CHAPTER 2

: CHEMIC

AL

BASIS O

F LIF

E

2.2 STRUCTURE OF MATTER

All matter is made up of atoms – the smallest building blocks of matter

Atoms make up elements – pure chemical substance w/ only 1 type of atom

There are 118 elements on the current periodic table

92 of these are naturally occurring

Living organisms require about 20 elements

Oxygen, Carbon, Hydrogen, & Nitrogen make up more than 95% of the human body (table 2.1)

ATOMIC STRUCTURE

2.3: CHEMICAL CONSTITUENTS OF CELLS

Organic – can dissolve in water but more likely to dissolve in organic liquids (Ether or alcohol)

ones that do dissolve in H2O do not release ions nonelectrolytes

contain both carbon and hydrogen

Inorganic – generally dissolve in water or react with water to release ions electrolytes

INORGANIC SUBSTANCES

Water

- Most abundant compound in living material

- Accounts for 2/3 of the weight of an adult human

- Major component of blood and other body fluids, including those within cells

Oxygen

- Enters the body through the respiratory organs

- Transported throughout the body by blood and red blood cells

INORGANIC SUBSTANCES

Carbon Dioxide

- Simple carbon-containing compound, waste product when certain metabolic processes release energy

- Exhaled from the lungs

Salts

- Abundant in tissues and fluids

- Provide many necessary ions needed for metabolic processes like transport substances into and out of cells, muscle contraction, & nerve impulse conduction

ORGANIC SUBSTANCESCarbohydrates

- Provide much of the energy that cells require

- Supply materials to build certain cell structures

- Often stored as reserve energy supplies

- Molecules contain atoms of carbon, hydrogen, & oxygen

- Usually have twice as many hydrogen atoms as oxygen atoms

- Carbon atoms of carbohydrate molecules join in chains whose lengths vary with the type of carbohydrate

CARBOHYDRATES

Monosaccharides (simple sugars)

- Have six carbon atoms (hexoses)

- Building blocks of more complex carbohydrate molecules

- Ex. Glucose, fructose, galactose

CARBOHYDRATES

Disaccharides (double sugars)

- Molecules each contain two simple-sugar building blocks

- Ex. Sucrose (table sugar) & lactose (milk sugar)

Polysaccharides

- Made up of many simple-sugar units joined together

- Ex. Plant starch & glycogen humans synthesize this polysaccharide (similar to starch)

LIPIDS

Insoluble in water but soluble in certain organic solvents (ether & chloroform)

Include fats, phospholipids & steroids

Fats – used to store energy for cellular activities; can store more than carbohydrates

- Fatty acids and glycerol are the building blocks of fats

- Each one contains carbon, hydrogen & oxygen atoms

- Each fat contains a glycerol molecule and three fatty acid molecules

- The glycerol portion of every fat is the same, but many different combination of fatty acids

- Fatty acids with with single carbon-carbon bonds are called saturated fats

- Ones with double bonds between carbon atoms are unsaturated fats

LIPIDS

Phospholipid

- Similar to a fat molecule in that it has a glycerol molecule and fatty acid chains

- Only has 2 fatty acid chains instead of 3

- Third portion is a phosphate group that is soluble in water

Steroid

- Include four connected rings of carbon atoms

- Ex. Cholesterol, estrogen, progesterone, testosterone, & several hormones from the adrenal glands

PROTEINS

- Serve as structural materials, energy sources, and hormones

- Combine with carbohydrates to function on cell surfaces as receptors - Specialized to bond to particular kinds of molecules

- Antibodies act against foreign substances that enter the body

- Enzymes – catalyze vital metabolic processes- Speed specific chemical reactions without being consumed by the reactions

NUCLEIC ACIDS

Form genes

Take part in protein synthesis

Generally very large & complex molecules

Contain atoms of carbon, hydrogen, oxygen, nitrogen, & phosphorus

These are bound into building blocks called nucleotides

NUCLEIC ACIDS

2 major types:

RNA (ribonucleic acid) – composed of molecules containing ribose

DNA (deoxyribonucleic acid) – contains deoxyribose

DNA stores information in the form of a genetic code

cells use this info to make protein molecules

RNA molecules aid in protein synthesis