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SPE 3510Basic Anatomy and Physiology
Roxana Dev Omar Dev
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Chapter 2
The Chemical Basis of LifeThe Chemical Basis of Life
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Basic Chemistry
Matter, Mass, and WeightMatter: anything that occupies space and has mass
Mass: the amount of matter in an object
Weight: the gravitational force acting on an objectof a given mass
Elements and Atoms
Element: the simplest type of matter with unique
chemical properties; composed of atoms of only one
kind
Atom: smallest particle of an element that has
chemical characteristics of that element
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Atomic Structure
Atoms: composed ofsubatomic particles
Neutrons: no electrical
charge
Protons: one positive charge
Electrons: one negative
charge
Nucleus: formed by protons
and neutrons
Most of the volume of an
atom occupied by electrons
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Atomic Number and Mass
Number
Atomic Number: equal
to number of protons in
each atom which is equalto the number of
electrons
Mass Number: number
of protons plus numberof neutrons
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Isotopes and Atomic Mass
Isotopes: two or more forms of same element with samenumber of protons and electrons but different neutronnumber
For example; there are three types of hydrogen Denoted by using symbol of element preceded by mass number as
1H, 2H, 3H
Atomic Mass: average mass of naturally occurringisotopes
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Radioactive Isotopes
Forms of atoms that emit radioactivity such
as gamma rays, which can then be
measured Used clinically and in research
Examples of uses
Tracking hormone uptake
Treating cancer
Sterilization of materials to be used in surgery
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Electrons and Chemical Bonding Intramolecular bonding occurs
when outermost electrons areeither shared with or transferred toanother atom
Ionic Bonding: atomsexchange electrons
Covalent Bonding: two ormore atoms share electronpairs
Ion: an atom loses or gainselectrons and becomes charged
Cation: positively charged ion
Anion: negatively charged ion
In an ionic bond, cations andanions are attracted to each other
and remain close to each other
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Covalent Bonding
Atoms share one or morepairs of electrons Single covalent: two
atoms share one pair ofelectrons
Double covalent: Twoatoms share 4 electrons
Nonpolar covalent:Electronsshared equallybecause nuclei attract theelectrons equally
Polarcovalent: Electronsnot shared equallybecause one nucleusattracts the electrons morethan the other does
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Molecules and Compounds
Molecules: two or more atoms chemicallycombine to form an independent unit
Example: a hydrogen molecule (H2)
Compounds: a substance composed of twoor more different types of atoms chemically
combined
Example: water (H2O)
Molecular Mass: determined by adding up
atomic masses of its atoms or ions
Example: NaCl (22.99 + 35.45)
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Intermolecular Forces
Forces between molecules
Result from weak electrostatic attractions
between oppositely charged parts or
molecules, or between ions and molecules
Weaker than forces producing chemical
bonding
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Intermolecular Forces: Hydrogen Bonds
Occur when the positivelycharged H of one molecule isattracted to the negativelycharged O, N or F of anothermolecule For example, in water the
positively charged hydrogenatoms of one water moleculebond with the negativelycharged oxygen atoms of other
water molecules Hydrogen bonds play animportant role in determiningthe shape of complexmolecules
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Intermolecular Forces:
Solubility and Dissociation Solubility: ability of one
substance to dissolve inanother
For example, sugar or salt
dissolves in water DissociationorSeparation: in
ionic compounds, cations areattracted to negative end andanions attracted to positive end
of water molecules; the ionsseparate and each becomessurrounded by watermolecules
Electrolyte: dissociation of anionic compound in water
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Electrolytes and Nonelectrolytes
Electrolytes: solutions made by thedissociation of cations (+) and anions (-) in
water
Have the capacity to conduct an electric currentCurrents can be detected by electrodes
Nonelectrolytes: solutions made by
molecules that dissolve in water, but do notdissociate; do not conduct electricity
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Chemical Reactions Atoms, ions, molecules or compounds interact
to form or break chemical bondsReactants: substances that enter into a chemical
reaction.
Products: substances that result from the reaction
Chemical bonds are made (synthesis;anabolism) and broken (decomposition;catabolism) during chemical reactions
Metabolism: collective term used for the sumof all of the anabolic and catabolic reactions inthe body
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Synthetic Reactions Two or more reactants chemically combine to form a new
and larger product. Anabolism. Chemical bonds made; energy stored in the bonds.
Responsible for growth, maintenance and repair
Hydrolysis: synthetic reaction where water is a product
Produce chemicals characteristic of life: carbohydrates, proteins,lipids, and nucleic acids
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Decomposition Reactions A large reactant is broken down to form smaller products.
Catabolism. Chemical bonds broken; energy released.
Hydrolysis: water is split into two parts that contribute to the formation ofthe products
Example: the breakdown of ATP to form ADP and inorganic phosphatewith a concomitant release of free energy
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Reversible Reactions
Chemical reactions in which the reaction
can proceed either from reactants to
products or from products to reactants. Equilibrium: rate of product formation is
equal to rate of reactant formation
Example: CO2 and H+ formation in plasma
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Oxidation-Reduction Reactions
Oxidation: lossof an electron by an atom
Reduction:gainof an electron by an atom
Oxidation-Reduction Reactions: the
complete or partial loss of an electron byone atom is accompanied by the gain of thatelectron by another atom
Synthetic/decomposition reactions can beoxidative reduction reactions
Reactions can be described in more than oneway
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Energy: the capacity to do work
Potential Energy: energy stored in chemicalbonds; energy that could do work if it were
released. Breaking chemical bonds releases energy.
Kinetic Energy: does work and moves matter Mechanical Energy: energy resulting from the
position or movement of objects
Chemical Energy: form of potential energy in the
chemical bonds of a substance
Heat Energy: energy that flows between objects of
different temperatures
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ATP and Potential Energy
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Heat Energy
When a chemical bond is broken and
energy is released, only some of that energy
is used to manufacture ATP. Energy that is released but not captured is
released as heat.
The heat used by humans to maintain bodytemperature.
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Speed of Chemical Reactions
Temperature affects rate of reaction. Increase in temperature means increase of kinetic energy.
Molecules move faster, collide harder and more frequently.
Concentration of reactants. As concentration of reactants increases, rate of reaction increases.
A decrease of O2 in cells can cause death as rate of aerobic
chemical reactions decreases.
Catalysts: substances that increase the rate of chemical
reactions without being permanently changed or depleted Enzymes: proteinaceous catalysts that increase the rate of chemical
reactions by lowering the activation energy necessary for reactionto begin
Activation Energy: minimum energy reactants must have to start achemical reaction
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Activation Energy and Enzymes
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Chemistry
Inorganic Chemistry: generally,
substances that do not contain carbon
Water, oxygen
Exceptions: CO, CO2, and HCO3-
Organic Chemistry: study of carbon-
containing substances. Those that arebiologically active are called biochemicals.
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Water
High specific heat: large amount of heatrequired to raise temperature of waterStabilizes body temperature
ProtectionLubricant, cushion
Participates in chemical reactions
Many reactions take place in waterDehydration and hydrolysis
Serves as a mixing medium
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Mixtures, Solutions and Measures of Concentration
Mixture: substances physically but not chemically
combined Suspension: materials separate unless stirred. Sand and
water.
Colloid: dispersal of tiny particles through a medium. Milk.
Solution: mixture of liquids, gasses, or solids that areuniformly distributed and chemically combined Solvent: that which dissolves the solute
Solute: that which dissolves in the solvent
Concentration: measure of number of particles ofsolute per volume of solution Unit used by physiologists is osmolality
Concentration of body fluids influences movement of fluidinto and out of cells.
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Acids and Bases; Salts and Buffers
Acid: a proton donor or any substance thatreleases hydrogen ions
Base: a proton acceptor or any substance
that binds to or accepts hydrogen ions Salt: a compound consisting of a cation
other than a hydrogen ion and an anion other
than a hydroxide ion. Example: NaCl Buffer: a solution of a conjugate acid-base
pair in which acid and base components
occur in similar concentrations
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The pH Scale
Refers to the Hydrogenion concentration in a
solution
Neutral: pH of 7 or equal
hydrogen and hydroxideions
Acidic: a greater
concentration of
hydrogen ions Alkaline or basic: a
greater concentration of
hydroxide ions
O d C b Di id
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Oxygen and Carbon Dioxide:
Important Inorganic Compounds
Oxygen (O2): required in the final step in
the series of reactions used to extract energy
from food.
Carbon dioxide (CO2): produced during the
catabolism of organic compounds.
Metabolic waste product.
Combines with water in plasma and forms H+
thus affecting acid/base balance
O i Ch i Bi h i l
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Organic Chemistry: Biochemicals
Carbohydrates: composed of carbon, hydrogen, oxygen. Divided into monosaccharides, disaccharides, polysaccharides
Example: glucose Energy sources and structure
Lipids: composed mostly of carbon, hydrogen, oxygen. Relatively insoluble in water.
Example: anabolic steroids Functions: protection, insulation, physiological regulation, component ofcell membranes, energy source
Proteins: composed of carbon, hydrogen, oxygen, nitrogen,sometimes iodine.
Example: insulin Functions: regulate processes, aid transport, protection, muscle contraction,
structure, energy
Nucleic Acids: composed of carbon, hydrogen, oxygen, nitrogen,phosphorus.
Examples: ATP, DNA, RNA
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Carbohydrates: Monosaccharides
Simple sugars.
Six-carbon sugars like
glucose, fructose, andgalactose are
important in the diet as
energy sources.
Five-carbon sugars are
components of ATP,
DNA and RNA
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Carbohydrates: Disaccharides
Two simple sugars
bound together by
dehydration Examples: sucrose,
lactose, maltose
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Carbohydrates: Polysaccharides
Long chains of manymonosaccharides.
Storage molecules formonosaccharides andform part of cell surface
markers Glycogen formed by
animals.
Starch and celluloseformed by plants Starch in food is used as a
source of monosaccharides
Cellulose in food acts asfiber (bulk) in the diet
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Lipids: Fats
Ingested and broken
down by hydrolysis Triglycerides:
composed of glycerol
and fatty acids
Functions: protection,insulation, energy
source
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Lipids: Phospholipids
Polar (hydrophilic) at
one end; nonpolar
(hydrophobic) at the
other.
Function: important
structural component
of cell membranes
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Lipids: Steroids
Cholesterol, bile
salts, estrogen,
testosterone. Carbon atomsarranged in four rings
Functions:
physiologicalregulators and
component of cell
membranes
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Lipids: Eicosanoids and
Fat-soluble Vitamins
Eicosanoids: Derived from fatty acids.
Function: Important regulatory molecules
Fat-soluble Vitamins: nonpolar molecules
essential for normal functioning.
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Proteins
Amino acids: buildingblocks of protein
Peptide bonds:covalent bonds formedbetween amino acidsduring protein
synthesis
E P t i C t l t
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Enzymes: Protein Catalysts Lower the activation energy necessary
for a reaction to occur; bring reactants
into close proximity Three-dimensional shape contains an
active site where reactants attach.
Induced Fit Hypothesis: enzymeschange shape to accommodate the shapeof specific reactants
Enzyme names usually end in ase andoften have the same word stem as thereactant; for example a lipid is a
reactant for lipase. Cofactors: combine with active site and
make nonfunctional enzymes functional
Organic cofactors called coenzymes
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Nucleotides
Composed of a five-carbon sugar, a
nitrogenous base, and a phosphate Include the nucleic acids (DNA and RNA)
and ATP
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DNA: Deoxyribonucleic acid
Genetic material ofcells copied from onegeneration to next
Composed of 2 strandsof nucleotides Each nucleotide
contains one of theorganic bases ofadenine or guanine(which are purines)and thymine orcystosine (which are
pyrimidines).
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RNA: Ribonucleic acid
Similar to a single strand of DNA
Four different nucleotides make up organic
bases except thymine is replaced with uracil(pyrimidine)
Responsible for interpreting the code within
DNA into the primary structure of proteins.
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Adenosine Triphosphate (ATP)
Energy currency of the body
Provides energy for other chemical reactions as anabolismor drive cell processes as muscle contraction
All energy-requiring chemical reactions stop when there isinadequate ATP