Unit 1: Chemistry of life - Water, biological macromolecules

acid

molecule that donates hydrogen ions and increases the concentration of hydrogen ions in a solution

adhesion

attraction between water molecules and other molecules

anion

negative ion formed by an atom gaining one or more electrons

atom

smallest unit of matter retaining all chemical properties of an element

atomic number

total number of protons in an atom

atomic weight

calculated mean of the atomic weights of an element’s isotopes

balanced chemical equation

reaction statement with equal numbers of each atom in reactants and products

base

molecule that donates hydroxide ions or binds excess hydrogen ions to decrease hydrogen ion concentration

buffer

substance resisting pH change by absorbing or releasing hydrogen or hydroxide ions

calorie

heat required to change temperature of one gram of water by one degree Celsius

capillary action

water drawn toward charged surfaces in narrow tubes

cation

positive ion formed by an atom losing electrons

chemical bond

interaction between atoms forming molecules

chemical reaction

process rearranging atoms in molecules

chemical reactivity

ability to combine and form chemical bonds

cohesion

intermolecular force between water molecules from polarity; causes surface tension

compound

substance made of molecules with atoms of at least two different elements

covalent bond

strong bond formed by shared electrons

dissociation

release of an ion from a molecule

electrolyte

ion needed for nerve conduction, muscle contraction, and water balance

electron

negatively charged subatomic particle in orbitals

electron configuration

arrangement of electrons in shells

electron transfer

movement of electrons between elements, forming ionic bonds

electronegativity

ability to attract electrons

element

substance that cannot be broken down; defined by proton number

evaporation

separation of surface molecules from water or organisms

functional group

atom group imparting specific function to carbon skeleton

heat of vaporization of water

energy required to convert liquid water to vapor

hydrogen bond

weak bond between slight positive hydrogen and slight negative atoms

hydrophilic

ions or polar molecules that interact well with water

hydrophobic

nonpolar molecules that avoid water

inert gas

element with filled outer shell; unreactive

ion

atom/group with unequal protons and electrons

ionic bond

bond between oppositely charged ions

irreversible chemical reaction

reaction proceeding in one direction only

isotope

form of an element with different neutron numbers

mass number

total protons and neutrons

molecule

two or more bonded atoms

neutron

uncharged particle in nucleus, mass of one amu

noble gas

inert gas with full outer shell

nonpolar covalent bond

equal sharing of electrons

nucleus

core of atom containing protons and neutrons

octet rule

atoms most stable with eight electrons in outer shell

orbital

region around nucleus containing electrons

organic molecule

carbon-containing molecule (except CO₂)

pH scale

scale 0–14 inversely proportional to hydrogen ion concentration

polar covalent bond

unequal electron sharing creating partial charges

product

molecule on right side of chemical equation

proton

positively charged nuclear particle

reactant

molecule on left side of chemical equation

reversible chemical reaction

reaction proceeding in both directions

solvent

substance dissolving another

specific heat capacity

heat needed to change temperature of one gram by one degree Celsius

sphere of hydration

water molecules surrounding charged/polar molecules

surface tension

resistance to separation at liquid surface from cohesion

valence shell

outermost electron shell

van der Waals interaction

weak attraction from temporary charges

alpha-helix structure (α-helix)

type of protein secondary structure formed by helical folding stabilized by hydrogen bonds

amino acid

protein monomer with central carbon bonded to amino group, carboxyl group, hydrogen, and variable R group

beta-pleated sheet (β-pleated)

protein secondary structure with pleats formed by hydrogen bonding along the backbone

biological macromolecule

large essential molecule built from smaller organic units

carbohydrate

macromolecule with C

cellulose

plant cell wall polysaccharide providing structural support

chaperone

protein aiding proper folding of nascent proteins

chitin

carbohydrate forming arthropod exoskeleton and fungal cell walls

dehydration synthesis

reaction linking monomers and releasing water

denaturation

loss of protein shape from heat, pH change, or chemicals

deoxyribonucleic acid (DNA)

double-helical hereditary molecule

disaccharide

two sugar monomers linked by glycosidic bond

enzyme

protein catalyst for biochemical reactions

glycogen

carbohydrate storage form in animals

glycosidic bond

bond between monosaccharides formed by dehydration reaction

hormone

signaling molecule regulating physiological processes

hydrolysis

breakdown of larger molecules using water

lipid

nonpolar, water-insoluble macromolecule

messenger RNA (mRNA)

RNA carrying genetic information to ribosomes

monomer

smallest repeating unit of a polymer

monosaccharide

carbohydrate monomer

nucleic acid

macromolecule storing and transmitting genetic information

nucleotide

monomer of nucleic acids containing sugar, phosphate, and base

omega fat

essential polyunsaturated fat numbered from methyl end

peptide bond

bond between amino acids formed by dehydration reaction

phosphodiester linkage

covalent bond linking nucleotides in nucleic acids

phospholipid

membrane component with glycerol, two fatty acids, and phosphate group

polymer

chain of covalently linked monomers

polynucleotide

long chain of nucleotides

polypeptide

long chain of amino acids linked by peptide bonds

polysaccharide

long monosaccharide chain, branched or unbranched

primary structure

amino acid sequence of a protein

protein

macromolecule of one or more polypeptide chains

purine

nitrogenous base type; adenine and guanine

pyrimidine

nitrogenous base type; cytosine, thymine, uracil

quaternary structure

association of multiple polypeptide subunits

ribonucleic acid (RNA)

single-stranded nucleic acid involved in protein synthesis

ribosomal RNA (rRNA)

RNA aligning mRNA and ribosome; catalyzes peptide bond formation

saturated fatty acid

hydrocarbon chain with only single bonds

secondary structure

regular intramolecular hydrogen-bonded protein structures

starch

carbohydrate storage in plants

steroid

lipid with four fused hydrocarbon rings

tertiary structure

three-dimensional protein conformation from side-chain interactions