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