AP BIO: Unit 1 Biochemistry

proton

subatomic particles that carry a positive charge; the number determines the identity of the element and defines the atomic number of the element

neutron

particles carry no charge (are neutral); number of it can change

isotopes

atoms of the same element with different numbers of neutrons

electrons

carry a negative charge; located in the “electron cloud;” attracted to the positive protons in the nucleus but can move in the electron cloud

Ions

atoms with different number of electrons than the normal amount for that element

E-levels or e-shells

where the electrons are located within an atom or molecule

molecule

two or more atoms that are covalently bonded together

valence shell

where the outer most electrons are located on an atom

valence e-

refers to the outer most electrons; most important for chemical bonds and the chemical properties of an element or molecule

octet

atoms react with other elements in order to obtain a full _____ (8 valence e- and chemically stable)

covalent bond

(intramolecular bond); sharing of valence electrons between atoms

polar molecule

carry a slight electrical charge at opposite poles

nonpolar molecules

do not have an electrical charge

electronegativity

refers to an atom’s desire to acquire electrons

Hydrogen

least electronegative atom

TIP

Molecules which contain oxygen and nitrogen are likely to be polar

ionic bonds

form between metal + non metal atoms; metal atoms loses an election and non-metal atom gains an electrons; strong when dry, weak when wet

salts

compounds held together by ionic bonds

cations

ions which possess a positive charge because they have more protons than electrons a

anions

ions which possess a negative charge because they have more electrons than protons

Hydrogen bonds

fairly weak compared to covalent and ionic bonds; intermolecular attractions that occur between polar molecules;

Van Der Waals Interactions (London Dispersion Forces)

temporary intermolecular attractions

Carbohydrates

molecules with a 1:2:1 ratio carbon, hydrogen, oxygen

good energy storage molecules (sugars, starch, glucose)

Monosaccharides

simplest carbohydrate; 6 carbons sugars (glucose)

fructose

a structural isomer of glucose

galactose

a stereoisomer of glucose

enzymes

act on different sugars can distinguisher structural and stereoisomers of this basic six-carbon skeleton 

hexoses

structural isomers, same chemical formula but a different arrangement of atoms