uracil
RNA only
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2-12 Nucleic Acids
DNA and RNA
DNA is double stranded, and the bases form hydrogen bonds to hold the
DNA together
Sometimes RNA can bind to itself but is usually a single strand
DNA forms a twisting double helix
Complementary base pairs
Purines pair with pyrimidines
DNA
Adenine (A) and thymine (T)
Cytosine (C) and guanine (G)
RNA
Uracil (U) replaces thymine (T)
Types of RNA
Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)
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Figure 2-24 The Structure of Nucleic Acids
Phosphate
group
Deoxyribose
Adenine
Thymine
Hydrogen bond
DNA strand 1
DNA strand 2
RNA molecule.
14 Which bases always pair with each other?
A to T and G to C
Cytosine
DNA molecule.
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Guanine
Table 2-6 Comparison of RNA with DNA
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2-13 High-Energy Compounds
Nucleotides Can Be Used to Store Energy
Adenosine diphosphate (ADP)
Two phosphate groups; di- = 2
Adenosine triphosphate (ATP)
Three phosphate groups; tri- = 3
Phosphorylation
Adding a phosphate group to ADP with a high-energy
bond to form the high-energy compound ATP
Adenosine triphosphatase (ATPase)
The enzyme that catalyzes the conversion of ATP to
ADP
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Figure 2-25 The Structure of ATP
Adenine
Ribose
Phosphate
Phosphate
Phosphate
High-energy bonds
Adenosine
Adenosine monophosphate (AMP)
Adenosine diphosphate (ADP)
Adenosine triphosphate (ATP)
Adenine
Phosphate groups
Ribose
Adenosine
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2-14 Chemicals and Cells
Chemicals and Cells
Biochemical building blocks form functional units called cells
Metabolic turnover lets your body grow, change, and adapt to new conditions and
activities
Your body recycles and renews all of its chemical components at intervals ranging
from minutes to years
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Table 2-7 Classes of Inorganic and Organic Compounds
15 Name the dissolved gases and give their functions.
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