CHAPTER 2

A. Dictionary definitions are circularB. Life is defined as a series of

characteristics organisms share1. Use Energy2. Grow3. Develop4. Reproduce5. Cells6. Homeostasis7. Maintenance & Repair8. Heredity9. Sensitivity10. Death

A. ATOMS1. Smallest building blocks of matter2. Atomic structure

Living things are made of the same things as the rest of the universe• Organisms are chemical machines• Knowledge of chemistry is important in understanding life processes

Protons Positive charge p+

Determine chemical behavior Give ATOMIC NUMBER

Neutrons No charge n0

n + p = ATOMIC MASS

Give the isotope

Electrons Negative charge e-

Same number as protons making atoms neutral

Orbit nucleus in energy levels (2n2)

Higher the level the greater the energy

Carry energy through living systems

1

H1.0079

1

H1.0079

ATOMIC NUMBER

ATOMIC MASS

SYMBOL

HYDROGEN

ATOMIC NUMBER?

ATOMIC MASS?

NAME?

3

7

Lithium

p+e-

n0

a. Only 92 are naturally occurring Others only exist in the laboratory The way these naturally occurring

elements combine makes up everythingb. Only 20 of the 92 are common in living

thingsc. Only 4 of those 20 make up 97% of all living

matter

All others are considered TRACE ELEMENTS

C. CHEMICAL BONDS1. Force holding atoms together2. Atoms bond to fill outer shells

a. By gaining, losing, or sharing electronsb. Makes atoms stable

3. Types of bonds

11

Na22.9897

11

Na22.9897

1st Energy Level

2e-

1st Energy Level

2e-

2nd

Energy Level

8e-

2nd

Energy Level

8e-

3rd Energy Level

1e-

3rd Energy Level

1e-

17

Cl35.453

17

Cl35.453

1st Energy Level

2e-

1st Energy Level

2e-

2nd

Energy Level

8e-

2nd

Energy Level

8e-

3rd Energy Level

7e-

3rd Energy Level

7e-

Ions are charged particles (+ or -)• Occur when atoms gain or lose electrons• IONIC BONDS result from the attraction of

oppositely charged ions

Loses e- Loses e-

Gains e- Gains e-

+ -

Ionic Bond

Na+ Cl-

NaCl

Form MOLECULES• Occur when atoms share electrons to fill outer shells• Electrons are always in shared pairs• Follow the OCTET RULE

HydrogenHydrogen H2H2+ Hydrogen+ Hydrogen

Formed by COVALENT BONDING

Needs1

electron

Needs 2 electrons

ATOM

Shares

HHYDROGEN

OOXYGEN

Valence Electrons are in the outer energy level

NNITROGEN

CCARBON

1 2 3 4

B. COMPOUNDS1. Composed of two or more elements2. Elements are chemically combined

Lack CARBON Exceptions are:

Many in living things

CO2

CARBON DIOXIDE

CaCO3

CALCIUM CARBONATE

INORGANIC WATER Most essential nutrient Makes up 2/3 body weight Major component of blood Lubricates joints Biochemical Reactions Lost constantly

• sweat• elimination of waste• exhaling

In all living things Contain CARBON Can be gases like

These gases are referred to as HYDROCARBONS

CH4

METHANE

ORGANIC MACROMOLECULES Formed by Organic Compounds in living things Large complex molecules Long chains or rings of carbon atoms

Inorganic Molecules are much smaller

1. PROTEINS2. CARBOHYDRATE

S3. LIPIDS4. NUCLEIC ACIDS

4

3

2 1

A.CARBOHYDRATES1. Body’s primary

source of energy2. Supplied by plants3. Plants make food

by the process of PHOTOSYNTHESIS

CARBON DIOXIDECARBON DIOXIDE

WATERWATER CARBOHYDRATESimple Sugar

CARBOHYDRATESimple Sugar

OXYGENOXYGEN

Solar

Energy6CO2 6H2O C6H12O6 6O2++

a. MONOSACCHARIDES Single sugar units Examples:

GLUCOSE Main source of energy for cells Blood Sugar

FRUCTOSE Sweetest Honey, Fruit

GALACTOSE Part of milk sugar

GLUCOSE

C6H12O6

b. DISACCHARIDES Double sugar units Examples:

SUCROSE Table Sugar (cane sugar) glucose + fructose

MALTOSE Brewing glucose + glucose

LACTOSE Milk sugar glucose + galactose

Suffix OSE refers to sugars

a. POLYSACCHARIDES Many sugar units Long complex chains of sugars

b. Examples:

STARCH Store energy in plants 100’s of glucose subunits in a line

GLYCOGEN Animal starch Stored in muscles and liver 100’s of branched glucose subunits

B. LIPIDS1. Fats and Oils2. Store Energy in

living thingsa. Large number of

C to H bondsb. Store 2x the

energy per gram than carbohydrate

3. Triglycerides are the most common dietary fat

4. Types of Fats

a. SATURATED FATS

C – C are single Hold maximum

number of H atoms Usually solid at

room temperature Butter, fat on meat,

lard, etc.

SATURATED FATS High levels in

diet may lead to:

OBESITY

CARDIOVASCULAR DISEASE

CANCER

b. UNSATURATED FATS

One or more C – C bonds are double

Not saturated with H atoms

Usually liquid at room temperature

Olives, olive oil, peanuts, peanut oil, cooking oils, etc.

Food taste Fat soluble vitamins Calories (ENERGY) Prevents deficiencies in women and children Insulation

5. Other Lipidsa. Steroids

Sex Hormones Cholesterol Chlorophyll

b. Waxes Earwax Beeswax

C. PROTEINS1. Major part structural part of living things

COLLAGENSkin, Bone, Cartilage, Tendons

KERATINHair, Horns, Feathers

2. Act as enzymes3. Composed of long chains of amino

acids

NH2 COOH

R is the variable side (determines the acid)R = H then Glycine R = CH3 then Alanine

a. Twenty kinds of amino acids found in proteins (most end in “ine”)

Essential Amino Acids (8)Only in food

Nonessential Amino AcidsCan be produced by body using essential amino acids

b. A typical protein is at least 100 amino acids linked together called a polypeptide

Specific acids and sequence determine physical properties and function

20100 possible combinations for such a protein

a. PRIMARY • Order of acids

b. SECONDARY• Interactions

cause them to bend or twist

• Called a HELIX• Form fibrous

proteins like hair and nails

c. TERTIARY • Most fold into a

compact mass• Typical of

enzymes

d. QUATERNARY• Mix of two or

more protein chains

• Characteristic of hemoglobin and insulin

1. DNA Deoxyribonucleic Acid Forms a DOUBLE

HELIX Makes up

Chromosomes

2. RNA Ribonucleic Acid Directs formation of

proteins

D. NUCLEIC ACIDS

THE END