Predict

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Predict

• Brian overslept and missed breakfast. After his
  900 class, he began to feel a little weak, so he
  bought a supersized Chocochunk bar from a vending
  machine and ate it on the way to his anatomy and
  physiology lab. Brian felt better after eating
  the candy bar, but it barely held him over until
  lunch. The level of sugar in the bloodstream is
  just one of the chemical variables the body
  regulates as it attempts to maintain a relatively
  constant internal environment, called
  homeostasis. After reading about homeostasis in
  this chapter, formulate an explanation for the
  fluctuations that took place in Brians blood
  sugar that morning.

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• The question suggests that homeostasis is
  involved. In addition, the question describes a
  series of events that help formulate an
  explanation Brian doesnt eat breakfast, becomes
  weak later in the morning, then eats a candy bar,
  and as a result, he feels better.
• In chapter 1 we learned that homeostasis is the
  existence and maintenance of a relatively
  constant internal environment. Brian experienced
  weakness due to lack of food eating the candy
  bar made him feel better. This is an example of a
  negative-feedback mechanism where the body
  reduces any deviations from the normal condition,
  or set point. For Brian, the deviation was a drop
  in blood sugar after skipping breakfast.
  Homeostatic blood sugar levels were restored when
  he ate the candy bar.
• But there is more to consider. He didnt feel
  weak until later in the morning. Why the delay?
  Pancreatic hormones maintain blood sugar
  (glucose) levels. When Brian skipped breakfast,
  one hormone caused stored glucose in liver cells
  to be released into the blood to maintain blood
  glucose homeostasis. But the amount of stored
  glucose is limited. Eventually, Brian needed to
  eat to obtain more glucose. After Brian ate the
  candy bar, another pancreatic hormone caused
  cells to take up and store any excess glucose.
  Once blood glucose levels have returned to their
  set point, further secretion of the pancreatic
  hormone is inhibited. Therefore, this negative
  feedback mechanism helps maintain blood glucose.

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Chapter 2 The Chemical Basis of Life
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2.1 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
• 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 of subatomic particles
• Neutrons no electrical charge
• Protons one positive charge
• Electrons one negative charge

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Atomic Number and Mass Number

• Atomic Number equal to number of protons in each
  atom, which is equal to the number of electrons
• Mass Number number of protons plus neutrons

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Isotopes and Atomic Mass

• Isotopes two or more forms of same element with
  same number of protons and electrons but
  different neutron number
• 1H, 2H, 3H
• Atomic Mass average mass of naturally occurring
  isotopes

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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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The Mole and Molar Mass

• Avogadros Number 6.022 x 1023
• Mole Avogadros number of atoms, ions, molecules
• Molar mass mass of one mole of a substance in
  grams, which is equal to its atomic mass units.
• Avogadros number is to the chemist what a dozen
  is to a baker.

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Electrons and Chemical Bonding

• Ionic Bonding atoms exchange electrons
• Covalent Bonding two or more atoms share
  electron pairs
• Ion an atom loses or gains electrons and
  becomes charged
• Cation positively charged ion
• Anion negatively charged ion

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Covalent Bonds

• Atoms share electrons
• Single covalent two atoms share one pair of
  electrons
• Double covalent Two atoms share 4 electrons
• Nonpolar covalent Electrons shared equally
• Polar covalent Electrons not shared equally

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Molecules and Compounds

• Molecules two or more atoms covalently bonded
• Example a hydrogen molecule (H2)
• Compounds a substance composed of two or more
  different types of atoms chemically (ionic,
  covalent, etc.) combined
• Example water (H2O, NaCl)
• 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
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Intermolecular Forces Solubility and
Dissociation

• Solubility ability of one substance to dissolve
  in another
• Dissociation or Separation in ionic compounds,
  cations are attracted to negative end and anions
  attracted to positive end of water molecules the
  ions separate and each becomes surrounded by
  water molecules
• Electrolyte dissociation of an ionic compound in
  water

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Electrolytes and Nonelectrolytes

• Electrolytes solutions made by the dissociation
  of cations () and anions (-) in water
• conduct an electric current
• Nonelectrolytes solutions made by molecules that
  dissolve in water, but do not dissociate do not
  conduct electricity

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2.2 Chemical Reactions and Energy

• Atoms, ions, molecules or compounds interact to
  form or break chemical bonds
• Reactants 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 sum of
  all of the anabolic and catabolic reactions in
  the body

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Synthesis 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
• Dehydration 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 of the products
• Example the breakdown of ATP to form ADP and
  inorganic phosphate with 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

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Oxidation-Reduction Reactions

• Oxidation loss of an electron by a substance
• Reduction gain of an electron by a substance
• Oxidation-Reduction Reactions the complete or
  partial loss of an electron by one substance is
  accompanied by the gain of that electron by
  another substance
• Synthetic/decomposition reactions can be
  oxidation - reduction reactions

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Energy the capacity to do work

• Potential Energy energy stored in chemical
  bonds. Breaking chemical bonds releases energy to
  do work.
• 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.
• body temperature.

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Speed of Chemical Reactions

• Temperature affects rate of reaction.
• Increase in temperature increase of kinetic
  energy.
• Molecules move faster, collide harder and more
  frequently.
• Concentration of reactants.
• As concentration of reactants increases, rate of
  reaction increases.
• O2 in cells
• Catalysts increase the rate of chemical
  reactions without being permanently changed or
  depleted
• Enzymes protein catalysts lower the activation
  energy necessary for reaction to begin
• Activation Energy minimum energy reactants must
  have to start a chemical reaction

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Activation Energy and Enzymes
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2.3 Inorganic Chemistry

• Inorganic Chemistry generally, substances that
  do not contain carbon
• Water, oxygen, calcium phosphate, metal ions
• Exceptions CO, CO2, and HCO3-
• Organic Chemistry study of carbon-containing
  substances. Those that are biologically active
  are called biochemicals.

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Water

• Cohesion and adhesion properties
• 50-60 of body, 92 of blood
• High specific heat large amount of heat required
  to raise temperature of water
• Stabilizes body temperature
• Protection
• Lubricant, cushion
• Participates in chemical reactions
• Many reactions take place in water
• Dehydration and hydrolysis
• Serves as a mixing medium

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Mixing Medium (cont.)

• 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 are uniformly distributed and chemically
  combined
• Solvent that which dissolves the solute (like
  water)
• Solute that which dissolves in the solvent
  (like sugar)
• Blood is a mixture, solution, and colloid.

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Solution Concentrations

• Concentration number of particles of solute per
  volume of solution
• Osmolality number of particles dissolved in one
  kilogram of water
• One osmole is equal to Avogadros number of
  particles in one kilogram of water.
• Unit used by physiologists is milliosmoles
  because of the low concentrations in the human
  body
• Concentration of body fluids influences movement
  of fluid into and out of cells.
• 300 mOsm is average in the human body

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Acids and Bases Salts and Buffers

• Acid a proton donor or any substance that
  releases hydrogen ions (H)
• Base a proton acceptor or any substance that
  binds to or accepts hydrogen ions (OH-)
• 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

• Physiologic pH is 7.4

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Buffers

• Regulate pH
• Important biological buffers
• Bicarbonate-carbonic acid
• Phosphates, protein
• Respiratory (high CO2 acidosis) and renal
  mechanisms

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Oxygen and Carbon Dioxide

• Oxygen (O2) 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

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2.4 Organic Chemistry

• Carbohydrates composed of carbon, hydrogen,
  oxygen.
• Divided into monosaccharides, disaccharides,
  polysaccharides
• Energy sources and structure
• Lipids composed mostly of carbon, hydrogen,
  oxygen.
• Relatively insoluble in water.
• Functions protection, insulation, physiological
  regulation, component of cell membranes, energy
  source
• Proteins composed of carbon, hydrogen, oxygen,
  nitrogen, sometimes iodine.
• 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, and
  galactose 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 many monosaccharides.
• Storage molecules for monosaccharides and form
  part of cell surface markers
• Glycogen formed by animals.
• Starch and cellulose formed by plants
• Starch in food is used as a source of
  monosaccharides
• Cellulose in food acts as fiber (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 Fats

• Fatty acids may be saturated or unsaturated
• Saturated contains all single bonds in the
  carbon chain
• Unsaturated contains one (mono) or more (poly)
  double bonds in the carbon chain
• Better because they do not stick to the inside of
  blood vessels.
• Trans fats unsaturated fats that are
  artificially altered to be more saturated. Are
  the highest CV risk fat.

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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 Eicosanoids and Fat-soluble Vitamins

• Eicosanoids Derived from fatty acids.
• Function Important regulatory molecules
• Include thromboxanes, leukotrienes, and
  prostaglandins
• Fat-soluble Vitamins nonpolar molecules
  essential for normal functioning.

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Lipids Steroids

• Cholesterol, bile salts, estrogen, testosterone.
• Carbon atoms arranged in four rings
• Functions physiological regulators and component
  of cell membranes

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Proteins

• Amino acids building blocks of protein
• Peptide bonds covalent bonds formed between
  amino acids during protein synthesis

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Protein Structure
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Protein Structure
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Enzymes

• Lower the activation energy necessary for a
  reaction to occur bring reactants into close
  proximity
• active site where reactants (substrates) attach.
• Induced Fit Hypothesis enzymes change shape
• ase 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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Nucleic Acids DNA and RNA

• 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 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).

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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
  anabolism or drive cell processes as muscle
  contraction
• All energy-requiring chemical reactions stop when
  there is inadequate ATP