Post on 18-Dec-2015
DEFINITIONS
MATTER- Has weight & occupies space- Composed of elements
ELEMENT- Simplest chemical substance with unique
chemical properties- 92 natural- 26 in humans
ELEMENT continued
- 96% (body weight)* Hydrogen* Oxygen* Carbon* Nitrogen
- Each element composed of similar atoms
ATOMS
Smallest unit of element, retaining the chemical characteristics of that element
Smallest unit in chemical reactionsSmallest structural unit in our bodiesSubatomic particles:
- Proton* Positive charge* Weighs one atomic unit
ATOMS continued
- Neutron* No charge* One atomic unit
- Electron* Negative charge* No significant weight
ATOMS continued
Atomic number- Number of protons in atom
Atomic weight- Sum of proton & neutrons
Atomic symbol- Each element represented by letter(s)
ATOMIC ARRANGEMENT
Central nucleus of protons & neutronsElectrons in orbitals (shells)Inner orbital “full” with 2 electronsSecond orbital holds up to 8Third orbital holds 18Valence = outermost orbital with any
electrons
ATOMIC ARRANGEMENT continued
The number of valence electrons affects atomic reactivity- Stable if valence is full- Reactive/unstable if incomplete valence
Atoms can:- Gain/lose electrons- Lose excess neutrons (Radioactive Isotopes)- Protons are NEVER lost or gained
MORE DEFINITIONS
Molecule- Two or more atoms bonded together (O2)
Compound- Two or more elements in a fixed ratio (H2O)
Chemical Formula- Indicates number of atoms of each element
in a molecule (CO2)
CHEMICAL BONDS
Join atoms by valence electronsElectrons gained, lost or shared to fill
valence3 Types:
- Ionic or Electrovalent- Covalent- Hydrogen
CHEMICAL BONDS continued
IONIC BONDS- Transfer of electrons between atoms- Atoms that GAIN electrons have a net
negative charge (anion)- Atoms that LOSE electrons have a net
positive charge (cation)- Oppositely charged ions are mutually
attractive- Common in inorganic molecules
CHEMICAL BONDS continued
COVALENT BONDS- Electrons shared between atoms- Common in organic molecules
Chemical bonds represent STORED ENERGY- Bond formation requires energy- Energy is released when bonds are broken
CHEMICAL BONDS continued
HYDROGEN BONDS- Form weak attraction within or between
polar molecules- Involves association between slightly
positive H and two other atoms (slightly negative O or N)
- Easily broken by Temp or pH
- Found in: H2O, Proteins, Nucleic Acids
CHEMICAL REACTIONS
SYNTHESIS- A + B AB- Form bond, requires energy- Dehydration Synthesis
* Water released as bond formed
* E.g. Glycogen from glucose
CHEMICAL REACTIONS continued
DECOMPOSITION- AB A + B- Breaks bonds, releases energy- Hydrolysis
* Reverse of dehydration synthesis
* Water used to help break bonds
* E.g. Digestion of proteins into amino acids
CHEMICAL REACTIONS continued
EXCHANGE- AB + C AC + B- Involves synthesis & decomposition- Bonds broken & formed- E.g. Glucose + ATP Glucose phosphate +
ADP
INORGANIC COMPOUNDS
Involve ionic bondsDon’t contain carbon (CO & CO2
exceptions)Inorganic compounds common in cells:
- Water- Oxygen (use to release energy from food)- Carbon dioxide (metabolic waste product)- Inorganic salts
INORGANIC COMPOUNDS continued
Water- Most common inorganic- 2/3 of body by weight- 95% of cell- Solvent (dissolved substances)- Lubricant- High heat capacity
INORGANIC COMPOUNDS continued
Salts- Ionic compounds- Dissociate in water- Source of ions electrolytes- Maintain water balance- Involved in blood clotting, muscle & nerve
physiology
INORGANIC COMPOUNDS continued
Acids & Bases- Acid
* Releases hydrogen ions (H+) in solution
* pH < 7.0
* Strong acids completely dissociate in water
- Base
* Releases hydroxide ions (OH-) in solution
* pH > 7.0
pH Scale
- Measures [H+] in solution
- Log scale (ten-fold increase between numbers)
- 0 to 14, 7.0 is Neutral
Buffers- Resist changes in pH- Pick-up or release
H+, keep pH of solution relatively stable
- E.g. carbonic acid (H2CO3) from CO2 + H2O
ORGANIC COMPOUNDS
Involve covalent bondsContain carbonInclude:
- Carbohydrates- Lipids- Proteins- Nucleic acids
ORGANIC COMPOUNDS continued
Carbohydrates- (CH20)n
- Built of monosaccharide(s)- Quickest source of energy (4 cal.gram)- May be stored for energy reserves
CARBOHYDRATES continued
Monosaccharides- Simple sugars- Ribose (5-carbon ring), Glucose (6-carbon ring),
Fructose, GalactoseDisaccharides
- 2 monosaccharides joined by dehydration synthesis (Glucose X 2 = Maltose)
Polysaccharides- Long chain monosaccharides (complex carbs)- Glycogen is a polymer of glucose
ORGANIC COMPOUNDS continued
Lipids- Composed of Fatty Acids + Glycerol (3:1)- Source of maximum energy; long-term
energy storage- Insoluble in water- Make-up most of cell membrane
ORGANIC COMPOUNDS continued
Proteins- Composed of Amino acids joined by peptide
bonds- 23 amino acids vary only in R-group- Chain of amino acids = Polypeptide- Most abundant organic compound- Functions: Structural, Carriers, enzymes,
hormones, Antibodies, Buffers
PROTEINS continued
Complex, 3-D shape determines function- Primary Level = order of amino acids in
polypeptide- Secondary Level = twisting & folding of
chain, held by hydrogen bonds- Tertiary Level = 3 Dimensional shape,
determine function- Quaternary Level = multiple polypeptide
chains
ENZYMES
ProteinCatalyst - Increase rate of reactionRemain unchangedReaction specific; substrates bind at
active siteFunction best at optimal pH &
temperature
ORGANIC COMPOUNDS continued
Nucleic Acids- Composed of Nucleotides
* Phosphate group* Sugar (Ribose or Deoxyribose)* Nitrogenous Base
Adenine & GuanineThymine, Uracil (RNA), & Cytosine
NUCLEIC ACIDS continued
Complementary base pairing Phosphate group & sugar form backboneBases joined by hydrogen bonds & form rungsDNA = Deoxyribonucleic Acid
- Deoxyribose- Thymine (NOT uracil)- Double-stranded- Codes for Proteins
NUCLEIC ACIDS continued
RNA = Ribonucleic Acid- Ribose- Uracil (NOT thymine)- Single-stranded- Involved in Protein Synthesis