Chapter 2

The Chemical Basis of Life

Water

Most important molecule for life

Stabilizes body temperature

Provides protection

Facilitates chemical reactions

Transportation

Water Molecule

Polar molecule

Electrons aren’t shared equally

Creates partial charges within the molecule

Covalent Bond

Formed by atoms sharing electrons

Shared electrons circle both nuclei

Compounds held together by

covalent bonds are called molecules

Hydrogen Bonding

Attraction between polar molecules

Due to the attraction of the partial charges within

the molecules

Water is able to form a lot of hydrogen bonds

Hydrogen bonds allow water to do a lot of things

Dehydration and Hydrolysis

Chemical reaction involving water

Dehydration forms polymers by removing

a molecule of water

Also called condensation reaction

Dehydration and Hydrolysis

Hydrolysis breaks polymers by adding a

molecule of water

Acids, Bases, and pH

pH measures how acidic

or basic a substance is

Acids release H+ into

water

Bases release OH- into

water

Pure water is neutral

pH scale goes from 0-14

7.0 is neutral

Acids have pH below 7

Bases have pH above 7

Each number is 10X different on the pH scale

Buffers

Resist changes in pH

Help maintain

homeostasis

If pH isn’t constant, a

chemical reaction may

not occur correctly

Questions?