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
Na + and Cl -
O dissociates into


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 = 135-145 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 = 3.5 - 5.0 mmol/L



 http://brainu.org/fil es/movies/action_pot ential_cartoon.swf
http://highered.mhe
ducation.com/sites/0
072495855/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 donate extra H+
CO
3 is a weak acid that will


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