Kapitel 2 Flashcards
Positively charged ion generated by the removal of an electron from a hydrogen atom; often used to refer to a proton (H+) in aqueous solution. Its presence is the basis of acidity.
hydrogen ion
amino group
Functional group (–NH2) derived from ammonia. Can accept a proton and carry a positive charge in aqueous solution.
One of two or more substances that contains the same atoms and has the same molecular formula (such as C6H12O6) as the other - but differs from the other in the spatial arrangement of these atoms. Optical isomers are mirror images of each other.
isomer (stereoisomer)
aldehyde
Reactive organic compound that contains the HC=O group - for example - glyceraldehyde.
hydrogen bond
A weak noncovalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom - such as nitrogen or oxygen - in another; these interactions are key to the structure and properties of water.
nucleic acid
Macromolecule that consists of a chain of nucleotides joined together by phosphodiester bonds; RNA or DNA.
hydrolysis
Chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water (its –H being added to one product of the cleavage and its –OH to the other); the reverse of condensation.
In chemistry - describes a molecule or bond in which electrons are distributed unevenly.
polar
The strength of the chemical linkage between two atoms - measured by the energy in kilocalories needed to break it.
bond energy
Chemical group consisting of a hydrogen atom linked to an oxygen - as in an alcohol.
hydroxyl (–OH)
Avogadro’s number
The number of molecules in a mole - the quantity of a substance equal to its molecular weight in grams; approximately 6 × 1023.
Molecule made of a nitrogen-containing ring compound attached to a sugar - either ribose (in RNA) or deoxyribose (in DNA).
nucleoside
condensation reaction
Chemical reaction in which a covalent bond is formed between two molecules as water is expelled; used to build polymers - such as proteins - polysaccharides - and nucleic acids.
phosphodiester bond
Strong covalent bond that forms the backbone of DNA and RNA molecules; links the 3′ carbon of one sugar to the 5′ carbon of another.
Chemical reaction that involves cleavage of a covalent bond with the accompanying consumption of water (its –H being added to one product of the cleavage and its –OH to the other); the reverse of condensation.
hydrolysis
polynucleotide
A molecular chain of nucleotides chemically linked by a series of phosphodiester bonds. A strand of RNA or DNA.
ion
An atom carrying an electrical charge - either positive or negative.
methyl (–CH3) group
Hydrophobic chemical group derived from methane (CH4).
The amount of a substance - in grams - that is equal to its molecular weight; this quantity will contain 6 × 1023 molecules of the substance.
mole
nucleotide
Basic building block of the nucleic acids - DNA and RNA; includes a nucleoside with a series of one or more phosphate groups linked to its sugar.
atomic mass
The mass of an atom expressed in daltons - the atomic mass unit that closely approximates the mass of a hydrogen atom.
lipid bilayer
Thin pair of closely juxtaposed sheets - composed mainly of phospholipid molecules - that forms the structural basis for all cell membranes.
The linear order of monomers in a large molecule - for example amino acids in a protein or nucleotides in DNA; encodes information that specifies a macromolecule’s precise biological function.
sequence
Hydrophobic chemical group derived from methane (CH4).
methyl (–CH3) group
organic molecule
Chemical compound that contains carbon and hydrogen.
solute
Any substance that is dissolved in a liquid. The liquid is called the solvent.
Substance that cannot be broken down to any other chemical form; composed of a single type of atom.
element
Molecule containing an amino group (–NH2).
amine
pH scale
Concentration of hydrogen ions in a solution - expressed as a logarithm. Thus - an acidic solution with pH 3 will contain 10–3 M hydrogen ions.
monomer
Small molecule that can be linked to others of a similar type to form a larger molecule (polymer).
ionic bond
Interaction formed when one atom donates electrons to another; this transfer of electrons causes both atoms to become electrically charged.
The number of electrons an atom must gain or lose (either by electron sharing or electron transfer) to achieve a filled outer shell. For example - Na must lose one electron - and Cl must gain one electron. This number is also equal to the number of single bonds that the atom can form.
valence
Carbon atom linked to an oxygen atom by a double bond.
carbonyl group
hydrophobic interaction
Type of noncovalent bond that forces together the hydrophobic portions of dissolved molecules to minimize their disruption of the hydrogen-bonded network of water; helps push together membrane phospholipids and fold proteins into a compact - globular shape.
carboxyl group
Carbon atom linked to an oxygen atom by a double bond and to a hydroxyl group (–COOH). In aqueous solution - acts as a weak acid.
Linear or branched polymer composed of sugars. Examples are glycogen - hyaluronic acid - and cellulose.
polysaccharide
polysaccharide
Linear or branched polymer composed of sugars. Examples are glycogen - hyaluronic acid - and cellulose.
Unit of molecular mass. Defined as one-twelfth the mass of an atom of carbon 12 (1.66 × 10-24 g); approximately equal to the mass of a hydrogen atom.
dalton
See DNA
deoxyribonucleic acid
kilocalorie (kcal)
Unit of heat equal to 1000 calories. Often used to express the energy content of food or molecules: bond strengths - for example - are measured in kcal/mole. An alternative unit in wide use is the kilojoule.
amine
Molecule containing an amino group (–NH2).
Small molecule that can be linked to others of a similar type to form a larger molecule (polymer).
monomer
Interaction formed when one atom donates electrons to another; this transfer of electrons causes both atoms to become electrically charged.
ionic bond
kilojoule (kJ)
Standard unit of energy equal to 0.239 kilocalories.
Any substance that is dissolved in a liquid. The liquid is called the solvent.
solute
Nonpolar - uncharged molecule or part of a molecule that forms few or no hydrogen bonds with water molecules and therefore does not dissolve; literally - “water fearing.”
hydrophobic
Molecule or part of a molecule that readily forms hydrogen bonds with water - allowing it to dissolve; literally - “water loving.”
hydrophilic
anion
Negatively charged ion - such as Cl- or CH3COO-.
calorie
Unit of heat. Equal to the amount of heat needed to raise the temperature of 1 gram of water by 1°C.
Chemical association that does not involve the sharing of electrons; singly are relatively weak - but can sum together to produce strong - highly specific interactions between molecules. Examples are hydrogen bonds and van der Waals attractions.
noncovalent bond
covalent bond
Stable chemical link between two atoms produced by sharing one or more pairs of electrons.
hydroxyl (–OH)
Chemical group consisting of a hydrogen atom linked to an oxygen - as in an alcohol.
conformation
Precise - three-dimensional shape of a protein or other macromolecule - based on the spatial location of its atoms in relation to one another.
carbohydrate
General term for sugars and related compounds with the general formula (CH2O)n.
bond energy
The strength of the chemical linkage between two atoms - measured by the energy in kilocalories needed to break it.
Small organic molecule containing both an amino group and a carboxyl group; it serves as the building block of proteins.
amino acid
Molecule that serves as the principal carrier of energy in cells; this nucleoside triphosphate is composed of adenine - ribose - and three phosphate groups.
ATP (adenosine 5′-triphosphate)
hydrophobic
Nonpolar - uncharged molecule or part of a molecule that forms few or no hydrogen bonds with water molecules and therefore does not dissolve; literally - “water fearing.”
trans
Beyond - or on the other side.
isotope
A variant of an element that has the same number of protons but a different atomic weight. Some are radioactive.
cis
On the same side as.
dalton
Unit of molecular mass. Defined as one-twelfth the mass of an atom of carbon 12 (1.66 × 10-24 g); approximately equal to the mass of a hydrogen atom.
A weak noncovalent interaction between a positively charged hydrogen atom in one molecule and a negatively charged atom - such as nitrogen or oxygen - in another; these interactions are key to the structure and properties of water.
hydrogen bond
A double-ringed - nitrogen-containing compound found in DNA and RNA. Examples are adenine and guanine.
purine
fatty acid
Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain. Used as a major source of energy during metabolism and as a starting point for the synthesis of phospholipids.
Molecule that consists of a carboxylic acid attached to a long hydrocarbon chain. Used as a major source of energy during metabolism and as a starting point for the synthesis of phospholipids.
fatty acid
Mixture of weak acids and bases that maintains the pH of a solution by releasing and taking up protons.
buffer
Thin pair of closely juxtaposed sheets - composed mainly of phospholipid molecules - that forms the structural basis for all cell membranes.
lipid bilayer
Prefix that denotes a short polymer (oligomer). May be made of amino acids (oligopeptide) - sugars (oligosaccharide) - or nucleotides (oligonucleotide).
oligo-
The branch of chemistry concerned with compounds made of carbon. Includes essentially all of the molecules from which living cells are made - apart from water and metal ions such as Na+.
organic chemistry
