Chemistry You gotta’ know it to understand LIFE!

ChemistryYou gotta’ know it to understand

LIFE!

Atomic Structure

Elements

Table 2-1

Isotopes

• Some applications of radioactive isotopes in biological research are:– Dating fossils– Tracing atoms through metabolic processes– Diagnosing medical disorders

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Positron Emission Tomography• http://www.sumanasinc.com/webcontent/animations/content/positronemissiontomography.html

Ions

• Normal Atoms

Ions

Electron Energy Levels

Electron Energy Levels

• Why “Octet”

Ionic Bonding

Covalent Bonding

Molecules

Hydrogen

Molecules

Amino Acids InsulinLipid

DNA

Enzyme Molecule

Chemical Reactions

Synthesis vs. Decomposition

Two important Biological Reactions

1. SYNTHESIS

eg.

2. DECOMPOSITION

eg.

WATER

Hydrogen Bonding- Hydrogen will often have a positive (+) charge when bonded to another element in a molecule. This positive charge can interact with other charges on elements of other molecules or even within the same molecule

H Bonding affects boiling and freezing points of compounds as well as the shapes of many biological molecules.

WATER

Water is a polar compound

Four emergent properties of Four emergent properties of water contribute to Earthwater contribute to Earth’’s s fitness for lifefitness for life

• Four of waterFour of water’’s properties that facilitate s properties that facilitate an environment for life are:an environment for life are:

– Cohesive behavior (capilary action)Cohesive behavior (capilary action)– High Specific Heat (Ability to moderate High Specific Heat (Ability to moderate

temperature)temperature)– Expansion upon freezing (Lowers its Expansion upon freezing (Lowers its

Density)Density)– Solvent propertiesSolvent properties

ALL OF THESE ARE THE RESULT OF ALL OF THESE ARE THE RESULT OF WATER’S POLAR PROPERTYWATER’S POLAR PROPERTYCopyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 3-UN4

Liquid water:transient hydrogenbonds

Ice: stable hydro-gen bonds

Water’s Cohesive Property

The specific heat is the amount of heat required to raise the temperature by one degree Celsius.

Specific Heat Capacity of water is Higher than most substances

and is the result of water’s polar property.

CAUTION! FILLING IS HOT?

Specific heat capacity of water is larger than soil, so the rise of temperature is less for

water, all other things being equal.

This is why it’s typically cooler near the coast in summer and warmer in the winter.

Fig. 3-5

San Diego 72°

40 miles

Pacific Ocean

70s (°F)

80s

90s

100s

Santa Barbara 73°

Los Angeles (Airport) 75°

Burbank90°

San Bernardino100°

Riverside 96°Santa Ana 84° Palm Springs

106°

Adhesion• Adhesion is the property of water that

allows it to cling to other substances. Water’s polar characteristics cause it to be attracted to other polar substances OR it can induce a

charge on the substance to which it clings.

This adhesion causes a phenomenon known as Capillary Action

Water Transport in Plants

This transport is a property of water’s POLARITY that give it both

cohesiveness and adhesiveness

Acids and Bases

Threats to Water Quality on Earth

• Acid precipitation refers to rain, snow, or fog with a pH lower than 5.6

• Acid precipitation is caused mainly by the mixing of different pollutants with water in the air and can fall at some distance from the source of pollutants

• Acid precipitation can damage life in lakes and streams

• Effects of acid precipitation on soil chemistry are contributing to the decline of some forests

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

• Human activities such as burning fossil fuels threaten water quality

• CO2 is released by fossil fuel combustion and contributes to:– A warming of earth called the “greenhouse”

effect– Acidification of the oceans; this leads to a

decrease in the ability of corals to form calcified reefs

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 3-11

EXPERIMENT

RESULTS

Cal

cif

icat

ion

rat

e(m

mo

l C

aCO

3

per

m2 p

er d

ay)

[CO32–] (µmol/kg)

150 200 250 3000

20

40

• http://www.youtube.com/watch?v=fJbyC-eqrfs

You should now be able to:

1. List and explain the four properties of water that emerge as a result of its ability to form hydrogen bonds

2. Distinguish between the following sets of terms: hydrophobic and hydrophilic substances; a solute, a solvent, and a solution

3. Define acid, base, and pH4. Explain how buffers work

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings