What to do about the world s most deadly compound DIHYDROGEN MONOXIDE (DHMO)
Unit 2 Bio-molecules and Biochemistry The Chemistry of Life
It all starts with Water Life depends on water! Why do you think water is so special? Water s formula is H2O, two hydrogens covalently bonded to one oxygen.
Water s Shape Water is a polar molecule Oxygen is slightly negative The Hydrogens are slightly positive Since positive and negative charges attract, this creates a weak bond called a hydrogen bond.
COHESION Due to the hydrogen bonds Water molecules stick to other water molecules. This is called Cohesion. (Co think couple) Surface Tension enables organisms to walk on the water Capillary action works with adhesion to draw water up the roots and stems of plants
ADHESION Due to the hydrogen bonds Water molecules stick to other surfaces. This is called Adhesion (think adhesive, like glue) Works with cohesion to provide capillary action in plants
High Specific Heat Water resists changing temperature 3/4ths of Earth is covered in water which absorbs or releases heat Creates very stable marine and coastal environments Prevents extreme temperature fluctuations like those on other planets
Evaporative Cooling As water evaporates, it removes heat from a surface This is how sweating keeps you cool!
Density of Water Water doesn t follow the normal rule of density. MOST solids sink because they are very dense, but solid water (ice) floats because it is less dense. Becomes more and more dense until 4*C Expands after 4*C and Freezes at the lowest density at 0*C Floating ice prevents lakes and streams from freezing solid.
Density of Water (Gas)
Density of Water (Liquid)
Density of Water (ICE)
Water the Universal Solvent Water will dissolve just about anything which makes it important for chemistry in living things Hydrophilic water loving, substances that dissolve easily in water (i.e. salt) Hydrophobic water fearing, substances that will not dissolve in water, these are non-polar compounds (i.e. oil)
ph Scale Acids and Bases The ph scale is used to determine if a solution is an acid or a base. Acids are found below 7. They get stronger as you approach zero. Neutral substances (like pure water) can be found exactly at 7. Bases are found above 7. They get stronger as you approach 14.
ph levels and Biology Strong acids and strong bases cause damage to cells Living things must maintain a consistent ph level (typically from 6-8) by using buffers, which are substances that can bring a ph level back to normal. Where do you think most of the buffers in your body are found and why? Acid Rain is a major pollutant concern in biology Rain or snow with a ph lower than 5.6 can damage forests and lakes or streams. Caused by smoke mixing with rain water and lowering the ph level.
Effects of Acid Rain
The ph Scale 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Strong Acid Weak Acid Neutral Weak Base Strong Base
Macromolecules Living things are made of Carbon, Hydrogen, Oxygen, Nitrogen, Phosporus, and Sulfur (CHONPS) with a few other elements in small amounts. These create carboyhdrates, lipids, nucleic acids, and proteins, which are taken in from/with food and used to build new cells/tissues Most macromolecules are polymers (large structures) made of monomers (repeating smaller pieces)
Carbohydrates Monomer monosaccharide carbon rings (1 or 2 = sugar; 3 or more = polysaccharide starch) Look for rings of CHO with 1:2:1 ratio (ex- C 6 H 12 O 6 ) Uses energy (food) in all and storage/building in plants Test Benedict s reagent turns orange with sugar; Iodine turns black with starch Draw Them
Examples of Carbohydrates
Lipids (fats) Monomer No monomer/polymer; found as fatty acids chains of C & H Look for Capital E shape OR a C-H chain OR a CHO formula with very few O (ex. C 9 H 18 O 2 ) Uses store energy (fat), waterproof (oil), insulation (blubber) Test Sudan Red stains lipids dark red Draw Them
Lipid Examples
Nucleic Acids (DNA or RNA) Monomer Nucleotides (phosphate, sugar, and nitrogen base); DNA and RNA are polymers Look for P for (phosphorus) OR a spiral helix shape Uses genetic info, instructions for proteins Test No test Draw Them
Nucleic Acid Examples
Proteins Monomer amino acids (20 types); polypeptide chains are the polymers that eventually make the protein Look for the amino head Uses Almost everything from digesting food (enzymes) to coloring your eyes. (structural) (You are one big walking protein) Test Biuret s reagent turns dark purple in the presence of protein Draw Them
Protein Example