Chemistry-Basics-for

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Transcript Chemistry-Basics-for

What is the chemical basis of life?
• What are some of the
ideas central to the
chemistry of life?
• (Key concepts of the
chemical basis of life)
How does water do all this?
What allows water to facilitate life at the
cellular and global level?
Hydrogen Bonds
• A weak force of attraction between the H
on one molecule and a highly
electronegative atom on another molecule
Extraordinary Properties of Water
• Versatile Solvent-------due to polarity
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Adhesion and Cohesion---due to H bonds
High Specific Heat --------due to H bonds
High Heat of Vap. ---------due to H bonds
Expands when freezing ---due to H bonds
Ideas central to the chem of life
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Based on covalent bonding
Carbon is the “backbone” of biomolecules
Simple building code
Variation on common theme in extreme
Only 4 fundamental types of biomolecules
Enzymes make and break the covalent bonds in
the chemical reactions in the cell
• Isomers and polymers
• Condensation and Hydrolysis
Famous ions in Biology
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Hydronium H3O+ and Hydroxide OHPotassium K+ ions
Sodium Na+ ions
Calcium Ca2+ ions
Hydrogen H+ ions (protons)
pH SCALE
• measures degree of
alkalinity or acidity
• Ranges from 0 to 14
• 0 – 6 acid
• 7 neutral
• 8-14 base
ACIDS & BASES
• Acids: always (almost) begin with "H"
because of the excess of H+ ions
(hydrogen)
– Ex: lemon juice (6), stomach acid (1.5), acid
rain (4.5), normal rain (6)
• Facts about Acids
• Acids usually taste SOUR/BITTER.
• You eat acids daily (coffee, vinegar,
soda, spicy foods, etc…)
ACIDS & BASES
• Bases: always (almost) end with -OH
because of the excess of hydroxide ions
(Oxygen & Hydrogen)
– EX: oven cleaner, bleach, ammonia, sea water,
blood
• Facts about Bases
• Bases usually feel SLIPPERY to touch and
taste BITTER.
Elements Essential to Life
• About 25 of the 92
natural occurring
elements are essential
to life
• CHON = 96% liv mat
• CHONPS = > 99%
Review of Chemical Equation
Example:
H2O + CO2  H2CO3
reactants
products
A continuum view of bonding
• Atoms complete their valence shell in a
continuum of:
• Nonpolar covalent with equal sharing of e– Examples:
H—H
O=O
• Polar covalent, unequal sharing of e– Examples:
H2O
NH3
• Ionic, with complete transfer of e– Examples:
NaCl
Al2O3
Weak Bonds are Bio’ly Important
• H bonds, hydrophobic interactions, etc
• Can form between different parts of a
single large molecule or between
molecules
• Help stabilize 3D shape of proteins & Nas
• Function in chemical signaling
• Hold enzymes to substrates
Biological Building Codes
• Covalent Bond=
shared pair of
electrons between 2
nonmetals
• H, 1 unpaired e• O, 2 unpaired e• N, 3 unpaired e• C, 4 unpaired e-
Versatility of Carbon
• 4 valence electrons
• Compatibility with many
different elements
• Forms single, double or
triple bonds
• Makes large, complex
molecules possible
– Strait chains
– Branched chains
– Rings
• (poly = many; mer = part)
• Large molecules
consisting of many
similar subunits
connected together
• Monomer = subunit or
building block of polymer
Macromolecules are Polymers
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Carbohydrates = polymer of monosaccharides
Lipids = polymer of fatty acids & glycerol
Proteins = polymer of amino acids
Nucleic Acids = polymer of nucleotides
Polymers & Molecular Diversity
• Unity in life: Only about 40 or 50 common
monomers build macromolecules
• Diversity in life: New properties emerge
when these monomers are arranged in
different ways
Sucrose Synthesis
Hydrolysis
Making & Breaking Polymers
animation
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Dehydration synthesis
Link monomers
Via removal of H2O
1 water per link (out)
One monomer lose
OH, other loses H
• Any assembling of
molecules in cells
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Hydrolysis
Disassemble polymers
Via addition of H2O
1 water per link (in)
One monomer gains
OH, other gains H
• Any disassembly of
molecules in cells