Introduction to Biology 2

 Think, pair, & share to complete the “What Makes up an Atom” notes  Complete the “What Makes up an Atom” homework; Read & take notes on Chapter 2 from the book

Is it more dangerous to swim in the ocean or in a lake during a lightning storm?  Substances that release ions in water  The electrically charged (either + or -) ions can conduct an electric current  + ions are cations  - ions are anions  For example, NaCl in H 2 O dissociates into Na + and Cl -

 Water is a polar molecule  Polar = electrons are not shared equally, thus the distribution of charges is uneven  Water has a unique shape due to its polarity and can form hydrogen bonds with other water molecules  The slightly charged ends of the water molecule cause the ions to separate and interact with water instead  Now that’s salty!

 Na+ (sodium) is the major cation found outside of cells & is necessary for the transmission of nerve impulses and muscle movement  Hypernatremia – too much sodium in the bloodstream  Can simply drink more water!  Usually due to dehydration  Hyponatremia – too little sodium in the bloodstream  Normal blood Na+ levels = mmol/L

 Potassium (K+) is the major cation found inside cells & functions in transmission of nerve impulses and muscular function  Hyperkalemia - too much K+  Kidneys may not be working properly to secrete K+  Hypokalemia – too little K+  Kidney disease, poor diet, loss of electrolytes via excessive exercise/sweating  Normal K+ levels = mmol/L

 es/movies/action_pot ential_cartoon.swf es/movies/action_pot ential_cartoon.swf  ducation.com/sites/ /student_v iew0/chapter14/anim ation__the_nerve_im pulse.html ducation.com/sites/ /student_v iew0/chapter14/anim ation__the_nerve_im pulse.html  Let’s summarize this process!

 Strongest Acids: HCl, HNO 3, H 2 SO 4, HBr, HI  Strongest Bases: LiOH, NaOH, KOH, Ca(OH) 2 What do you notice?

 …that release hydrogen ions (H+) in water  HCl releases H+ and Cl- ions  H+ donors

 …that release ions that bond with hydrogen ions called hydroxide ions (OH - )  NaOH is a base that dissociates to Na+ and OH- in water  H+ acceptors

 pH measure the H+ concentration  The concentration of H+ and OH- in body fluids affect chemical reactions and bodily functions!  (too acidic or too basic = very dangerous)  pH of 7 means there is an equal number of H+ and OH- ions (Neutral)  pH < 7 means there is a greater number of H+ (Acidic)  pH > 7 means there is more OH- (Basic)

 Buffers keep the body’s pH in a safe range  Blood pH is normally at 7.4  Buffers combine with H+ ions when they are in excess (too acidic) OR they can donate H+ ions when there are too few (too basic)  If blood pH drops below 7.35, the person has acidosis  If blood pH rises above 7.45, the condition is alkalosis.

 Bicarbonate ion HCO 3 - is a weak base, accepting excess H+ ions  Carbonic acid H 2 CO 3 is a weak acid that will donate extra H+

 Organic = chemicals that include both carbon and hydrogen atoms (C and H)  Macromolecules: lipids, carbohydrates, proteins, nucleic acids  Inorganic = the chemicals that do not include both carbon and hydrogen  Water, carbon dioxide, salts, oxygen, etc.

 Large molecules made up of smaller building blocks or subunits  Define monomer  Define polymer  Make a model of a polymer, showing 3 monomers