Biology 3 Ch 2 Chemistry of Life

1

Biology 3

Ch 2 Chemistry of Life

Dr. Terence Lee

LA Harbor College

Atoms

• There are 2 main parts to an atom:1. Electrons

i. Negatively charged

ii. Surrounds nucleus

iii. Almost no mass

2. Nucleus

Atomic Nucleus

1. Protons

i. Positively charged

ii. Same mass as neutrons

iii. Number of protons determines

the type of atom

2. Neutrons

2

Examples of Elements

important to Life

• H – Hydrogen

• C – Carbon

• O – Oxygen

• N – Nitrogen

• P - Phosphorus

What makes one element different from the next?

Molecule

H2O2

H2O

Chemical Reactions

1. Change in matter when in which different chemical

substances are created by forming or breaking

chemical bonds.

3

Covalent Bonds

1. Are bonds formed when

two atoms share a pair of

electrons.

Ionic Bonds

1. Ionic bonds occur when a positive ion bonds with a negative ion.

4

Hydrogen Bonds

Hydrogen Bonds

5

Water

• Essential to Life

• Has very unique properties

Water Fact

Water Facts

• Large bodies of water help insulate the surrounding land to prevent large fluctuations in temperature.

• .

6

pH Scale

� The amount of H+ in a solution is a measure of its acidity and is called pH.

Acids, Bases, and Salts

1. Acids – ionic compounds that release

hydrogen (H+ )

2. Bases – ionic compounds that remove H+

from solution, usually have –OH- groups.

3. Salts –

Chemistry Part 2: Organic

Molecules1. Carbohydrates

2. Proteins

3. Nucleic Acids

4. Lipids

7

Organic Molecules

Organic Chemistry - the chemistry of:

1. compounds containing carbon

Carbon

1. Four electrons on outer shell

2. Bonds are usually covalent

Methane (CH4)

Carbon

Double bonds

Hydrocarbon chain and a ring compound.

CO2

CH3COH

CH2CH2

CH2CHOH

shorthand

8

Carbohydrates

1. Composed of carbon, hydrogen, and oxygen.

2. Forms monomers called simple sugars or

monosaccharides

3. Are found in:

2.10 Complex carbohydrates are time-released packets of energy.

�More than 1 sugar (monosaccharide) unit

�Disaccharides• sucrose

• lactose

� Polysaccharides• starch

• cellulose

Polysaccharide

• Three main types

9

Complex Sugars

Animals can’t digest cellulose

Cow

Termite

Lipids

10

Lipids

• Saturated fatty acid =

11

Lipids

• Saturated fatty acid –

– Takes up less space

– Solid at room temperature

• Unsaturated –

Lipids

Lipids

Margarine

12

• Resemble neutral fats but contain a charged phosphate

group (PO4).

Phospholipids

Lipids

Steroids

• Characterized by their inter locking rings of carbon

• Types of steroids:

13

Proteins

A chain of amino acids makes a

protein

Nucleic Acids

• DNA = deoxyribonucleic acid

• RNA = ribonucleic acid

• Are all composed of

Nucleotides

• Nucleotide:

14

Nucleic Acids

• Binding rules for the

bases:

Nucleic Acids

• DNA

– Deoxyribonucleic acid

– Double stranded

– Contains bases A, T, G, and C

– Found in nucleus and mitochondria of cell

• RNA

Nucleic Acids

• Nucleic Acids -> DNA -> Chromosome