BIOCHEMISTRYThe Chemical

Composition of Living Things

PHYSICAL & CHEMICAL PROPERTIES & CHANGES

Physical Properties Describe physical

appearance Color, texture,

shape Physical Changes

Change in appearance only

Reversible Melting, freezing,

breaking, etc.

Chemical Properties Describe how

material reacts Flammability,

reactive, & pH Chemical Changes

Change in composition

Irreversible Burning, oxidizing,

digesting, etc.

CHEMICAL RXNS W/IN LIVING ORGANISMS

Chemical rxns require energy (activation energy)

Enzymes lower the activation energy needed to start a chemical rxn. Catalyst = speed

things up Allows biological

processes to happen faster

ENZYMES: HOW THEY WORK

Shape determines function Specific enzyme

for each different chemical rxn

Ex: Lactase enzyme speeds up the metabolism of lactose

Denature If an enzyme’s

shape changes, it won’t work as effectively

Caused by: Change in temp Toxins (acids, bases) Radiation

ATOMIC STRUCTURE

# protons =

+ charge

# neutrons =

No charge

# electrons =

- charge

Atomic Number

Atomic Mass

Symbol

C

6

12.01

ATOMIC DIAGRAMS Nucleus –

protons + neutrons

Electron clouds Surround nucleus 1st – 2nd – 3rd – 4th – 5th – 6th – 7th -

ATOMIC DIAGRAMS

Valence Electrons – Electrons in the

outer most energy level

Octet Rule Must fill 1st level

before move onto the next

CARBON

Protons -

___________

Neutrons -

_________

Electrons -

_________

Valence - __________

SODIUM

Protons -

___________

Neutrons -

_________

Electrons -

_________

Valence - __________

BORON

Protons -

___________

Neutrons -

_________

Electrons -

_________

Valence - __________

CHLORINE

Protons -

___________

Neutrons -

_________

Electrons -

_________

Valence - __________

PERIODIC TRENDS

BONDING

2/more atoms join to become more stable Atoms become stable when they have a

full outer energy level Most organic elements need 8 electrons Hydrogen is the exception – it only needs 2

IONIC BONDS

Atoms gain/lose electrons to increase stability Gains (-) ion Loses (+) ion

Opposing charges attract forming a bond

IONIC BONDS

Formulas 1st – (+) ion 2nd - (-) ion # indicates how

many of each element are needed

NaCl

Sodium & Oxygen

COVALENT BONDS

2/more atoms share electrons to increase their stability

Occurs when neither element can “give away” electrons

Atoms joined by covalent bonds are called molecules

COVALENT BONDS

Carbon & Sulfur

BONDING

Nitrogen & Oxygen

Bond ____________ Formula ___________

Unique Characteristics of Water

Most dense in liquid form Allows ice to float Importance to living things?

Aquatics Terrestrial

Unique Characteristics of Water

Water has a high surface tension Cohesion – molecules “stick” to themselves Adhesion – molecules “stick” to another

substance Capillary Action – molecules drawn up a tube Importance to living things?

Blood Plants

Unique Characteristics of Water

High Specific Heat Resists changes in temperature Requires increased energy to raise temp Importance for Living Things?

Aquatic Organisms Mammals Climate

Unique Characteristics of Water

Versatile Solvent Water is “polar” or charged Any polar substance will dissolve in water “Like dissolves Like” Gives water the ability to form mixtures, acids

& bases Importance to living things?

Structure Nutrient/waste exchange Buffer

Unique Characteristics of Water

pH Scale

Water forming Mixtures

Solutions: Homogeneous 1

substance equally dissolved in another

Examples:

Suspensions: Heterogeneous

2/more layers form; particles “hanging”

Examples:

Water forming Mixtures

COLLOID Gel-like substance

w/clusters large molecules spread throughout

Properties both liquid & solid depending upon pressure applied

Examples: