A GOAL OF HUMAN BIOLOGY (of College Courses)

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A GOAL OF HUMAN BIOLOGY(of College Courses)

• Paradigm shift!!!
• From a teaching environment . . . . .
• To a learning environment.
• Biology is primarily about
• Not memorization . . . . .
• BUT understanding . . . . .
• and application (practical application) . . . .
  . . . . .

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Learning for Understanding and Retention

• Critical Thinking Skill 1
• 1. Summarize or restate in your own words.
• 2. Elaborate on the main idea.
• 3. Give examples to support or clarify.
• 4. Relate the issue/content/skill to life or
  other concepts.

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Chapter 2

• Chemistry of Life

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Outline

• FOCUS on now.
• Basic Chemistry
• Atoms
• Isotopes
• Molecules and Compounds
• Chemical Reactions
• Properties of Water
• Acids and Bases
• FOCUS on with Digestive System (Ch. 5)
• Macromolecules
• ATP

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Basic Chemistry

• Life is chemistry.
• Chemistry is the study of matter and the changes
  it undergoes.
• There are 92 naturally-occurring elements.
• Their characteristics are represented in the
  Periodic Table of Elements.
• Over 90 of human body is composed of four
  elements.
• Carbon.
• Nitrogen.
• Oxygen.
• Hydrogen.

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Atoms

• An atom is the smallest unit of matter that
  retains an elements physical and chemical
  properties.
• Positively-charged protons and neutral neutrons
  are located in the nucleus.
• Negatively-charged electrons orbit the nucleus in
  shells (energy levels).
• How many will each hold?
• 2, 8, 18, 32, . . . .
• Octet Rule?

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Atoms

• An elements atomic number is designated by its
  number of protons.
• An elements atomic weight is designated by its
  protons and neutrons.
• Why not include the electrons?

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Isotopes

• Isotopes are atoms of the same element that
  differ in the number neutrons, or a different
  atomic weight.
• A radioactive isotope spontaneously decays,
  giving off rays and subatomic particles.
• Can be used as a tracer to detect molecular
  changes.
• Radiation kills healthy cells, but can also be
  used to kill cancerous cells.

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Use of Radiation to Study the Brain
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Molecules and Compounds

• A molecule is a group of atoms of the same
  element bonded together.
• A compound is a group of atoms of different
  elements bonded together.
• Why do atoms bond together?
• To achieve stability. . . . . Octet Rule.

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Ionic Reactions

• During an ionic reaction, atoms give up or take
  on an electron (transfer electrons) to stabilize
  their outer shells.
• Ions are particles that carry a positive () or
  negative (-) charge because they have transferred
  electrons to form a bond.
• The attraction between oppositely charged sodium
  ions and chloride ions forms an ionic bond.

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Ionic Reaction
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Covalent Reactions

• In covalent reactions, atoms share electrons in
  covalent bonds instead of losing or gaining them.
• A single bond is formed when atoms share a single
  pair of electrons.
• A double bond is formed when atoms share two
  pairs of electrons.
• A triple bond is formed when atoms share three
  pairs of electrons.

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Water and Living Things

• The electrons in water spend more time circling
  the larger oxygen atom than the smaller hydrogen
  atom.
• Water is a polar molecule with the oxygen end
  being slightly negative and the hydrogen end
  being slightly positive.
• A hydrogen bond occurs when a covalently bonded
  hydrogen is positive and is attracted to a
  negatively charged atom.

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Hydrogen Bonding between Water Molecules
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Properties of Water

• Water is liquid at room temperature.
• Water is a solvent for polar molecules.
• Water molecules are cohesive.
• Water temperature rises and falls slowly.
• Water has a high heat of vaporization.
• Frozen water is less dense than liquid water.

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Acids and Bases

• Acids dissociate in water and release hydrogen
  ions (H).
• Bases take up hydrogen ions (H) or release
  hydroxide ions (OH-).
• Buffers help keep the pH within normal limits by
  taking up excess hydrogen ions or hydroxide ions.

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pH Scale

• The pH scale measures acidity or alkalinity of a
  solution.
• Neutral 7.
• Acidic lt 7.
• Basic gt 7.
• Logarithmic Scale.

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MOLECULES OF LIFE

• These molecules will be more significant when we
  study the Digestive System and Nutrition (Chapter
  7)

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Molecules of Life

• Macromolecules?
• Four categories of molecules (based on structure)
  are unique to cells.
• Carbohydrates.
• Lipids.
• Proteins.
• Nucleic Acids.
• Macromolecules are synthesized by a dehydration
  reaction (condensation reaction or dehydration
  synthesis), and degraded or broken down by a
  hydrolysis (hydro / lysis) reaction.

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Carbohydrates

• Carbohydrates (CHO compounds) function for quick
  and short-term energy storage.
• Monosaccharide (simple sugar).
• Glucose.
• Disaccharide.
• Fructose.

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Complex Carbohydrates

• Polysaccharides.
• Starch (plants).
• Glycogen (animals).
• Cellulose (plant cell walls).

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Lipids

• Lipids contain more energy per gram than any
  other biological molecule (2x CHO).
• Do not dissolve in water.
• Absence of polar groups.
• Fats.
• Animal origin, solid at room temperature.
• Oils.
• Plant origin, liquid at room temperature.
• Consist of glycerol and 3 fatty acids.

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Saturated and Unsaturated Fatty Acids

• A fatty acid is a carbon-hydrogen chain ending
  with -COOH.
• Saturated fatty acids contain only single bonds
  between the carbon atoms.
• Unsaturated fatty acids contain one or more
  double bonds in the carbon chain.

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Phospholipids and Steroids

• Phospholipids contain a phosphate head and fatty
  acid tails.
• Are critical in all cell membranes
• Polar head and non-polar tails.
• Soluble in water.
• Steroids are lipids with a backbone of four fused
  carbon rings.
• Estrogen and testosterone.

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Proteins

• Proteins are macromolecules with amino acid
  subunits.
• An amino acid has a central carbon atom bonded to
  a hydrogen and three groups.
• Peptide bond - Any bond joining two amino acids.
• Polypeptide - Single amino acid chain.
• Are structural or enzymatic.

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Levels of Protein Organization

• Primary Structure.
• Linear sequence of amino acids.
• Secondary Structure.
• Polypeptide takes on orientation in space.
• Tertiary Structure.
• Final three-dimensional shape.
• Quaternary Structure.
• Proteins with more than one polypeptide.

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Nucleic Acids

• Nucleic acids are huge macromolecules composed of
  nucleotides.
• A nucleotide is constructed of a phosphate, a
  pentose sugar, and a nitrogenous base.
• Deoxyribonucleic acid (DNA).
• Double-stranded helix.
• The molecule of inheritance.
• Ribonucleic acid (RNA).
• Single stranded.
• A helper to DNA.

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DNA Structure
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(ATP) Adenosine Triphosphate

• ATP is the primary cellular energy carrier.
• Energy currency of cells.
• is a temporary, unstable, energy-storage
  molecule.
• Breaks down to adenosine diphosphate (ADP) and a
  molecule of inorganic phosphate, releasing energy
  to drive cellular metabolism.

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Review

• Basic Chemistry
• Atoms
• Isotopes
• Molecules and Compounds
• Chemical Reactions
• Properties of Water
• Acids and Bases
• Macromolecules
• ATP

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Covalent Reactions
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The pH Scale
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Phospholipids