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Transcript
Anatomy and Physiology, Sixth Edition
Rod R. Seeley
Idaho State University
Trent D. Stephens
Idaho State University
Philip Tate
Phoenix College
Chapter 02
Lecture Outline*
*See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes.
2-1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 2
The Chemical Basis of Life
2-2
Basic Chemistry
• Matter, Mass, and Weight
– Matter: Anything that occupies space and has
mass
– Mass: The amount of matter in an object
– Weight: The gravitational force acting on an
object of a given mass
• Elements and Atoms
– Elements: The simplest type of matter with
unique chemical properties
– Atoms: Smallest particle of an element that has
chemical characteristics of that element
2-3
Atomic Structure
• Atoms: composed of
subatomic particles
– Neutrons: no electrical
charge
– Protons: positive charge
– Electrons: negative charge
• Nucleus
– Formed by protons and
neutrons
– Most of volume of atom
occupied by electrons
2-4
Atomic Number and Mass Number
• Atomic Number: Equal to number of protons in each
atom which equals the number of electrons
• Mass Number: Number of protons plus number of
neutrons
2-5
Isotopes and Atomic Mass
• Isotopes: Two or more forms of same element with
same number of protons and electrons but different
neutron number
– 3 types of hydrogen
– Denoted by using symbol of element preceded by mass
number as 1H, 2H, 3H
• Atomic Mass: Average mass of naturally occurring
isotopes
2-6
Electrons and Chemical Bonding
• Ion: When an atom loses or gains electrons and
become charged
– Cation: Positively charged ion
– Anion: Negatively charged ion
• Ionic Bonding
– Cations and anions are attracted to each other
2-7
Covalent Bonding
• Atoms share one or more
pairs of electrons
– Single covalent: Electron
pair between 2 atoms
– Double covalent: Two
atoms share 4 electrons
• Nonpolar covalent:
Electrons shared equally
• Polar covalent: Electrons
not shared equally
2-8
Molecules and Compounds
• Molecules: Two or more atoms chemically
combine to form and independent unit
– Example: Water
• Compounds: A substance composed of two
or more different types if atoms chemically
combined
– Example: Hydrogen Molecule
• Molecular Mass: Determined by adding up
atomic masses of its atoms or ions
– Example: NaCl (22.99 + 35.45)
2-9
Intermolecular Forces
• Result from weak electrostatic attractions
between oppositely charged parts or
molecules, or between ions and molecules
• Weaker than forces producing chemical
bonding
2-10
Intermolecular Forces
• Hydrogen Bonds
– Water: Positively
charged hydrogen
atoms bond with
negatively charged
oxygen atoms of other
water molecules
– Important role in
determining shape of
complex molecules
2-11
Intermolecular Forces
• Solubility: Ability of one substance to dissolve in another
– Example: Sugar dissolves in water
• Dissociation or Separation
– Ionic compounds
– Cations are attracted to negative end and anions attracted to
positive end of water molecules
2-12
Intermolecular Forces
• Electrolytes: Cations (+) and anions (-) that
dissociate in water
– Capacity to conduct an electric current
– Currents can be detected by electrodes
• Nonelectrolytes: Molecules that do not
dissociate form solutions that do not
conduct electricity
2-13
Chemical Reactions
• Chemical Reactions: Atoms, ions,
molecules or compounds interact to form or
break chemical bonds
– Metabolism: All anabolic and catabolic
reactions in the body
• Catabolism: Decomposition reactions
– Hydrolysis: Reactions that use water
• Anabolism: Growth, maintenance, and repair of the
body in synthesis reactions
– Produce molecules characteristic of life: ATP, proteins,
carbohydrates, lipids, and nucleic acids
2-14
Synthesis and Decomposition Reactions
• Synthesis Reactions
– Two or more reactants
chemically combine to
form a larger product
– Anabolism: All body’s
synthesis reactions
• Decomposition Reactions
– Reverse of synthesis
reactions
– Catabolism: Reactions
of decomposition in
body
2-15
Oxidation-Reduction Reactions
• Oxidation
– Loss of an electron by an atom
• Reduction
– Gain of an electron by an atom
• Oxidation-Reduction Reactions
– The complete or partial loss of an electron by
one atom is accompanied by the gain of that
electron by another atom
2-16
Energy
• Energy: The capacity to do work
– Potential Energy: Stored 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
2-17
Energy and Chemical Reactions
2-18
Speed of Chemical Reactions
• Activation Energy: Minimum energy reactants
must have to start a chemical reaction
– Catalysts: Substances that increase the rate of chemical
reactions without being permanently changed or
depleted
– Enzymes: Increase the rate of chemical reactions by
lowering the activation energy necessary for reaction to
begin
2-19
Activation Energy and Enzymes
2-20
Chemistry
• Inorganic Chemistry: Generally substances
that do not contain carbon
– Water
– Oxygen
• Organic Chemistry: Study of carboncontaining substances
2-21
Water
•
•
•
•
Inorganic
Stabilizes body temperature
Protection
Necessary for many chemical reactions of
life
• Mixing Medium
– Mixture: Substance physically but not
chemically combined
• Solution: Liquid, gas, or solid uniformly distributed
– Solvent: What dissolves the solute
– Solute: What is to be dissolved
2-22
Acids and Bases; Salts and Buffers
• Acid: A proton donor or any substance that
releases hydrogen ions
• Bases: A proton acceptor or any substance
that binds to or accepts hydrogen ions
• Salts: A cation consisting of other than a
hydrogen ion and other than an anion or
hydroxide ion
• Buffers: A solution of a conjugate acid-base
pair in which acid and base component
occur in similar concentrations
2-23
The pH Scale
• Refers to the Hydrogen
ion concentration in a
solution
– Neutral: pH of 7 or
equal hydrogen and
hydroxide ions
– Acidic: a greater
concentration of
hydrogen ions
– Alkaline or basic: a
greater concentration of
hydroxide ions
2-24
Organic Chemistry
• Carbohydrates
– Composed of carbon, hydrogen, oxygen
• Lipids
– Composed mostly of carbon, hydrogen, oxygen
• Proteins
– Composed of carbon, hydrogen, oxygen,nitrogen
• Nucleic Acids: DNA and RNA
– Composed of carbon, hydrogen, oxygen, nitrogen, phosphorus
• Adenosine Triphosphate (ATP)
– Composed of adenosine and three phosphate groups
2-25
Carbohydrates
• Monosaccharides
– Simple sugars: glucose, fructose, galactose
• Disaccharides
– Two simple sugars bound together by
dehydration: sucrose, lactose, maltose
• Polysaccharides
– Long chains of many monosaccharides:
glycogen in animals; starch and cellulose in
plants
2-26
Monosaccharides
2-27
Disaccharide and Polysaccharide
2-28
Lipids
• Lipids: Can be dissolved in nonpolar organic
solvents as alcohol or acetone but relatively
insoluble in water
– Fats: Ingested and broken down by hydrolysis
– Triglycerides: composed of glycerol and fatty acids
– Phospholipids: Important structural component of
cell membranes
– Eicosanoids: Derived from fatty acids
– Steroids: Cholesterol, bile salts, estrogen,
testosterone
– Fat-soluble Vitamins
2-29
Phospholipids
2-30
Steroids
2-31
Proteins
• Amino acids: The building blocks of protein
• Peptide bonds: Covalent bonds formed
between amino acids during protein synthesis
• Structure
– Primary, secondary, tertiary, quartenary
• Enzymes: Protein catalysts
–
–
–
–
Lock-and-key model
Active site
Cofactors
Coenzymes
2-32
Peptide Bonds
2-33
Protein Structure and Enzyme Action
2-34
Nucleic Acids: DNA and RNA
• DNA: Deoxyribonucleic acid
– Genetic material of cells copied from one
generation to next
– Composed of 2 strands of nucleotides
• Each nucleotide contains one of the organic bases of
adenine or guanine which are purines and thymine or
cystosine which are pyrimidines
• RNA: Ribonucleic acid
– Similar to a single strand of DNA
• Four different nucleotides make up organic bases
except thymine is replaced with uracil (pyrimidine)
2-35
DNA Structure
2-36
Nucleotides and Nitrogenous Bases
2-37
Adenosine Triphosphate (ATP)
• Energy currency of the body
• Provides energy for other chemical reactions as anabolism or
drive cell processes as muscle contraction
• All energy-requiring chemical reactions stop when there is
inadequate ATP
2-38