Chapter 3 – The Chemical Basis of Life II: Organic Molecules

Organic Molecules

Molecules that contain carbon

Carbohydrates

sugars, starch, fibers that your body uses for energy

• composed of carbon, hydrogen, and oxygen

Monosaccharides

Simple sugars that are the basic building blocks of carbs

• the monomers used to construct larger carbohydrates

• glucose & fructose

Isomers

Molecules with identical chemical formulas but different structures (ex: galactose, glucose, and fructose)

Disaccharides

two monosaccharides joined together

• example: lactose, maltose, and sucrose; formed from glucose + sucrose

Glycosidic bond

The covalent bond formed between 2 sugars

Polysaccharides

complex; formed when many monosaccharides are linked together

• example: starch, glycogen, cellulose

Lipids

Composed predominantly of hydrogen and carbon atoms and are nonpolar and therefore very insoluble in water

Triglycerides (type of lipid)

Molecules commonly known as fats and oils, formed by bonding a glycerol to 3 fatty acids

Fatty acids (lipid)

Long hydrocarbon chains with a carboxyl group at one end. They are joined by dehydration and broken apart by hydrolysis (found in triglycerides)

Saturated fatty acids

Do not have any double-bonded carbons (C=C) within the hydrocarbon chain; all carbons are connected by single bonds (C-C) and the molecule has a straight structure

• straight and solid at room temp

Monounsaturated fatty acids

Contain one C=C, which introduces a kink into the shape

Polyunsaturated fatty acids

Contain two or more C=C

Phospholipids

Similar in structure to triglycerides but are formed from glycerol, 2 fatty acids, and a phosphate group

• amphipathic molecules: polar hydrophilic phosphate “head” and a nonpolar hydrophobic fatty acid “tail”)

Steroids

Have four interconnected rings of carbon atoms

• primarily composed of carbon and hydrogen

• usually insoluble in water

Waxes

Long structures that resemble a fatty acid attached to another long hydrocarbon chain and are very nonpolar, excluding water

Proteins

large molecules essential for the structure, function, and regulation of the body

• Composed of carbon, hydrogen, oxygen, nitrogen

Amino acids

building blocks of proteins

• Joined together through a dehydration reaction, connecting the carboxyl group of one to the amino group of another

Peptide bond

The covalent bond formed between the carbon and nitrogen

Polypeptides

Polymers of amino acids

N-terminus

The end with a free amino group

Phospholipid bilayer

fundamental for forming cell membranes

Nucleic Acids

responsible for the storage, expression, and transmission of genetic information (two classes: DNA and RNA)

Nucleotides are composed of

a phosphate group, a pentose sugar (ribose or deoxyribose), and a nitrogenous base (purines: A & G, pyrimidines: C, T & U).