matter
all tangible materials that occupy space and have mass
G-11
atom
the smallest particle of an element to retain all the properties of that element.
G-2
proton
a elementary particle that carries a postive charge. It is identical to the nucleus of the hydrogen atom.
G-14
neutrons
a electrically neutral particle in the nuclei of all atoms except hydrogen.
G-12
electrons
a negatively charged subatomic particle that is distributed around the nucleus in an atom.
G-5
nucleus
the central core of an atom, composed of protons and neutrons
G-12
atomic number (AN)
a measurement that reflects the number of protons in an atom of a particular element.
G-2
mass number (MN)
measurement that reflects the number of protons and neutrons in an atom of a particular element.
G-10
Isotope
a version of an element that is virtually identical in all chemincal properties to another version except that their atoms have slightly different atomic masses.
G-9
atomic mass or weight
the average of the mass numbers of all the isotopic forms for a particular element.
G-2
orbitals
the pathways of electrons as they rotate around the nucleus of an atom.
G-12
molecule
little mass: a distinct chemical substance that results from the combination of two or more atoms.
G-11
Ch2-p32
compounds
molecules that are a combination of two or more different elements.
G-4
molecular weight (MW) or formula mass
the weight of a molecule; which is calculated fromt he sum of all of the atomic masses of the atoms it contains.
ch2-p32
chemical bonds
a link formed between molecules when two or more atoms share, donate, or accept electrons.
G-3
valence
the combining power of an atom based upon the number of electrons it can either take on or give up.
G-18
Ch2-p32: strength, The binding qualities of an atom dictated by the number of electrons in its outermost shell.
Covalent bonds
cooperative valence - a chemical bond formed by the sharing of electrons between two atoms.
G-4
polar
term to describe a molecule with an asymmetrical distribution of charges. Such a molecule has a negative pole and a positive pole.
G-13
nonpolar
a term used to describe an electrically neutral molecule formed by the covalent bonds between atoms that have the same or similar electronegativity.
G-12
ionic bonds
a chemical bond in which electrons are transferred and not shared between atoms.
G-9
ionization
the aqueous dissociation of an electrolyte into ions.
G-9
ion
an unattached, charged particle.
G-9
cations
a positively charged ion, that migrates toward the negative pole or cathode of an electrical field.
Ch2-p34 & G-3
anions
a negatively charged ion that migrates toward the positive pole or anode.
Ch2-p34 & G-1
electrolytes
any compound that ionizes in solution and conducts current in an electrical field.
G-5
hydrogen bond
a weak chemical bond formed by the attraction of forces between molecules or atoms - in this case, hydrogen and either oxygen or nitrogen. In this type of bond, electrons are not shared, lost or gained.
G-8
Vander Waals forces
weak molecular interactions similar to hydrogen bonds that play major roles in the shape and function of biological molecules.
Ch2-p35
oxidation reduction reaction (REDOX)
Redox-reactions, in which paired sets of molecules participate in electron transfers.
G-12
reducing agent
an atom such as sodium that can donate electrons and thereby reduce another atom.
Ch2-35
oxidizing agent
an atom that can receive extra electrons and thereby oxidize another molecule.
Ch2-p35
chemical reactions
changes in the composition of the matter that molecules, including those in cells. These changes generally involve the breaking and making of bonds and the rearrangement of atoms.
Ch2-p36
reactants
molecules entering or starting a chemical reaction.
G-14
products
The substances that result from the reaction.
Ch2-p36
chemical equation
Used by chemists and biologists as a form of shorthand to summarize the content of a reaction.
Ch2-p36
synthesis reaction
the reactants bond together in a manner that produces an entirely new molecule.
Ex: Reactant A + Reactant B = Product AB
Ch2-p36
exchange reactions
the reactants trade portions between each other and release products that are combinations of the two.
Ex: AB + XY = AY + XB
Ch2-p37
decomposition reactions
the bonds on a single reactant molecule are permanently broken to release two or more product molecules.
Ch2-p36
catalysts
a substance that alters the rate of a reaction without being consumed or permanently changed by it. In cells, enzymes are catalysts.
G-3
solution or solute
a mixture of one or more substances (solutes) that cannot be separated by filtration or ordinary settling.
G-16
solvent
a dissolving medium.
G-16
hydrated or hydration
the addition of water as in the coating of ions with water molecules as ions enter into aqueous solution.
G-8
hydrophilic
the property of attracting water or molecules that attract water to their surface.
G-8
hydrophobic
the property of repelling water or molecules that repel water.
G-8
amphipathic
(mphi, both) relating to a compound that has contrasting characteristics, such as hydrophilic - hydrophobic or acid-base.
G-1
concentration
the expression of the amount of a colute dissolved in a certain amount of colvent. It may be defined by weight, volume or percentage.
G-4
hydrogen ion
is positively charged because it is essentially a hydrogen that has lost its electron.
Ch2-p38
hydroxide ion
is negatively charged because it remains in possession of that electron.
Ch2-p38
acidic
a solution with a pH value below 7 on the pH scale.
G-1
basic
a solution with a pH value above 7 on the pH scale.
G-2
alkaline
another term used interchangeably with basic.
ch2-p38
pH
The symbol for the negative logarithm of the H ion concentration; p (power) or [H+]10. A system for rating acidity and alkalinity.
G-13
neutrality
Is the midpoint (pH 7) of the pH scale.
Ch2-p39
neutralization
the process of combining an acid and base until they reach a balanced proportion, with a pH value close to 7.
G-12
metabolism
a general term referring to the totality of chemical and physical processes occurring in the cell.
G-11 & Ch2-p39
inorganic chemicals
molecules that lack the basic framework of the elements of carbon and hydrogen.
G-9
organic chemicals
molecules that contain the basic framework of the elements carbon and hydrogen.
G-12
functional groups
in chemistry, a particular molecular combination that reacts in predictable ways and confers particular properties on a compound.
Ex: —COOH, —OH, —CHO.
G-7
biochemistry
the study of organic compounds produced by (or components of) living things. The four main categories of biochemicals are carbohydrates, lipids, proteins, and nucleic acid.
G-3
macromolecules
large, molecular compounds assembled from smaller subunits, most notably biochemicals.
G-10
monomers
a simple molecule that can be linked by chemical bonds to form larger molecules.
G-11
Ch2-p41: mono, one, and meros, part
polymers
a macromolecule made up of a chain of repeating units. Ex: starch, protein and DNA.
G-14
(poly, many; also the root for polysaccharide and polypeptide)Ch2-p41
carbohydrate
a compound containing primarily carbon, hydrogen, and oxygen in a 1:2:1 ratio.
G-3
ketones or aldehydes
a sugar such as glucose with a terminal cabonyl group bonded to a hydrogen and another carbon.
Ch2-41
saccharide
scientific term for sugar. Refers to a simple carbohydrate with a sweet taste.
G-15
Ch2-p41: sakcharon, sweet
monosaccharide
a simple sugar such as glucose that is a basic building block for more complex carbohydrates.
G-11
disaccharide
a sugar containing two monosaccharides.
Ex: sucrose (fructose + glucose).
G-5
polysaccharide
a carbohydrate that can be hydrolyzed into a number of monosaccharides.
Ex: cellulose, starch, and glycogen.
G-14
hexose
a 6-carbon sugar such as glucose and fructose.
G-8
pentose
a monosaccharide with five carbon atoms per molecule. Ex: arabinose, ribose and xylose.
G-13
glucose
one of the carbohydrates commonly referred to as sugars. Glucose is characterized by its 6-carbon structure.
G-7
frutose
one of the carbohydrates commonly referred to as sugars. Fructose is commonly fruit sugars.
G-7
lactose
one of the carbohydrates commonly referred to as sugars. Lactose is commonly found in milk.
G-10
maltose
one of the carbohydrates referred to as sugars. A fermentable sugar formed from starch.
G-10
sucrose
one of the carbohydrates commonly referred to as sugars. Commonly table or cane sugar.
G-17
glycosidic bonds
a bond that joins monosaccharides to form disaccharides and polymers.
G-7
dehydration synthesis
during the formation of a carbohydrate bond, the step in which one carbon molecule gives up its OH group and the other loses the H from its OH group, thereby producing a water molecule. This process is common to all polymerization reactions.
G-5
cellulose
a long, fibrous polymer composed of ß-glucose; one of the most common substances on earth.
G-3
agar
a polysaccharide found in seaweed and commonly used to prepare solid culture media.
G-1
chitin
a polysaccharide similar to cellulose om chemical structure. This polymer makes up the horny substance of the exoskeletons of arthropods and certain fungi.
G-4
peptidoglycan
a network of polysaccharide chains cross-linked by short peptides that forms the rigid part of the bacterial cell walls. Gram-negative bacteria have a smaller amount of this rigid structure than do gram-positive bacteria.
G-13
lipopolysaccharide (LPS)
a molecular complex of lipids and carbohydrate found in the bacterial cell wall. The lipopolysaccharide (LPS) of gram negatve bacteria is an endotoxin with generalized pathologic effects sich as fever.
G-10
glycocalyx
a filamentous network of carbohydrate-rich molecules that coats cells.
G-7
Ch2-p45: glycos, sweet, and calyx, covering
starch or glycogen
Polysaccharides are usually stored by cells in the form of glucose polymers that are readily tapped as a source of energy and other metabolic needs.
Ch2-p45
hydrolysis
a process in which water is used to break bonds in molecules. Usually occurs in conjunction with an enzyme.
G-8
Ch2-p45: hydro, water, and hydrein, to dissolve
lipid
a term used to describe a variety of substances that are not soluble in polar solvents such as water but will dissolve in nonpolar solvents such as benzene and chloroform. Lipids include triglycerides, phospholipids, steroids, and waxes.
G-10
triglyceride
a type of lipid composed of a glycerol colecule bound to three fatty acids.
G-18
fatty acids
long chain unbranched hydrocarbon molecules with a caboxyl group (COOH) at one end that is free to bind to the glycerol.
Ch2-p45
ester bond
a covalent bond formed by reacting carboxylic acid with an OH group.
O
║
(R-C-O-R')
(Olive and corn oils, lard, and butter are examples of triacylglycerols - esters formed between glycerol and three fatty acids.
G-6
phospholipids
a class of lipids that compose a major structural component of cell membranes.
G-13
cholesterol
best known member of a group of lipids called steroids. Cholesterol is commonly found in cell membranes and animal hormones.
G-4
proteins
predominant organic molecule in cells, formed by long chains of amino acids.
G-14
amino acids
the building blocks of protein. Amino acids exist in 20 naturally occurring forms that impact different characteristics to the various proteins they compose.
G-1
peptide bond
the covalent union between two amino acids that forms between the amine group of one and the carboxyl group of the other. The basic bond of proteins.
G-13
peptide
molecule composed of short chains of amino acids, such as a dipeptide (two amino acids), a tripeptide (three) and a tetrapeptide (four).
G-13
Ch2-p49: (pepsis, digestion)
polypeptide
a relatively large chain of amino acids linked by peptide bonds.
G-14
primary(1°)structure
Initial protein organization described by type, number, and order of amino acids in the chain. The primary structure varies extensively from protein to protein.
G-14
secondary(2°)structure
protein structure that occurs when the functional groups on the outer surface of the molecule interact by forming hydrogen bonds. These bonds cause the amino acid chain either to twist, forming a helix, or to pleat into an accordion pattern called a ß-pleated sheet.
G-16
tertiary(3°)structure
protein structure that results from additional bonds forming between functional groups in a secondary structure, creating a three dimensional mass.
G-17
quaternary(4°)structure
most complex protein structure characterized by the formation of large, multiunit proteins by more than one of the polypeptides. This stucture is typical of antibodies and some enzymes that act in cell synthesis.
G-14
enzymes
a protein biocatalyst that facilitates metabolic reactions.
G-6
antibodies
a large protein molecule evoked in response to an antigen that interacts specifically with that antigen.
G-2
deoxyribonucleic acid (DNA)
the nucleic acid often referred to as the "double helix." DNA carries the master plan for an organism's herdity.
G-5
ribonucleic acid (RNA)
the nucleic acid responsible for carrying out the hereditary program transmitted by an organism's DNA.
G-15
nucleotide
the basic structure unit of DNA and RNA; each nucleotide consists of a phosphate, a sugar (ribose in RNA, deoxyribosein DNA), and a nitrogenous base such as adenine, guanine, cytosine, thymine (DNA only) or uracil (RNA only).
G-12
Ch2-p51: from nucleus and acid
nitrogen base
a ringed compound f which pyrimidines and purines are types.
G-12
adenine (A)
one of the nitrogen bases found in DNA and RNA, with a purine form.
G-1
guanine (G)
one of the nitrogen bases found in DNA and RNA in the purine form.
G-8
thymine (T)
one of the nitrogen bases found in DNA but not in RNA. Thymine is in a pyrimidine form.
G-17
cytosine (C)
One of the nitrogen bases found in DNA and RNA, with a pyrimindine form.
G-5
uracil (U)
one of the nitrogen bases in RNA but not in DNA. Uracil is in a pyrimindine form.
G-18
replication
in DNA synthesis, the semiconservative mechanisms that ensure precise duplication of parent DNA strands.
G-15
Ch2-p52: a process that makes an exact copy.
adenosine triphosphate (ATP)
a nucleotide that is the primary source of energy to cells.
G-1