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BIOL 211 Introduction to Cell & Molecular Biology Dr. Jon Atwater. http://www.swccd.edu/~biotechnology. LIFE HAS A HIERARCHY OF ORGANIZATION. Emergent Properties at each level of complexity. Each level encompasses a specialized area of research.
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BIOL 211 Introduction to Cell & Molecular Biology Dr. Jon Atwater http://www.swccd.edu/~biotechnology
LIFE HAS A HIERARCHY OF ORGANIZATION • Emergent Properties at each level of complexity. • Each level encompasses a specialized area of research. • By learning about “the parts”, we hope to gain an understanding of “the whole”. This is reductionism. • Systems Biology
The functional and structural molecules of cells- Large molecules called “Macromolecules” • Nucleic Acids (DNA and RNA) • Proteins • Carbohydrates • Lipids
Bio-Ethics We must use our knowledge wisely!
CHEMISTRY REVIEW Ultimately, life is reduced to a bunch of molecules of matter, so let’s start at the beginning.
Electron Energy Levels (Electron Shell) -Potential energy correlates with distance from nucleus.
Electron configurations of the first 18 elements Electrons in outermost shell are called “valence electrons”. Atoms with same number of valence electrons have similar chemical behavior. Filled outer shell- Unreactive Partially filled outer shell- Reactive.
CHEMICAL BONDING 1. Covalent Bonds (Strong chemical bond, not easily broken)
Electronegative atoms covalently bonded to less electronegative atoms, results in Polar covalent bonding.
2. Ionic Bonds (Weak attraction, broken by water) Gain or loss of electrons to achieve zero valence.
3. Hydrogen Bonding (Weak charge attraction between molecules with polar covalent bonds, ie – attraction between water molecules)
4. Van der Waals interactions (very weak), due to transient charge accumulations.
When covalent bonds form, orbitals hybridize. Sp3 hybridization A MOLECULES BIOLOGICAL FUNCTION IS RELATED TO ITS SHAPE!
THE IMPORTANCE OF WATER TO LIFE! -Without water life (as we know it) would not exist! -Water is a simple compound with many unique properties important for sustaining life. -These unique properties are due to the polarity of the water molecule.
Water naturally occurs in all 3 physical states on Earth; gas, liquid and solid. -Water moderates temperatures on Earth -High specific heat: acts as “heat sink”. -High heat of vaporization -High heat of fusion
Water: The “universal solvent” “Hydration shell”
Water can dissociate into it’s ions: H2OH+ + OH- [10-7M] [10-7M] The Ion Product of water ([H+] x [OH-]) is always 10-14 This is the basis for the pH scale.
Definitions: Acid: A substance that increases the [H+] in aqueous solution. Ex. HCl H+ + Cl- (strong acid) H2CO3 H+ + HCO3- (weak acid) Base: A substance that reduces the [H+] in aqueous solution. Ex. NaOH Na+ + OH- (strong base) NH3 + H+ NH4+ (Weak base)
Substances that effect the [H+] or [OH-] result in a shift in the equilibrium of water dissociation. Ex. If HCl is added to water to make 1M HCl HCl [H+] + [Cl-] 1M 1M Ion product = 10-14 = 1M x [OH-], [OH-] = 10-14M Or, if NaOH were added to bring the [OH-] to say 10-3M, then the [H+] would be 10-11M (10-3M x 10-11M = 10-14M) The pH scale was invented to simplify the expression of these concentrations. pH = -log [H+] Ex. If [H+] = 10-7, pH = -log 10-7 = 7
Food we ingest and metabolic products in our cells can be acidic or basic, so how is pH controlled in our bodies?
BUFFERS! Buffers: Substances that accept or donate H+ in solution stabilizing the pH. Weak acids and weak bases can act as buffers: Ex. H2CO3 HCO3- + H+ Response to rise in pH Response to drop in pH (increase in H+) If buffering capacity is overwhelmed, and physiological pH is altered, it can mean death to an organism.
Sulfur oxides and nitrogen oxides and CO2 dissolve in water to form acids - acid precipitation.
