Unit 1 (Ch. 1-5) Flashcards
essential element
a chemical element required for an organism to survive, grow, and reproduce
trace element
an element indispensable for life but required in extremely minute amounts
half-life
the amount of time it takes for 50% of a sample of a radioactive isotope to decay
radiometric dating
a method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes
valence electrons
an electron in the outermost shell
valence shell
the outermost electron shell
orbital
3 dimensional space where an electron is found 90% of the time
double bond
sharing two pairs of valence electrons
electronegativity
the attraction of a given atom for the electrons of a covalent bond
non polar covalent bond
electrons are shared equally between two atoms of similar electronegativity
polar covalent bond
a covalent bond between atoms that differ in electronegativity. the shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive.
hydrogen bond
weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule
van der Waals interactions
weak attractions between molecules or parts of molecules that result from transient local partial charges
chemical equilibrium
the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time
cohesion
the linking together of like molecules, often by hydrogen bonds. the tendency for water to stick to other water molecules.
surface tension
results from cohesion due to hydrogen bonding, how difficult it is to stretch or break the surface of a liquid
adhesion
the clinging of one substance to another
thermal energy
the kinetic energy associated with the random movement of atoms or molecules
calorie (cal)
the amount of heat it takes to raise the temperature of 1g of water by 1 degrees C
specific heat
the amount of heat that must be absorbed or lost for 1g of that substance to change its temperature by 1 degrees C
heat of vaporization
the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state
evaporative cooling
as a liquid evaporates, the surface of the liquid that remains behind cools down
solution
a liquid that is a completely homogeneous mixture of two or more substances
solvent
the dissolving agent
solute
substance that is dissolved
hydration shell
the sphere of water molecules around a dissolved ion
hydrophilic
affinity for water, polar
hydrophobic
repels water, non polar
molarity
number of moles of solute/liter of solution
hydrogen ion
a single proton with a charge of 1+
hydroxide ion
OH- with a charge of 1-
hydronium ion
a water molecule that has an extra proton bound to it
acid
substance that increase the hydrogen ion concentration of a solution
base
substance that reduces the hydrogen ion concentration
pH
-log[H+]
buffer
minimizes changes in the concentrations of H+ and OH- in a solution, minimizes changes in pH
hydrocarbons
organic molecules only consisting of carbon and hydrogen
structural isomers
one of two or more compounds that have the same molecular formula but differ in the covalent arrangement of their atoms
isomers
variation in the architecture of organic molecules
cis-trans isomers (geometric isomers)
differ in arrangement about a double bond
cis isomer
two Xs are on the same side
trans isomer
the two Xs are on opposite sides
enantiomers
differ in spatial arrangement around an asymmetric carbon, resulting in molecules that are mirror images. 4 different atoms attached to a carbon in two different organizations.
ATP
adenosine attached to a string of three phosphate groups
hydroxyl group
-OH, polar, alcohol
carbonyl group
\/C=O, ketone and aldehyde
carboxyl group
-COOH, acts as an acid, carboxylic acid and organic acid
amino group
-NH2, acts as a base, amine
sulfhydryl group
-SH, two -SH groups can react to form a “cross-link” that helps stabilize protein structure, thiol
phosphate group
-OPO3 -2, confers on a molecule the ability to react with water and release energy, organic phosphate
methyl group
-CH3, affects the expression of genes, methylated compound
macromolecules
giant molecule formed by the joining of smaller molecules. carbohydrates, proteins and nucleic acids
polymer
made up of monomers
dehydration reaction
water molecule is lost, bringing two molecules together to be covalently bonded to each other
enzymes
proteins that speed up reactions
hydrolysis
polymers being dissembled to monomers by the addition of water
carbohydrates
monosaccharides (single sugars), disaccharides (double sugars joined by a glycosidic linkage), polysaccharides (multiple sugars joined), multiple of the unit CH2O
glycosidic linkage
a covalent bond formed between two monosaccharides by a dehydration reaction
starch
a storage polysaccharide in plants consisting of entirely glucose monomers joined by glycosidic linkages
glycogen
an extensively branched glucose storage polysaccharide found in the liver and muscle of animals; animal equivalent of starch
cellulose
a structural polysaccharide of plant cell walls, consisting of glucose monomers joined by b glycosidic linkages
chitin
carbohydrate used by anthropoids to build their exoskeletons
lipids
do not include true polymers, not big enough to be considered macromolecules
fat
glycerol molecule joined to three fatty acids
saturated fatty acid
all carbons in the hydrocarbon tail are connected by single bonds, maximizing the number of hydrogen atoms that are attached to the carbon skeleton, solid at room temp
unsaturated fatty acid
has one or more double bonds between carbons in the hydrocarbon tail, reducing the number of hydrogen atoms attached to the carbon skeleton, liquid at room temp
phospholipid
made up of glycerol joined to two fatty acids as a phosphate group, the hydrocarbon chains of the fatty acids act as non polar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head
steroids
lipids characterized by a carbon skeleton consisting of four fused rings. eg. cholesterol: crucial molecule in animals
catalysts
proteins that selectively speed up chemical reactions without being consumed in the reaction
amino acids
monomer of proteins, has both an amino group and a carboxyl group, and a unique R group
peptide bond
the covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction
primary structure of a protein
sequence of amino acids
secondary structure of a protein
polypeptide chains repeatedly coiled or folded in patterns that contribute to the proteins overall shape
tertiary structure of a protein
3D shape stabilized by interactions between side chains (hydrophobic interactions, disulfide bridges, van der Waals interactions, hydrogen bonds)
quaternary structure of a protein
protein structure that results from the aggregation of polypeptide subunits
nucleic acids
polymers (polynucleotides) made up of monomers (nucleotides), two types: DNA and RNA
pyrimidine
has one six-membered ring of carbon and nitrogen atoms, C, T, and U
purines
six membered ring fused to a five membered ring, A and G
