Download - Chapter2a
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Chapter 2: Chemistry
Comes Alive
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Why Chemistry???
• Chemistry is everywhere, especially within the human body
• Chemistry drives biological processes
• We are composed of chemicals (water, protein, fat, DNA, etc) and the substances we ingest are chemicals as well
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Structural Organization: Chemical Level
• Atoms/ Elements
• Molecules/
Compounds
• Macromolecules
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Basic Chemistry: Matter
• Chemistry is the study of the composition of matter and how this composition changes through chemical reactions
• Matter is anything that occupies space and has mass
• Matter exists in solid, liquid, and gaseous states
• Within the body, all states or matter are evident
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Basic Chemistry: Energy
• Energy is the capacity to do work or to put matter into motion
• Kinetic Energy = energy in action
• Potential Energy = stored energy
• Energy form conversions: 1st law of thermodynamics…
“Neither matter nor energy can be created or destroyed”
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Forms of Energy
• Chemical: Stored in chemical bonds (ex: ATP)
• Electrical: From the movement of charged particles (ex: nerve impulses)
• Mechanical: Energy directly involved in moving matter (ex: muscular contraction)
• Radiant/ Electromagnetic: Energy that travels in waves (ex: Light, UV, X-rays)
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Composition of Matter
• All matter is composed of elements
• Each element is composed of atoms
• Each element is has unique physical & chemical properties
• Most important for the body = CHNOPS
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Atomic StructureSubatomic
ParticleCharacteristics
Proton + charge, large particle, in nucleus
Electron - charge, small particle, around nucleus
Neutron No charge, large particle, in nucleus
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Atoms of Elements
• Atomic Number = p+
• p+ = e-
• Mass Number = p+ + no
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Chemical Bonding
• e- are arranged in shells & orbitals
• Valence shell electrons affect the reactivity of atoms
• Octet rule
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Molecules & Compounds
• Molecules = two or more chemically bound atoms
• Two or more atoms of the same element (ex: H2, O2) = molecule of an element
• Two or more atoms of different elements (ex: H2O, NaCl) = molecule of a compound
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Ionic Bonds
• e- can transfer & result in ion (charged) formation• Anions: Negatively charged ion, e- acceptor (Cl-)• Cations: Positively charged ion, e- donor (Na+)• Since opposites attract, the atoms stay close
together
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Covalent Bonds
• e- are shared in order to fill valence shells part-time• Covalent bonds involve a shared orbital
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Polarity
• Nonpolar Covalent Molecules:– Have equal e- pair
sharing– Charge is balanced
among atoms
• Polar Covalent Molecules:– Unequal sharing of e-
– Slight (–) charge on one end, slight (+) charge on another
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Hydrogen Bonds
• Occur when covalently bonded H atoms are weakly attracted by other atoms
• Not a true bond but is a weak attraction
• Important for DNA structure
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Chemical Reactions• Chemical equations symbolize chemical
reactions• Components: Products & Reactants• Synthesis: A + B AB• Decomposition: AB A + B• Exchange: AB + C AC + B AB + CD AD + CB
• Some reactions are reversible A + B AB
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Examples
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Factors Affecting Reaction Rates
• Temperature:
Increased = Faster
Decreased = Slower
• Reactant Concentration:
High = Faster
Low = Slow
• Particle Size:Small = Fast
Large = Slow
• Catalysts:Present = Fast
Absent = Slow
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Biochemistry
• Biochemistry: The study of the chemical composition and reactions of living matter
• Inorganic Compounds: All compounds that do not contain carbon (water, oxygen, salts)
• Organic Compounds: All compounds that contain carbon (carbohydrates, lipids, proteins, nucleic acids)
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Inorganic Compounds: Water
• Most abundant cellular component
• High heat capacity• High heat of vaporization• Universal solvent• Forms hydration layers• Transports biochemicals• Reactive• Cushions
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Inorganic Compounds: Salts
• Ionic compounds that do not contain H+ or OH-
• In water, dissociate into ions/ electrolytes
• Ions are essential for:– Nerve impulse
transmission (Na, K)– Muscle contraction (Na,
K)– Hemoglobin in blood (Fe)
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Inorganic Compounds: Acids & Bases
• Acids: Donate (release) H+/ protons– When dissolved in water, acids release H+ and
an anion HCL H+ + Cl-
• Bases: Accept H+, commonly contain OH-
– When dissolved in water, bases release OH- and a cation. The OH- ion then immediately accepts H+ to form water
NaOH Na+ + OH-
OH- + H+ H2O
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pH Scale
• Measures H+ ion concentrations
• Acidic:
[H+] > [OH-], pH= 0-6
• Neutral:
[H+] = [OH-], pH= 7
• Basic/ Alkaline:
[H+] < [OH-], pH= 8-14
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Inorganic Compounds: Buffers
• Buffers: Chemicals that resist abrupt pH changes
– Function by donating H+ when needed and by accepting H+ when in excess
– Very, very important for biological systems!!!
H2CO3 HCO3- + H+
weak acidH+ Donor
weak baseH+ Acceptor
Proton
Rising pH
Drop in pH
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Organic Compounds
• Molecules unique to biological systems– Carbohydrates
– Lipids (fats)
– Proteins
– Nucleic Acids (DNA & RNA)
• Monomer, Dimer, Polymer
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Building & Breaking Organic Compounds
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Polymerization
• Chain-like molecules composed of monomeric units
• Continuous dehydration synthesis can grow polymer chains