Acid Precipitation Normal rainfall pH around 5.6 – CO 2 (atmos) + H 2 O → H 2 CO 3 carbonic acid Rain, snow, or fog with a pH lower than pH 5.6 – Caused by sulfur oxides, nitrogen oxides in atmosphere-gaseous compounds which react with water in the air to form strong acids which fall with rain or snow – Source of oxides-burning of fossil fuels (coal,oil, gas) in factories and automobiles – Winds carry pollutants
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Acid Precipitation Normal rainfall pH around 5.6 – CO 2 (atmos) + H 2 O → H 2 CO 3 carbonic acid Rain, snow, or fog with a pH lower than pH 5.6 – Caused.
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Acid Precipitation
Normal rainfall pH around 5.6– CO2 (atmos) + H2O → H2CO3 carbonic acid
Rain, snow, or fog with a pH lower than pH 5.6– Caused by sulfur oxides, nitrogen oxides in
atmosphere-gaseous compounds which react with water in the air to form strong acids which fall with rain or snow
– Source of oxides-burning of fossil fuels (coal,oil, gas) in factories and automobiles– Winds carry pollutants
Acid Precipitation
Damage to lakes, streams Washes away certain minerals from soil (e.g.
Calcium, Magnesium which help buffer soil and are essential nutrients for plant growth
Other minerals (e.g. aluminum) reach toxic concentrations when acidification increases solubility
Acid Precipitation Upside
Pollution control programs here, Canada, some European countries– Decrease in oxide emissions over several decades– Acid rain has decreased, but recovery is slow
Chemistry of LifeChemistry of Life
Part deuxPart deux
Chemistry of Life Outline
I. Introduction
II. Macromolecules-Large Organic Molecules
A. Carbohydrates
B. Lipids
1. glycerides
2. phospholipids
C. Proteins
D. Nucleic Acids
Inorganic vs. Organic
Inorganic compounds
Organic compounds:
Recall Carbon 6C– 4 electrons in outer shell– Can form up to 4 covalent bonds with other atoms– Recall bonds can be single, double, triple– Often bond with carbon atoms to create chains of carbons
Carbon Chemistry
Hydrocarbons:
Examples: methane-simplest hydrocarbon CH4 Hydrocarbons undergo reactions that release
relatively large amounts of energy Replace a H with a C and the backbone grows,
keep going and you get long chains, branched chains, and ring structures
No polarity to bonds, not soluble in water
Isomers
Functional Groups
Groups of atoms attached to the carbon backbone
Most chemical reactions that occur within organisms involve transferring a functional group from one molecule to another or breaking a carbon-carbon bond
Behave consistently from one organic molecule to the next
Macromolecules
Large organic molecules
3 of these are– Long molecules made up of similar or identical
building blocks linked by covalent bonds– Repeating units are called
Assembly and Disassembly
Chemical mechanism by which cells make and break polymers is the same even though monomers may be different for different macromolecules
Enzymes: special class of proteins which catalyze (speed up) reactions between specific substances
Assembly and Disassembly
Condensation: monomer connection by reaction in which 2 molecules are covalently bonded to each other through loss of H2O (dehydration)
Assembly and Disassembly
Hydrolysis: “water breaking”-polymers broken down into monomers. H from water attaches to one monomer, OH attaches to adjacent monomer
Carbohydrates
Structure– Monosaccharide-– Disaccharide-– Polysaccharide-– C, H, O in 1:2:1 ratio– Examples
Function
Important Carbohydrates
Glucose: C6H12O6 forms ring structure in solution, major nutrient for cells, carbon skeletons serve as raw material for synthesis of other types of small organic molecules– Water soluble– Often linked to form disaccharide for transport
Polysaccharides
Glycogen: storage form of glucose in animals, long chains, highly branched therefore more insoluble in solution. Easily broken down via enzyme catalyzed hydrolysis to glucose
Starch: storage form of glucose in plants
Polysaccharides
Cellulose: also made of glucose monomers but structurally different than starch. Component of tough walls that encase plant cells, not readily broken down
Chitin: structural also, used by crustaceans, insects, spiders to build their exoskeletons–
Lipids
Insoluble in water (polar) but soluble in oil (non-polar)
Types of Lipids:
Many C-H bonds Functions include
Lipids
Built from 2 subunits– Glycerol: 3-C alcohol with 3 OH groups which forms the
backbone of the lipid molecule– Fatty acids: long chains of C-H (often 16-18 carbons long-
hence the insolubility) Saturated: single bonds between carbons, chains lay flat,
decreased reactivity. Solid at room T (lard, butter) Most animal fats
Unsaturated: one or more double bonds which cause “kinks” in chains, therefore increasing reactivity. Liquid at room T (olive oil, cod liver oil) Most plant and fish fats
– 1-3 fatty acid chains per glycerol molecule
Great energy storage
Phospholipids
Glycerol backbone with 2 fatty acid tails. Phosphate group PO4
- attached
Form lipid bilayer at cell surface
Steroids
Carbon skeleton of 4 rings Vary in functional groups attached and
therefore vary in function Cholesterol:
Proteins
Account for almost 50% of dry weight of cells Instrumental for many cell functions including:
– Structural support and movement(bone,cartilage)– Storage/transport molecules (hemoglobin)– Hormones (insulin-sugar breakdown)– Enzymes (control of cellular reactions
Protein Chemistry
R groups differ for each AA
Amino acids joined together by special covalent bonds called peptide bonds
Protein Structure
Primary structure: specific and unique AA sequence
Secondary structure: parts of AA chain bonded together via hydrogen bonds into helical structure (alpha helix) or sheet structure
Tertiary structure: due to interactions of R groups-sheets often form fibers that have structural function, helical structures tend to have globular form-heavily influenced by R group
Protein Structure
Quaternary structure: Proteins that consist of more than one polypeptide chain.– Ex: Hemoglobin (carries O2 in body) globular protein
with 4 chains, collagen fibrous protein of 3 chains forming a triple helix-suits function of connective tissue in skin, bone, tendons etc.
Denaturation: change in 3D structure when chemical environment of protein changed– Exs. pH, salt concentration, temperature etc.
Nucleic Acids
Nucleotide monomer– 5 C sugar-either ribose or deoxyribose– N-containing base
Single ring Pyrimidine: C, T, U Double ring purine A, G
– Phosphate group
Deoxyribonucleic Acid (DNA)
Nucleotide has deoxyribose as 5C sugar Double helix structure (double strand of
nucleotides) Lives in nucleus of cells
Ribonucleic Acid (RNA)
Nucleotide has ribose as 5C sugar Single chain nucleotide structure (single
stranded) Directs production of proteins
– Once synthesized (via DNA), moves out of nucleus to protein synthesis machinery in cell and base sequence directs which AA’s are joined together