Chapter 2 Flashcards
matter
anything that occupies space and has mass.
mass
the amount of matter in an object
weight
the gravitational force acting on an object of a given mass.
kilogram ( kg )
the international unit for mass
gram (g)
1/1000 the mass of a kilogram
element
the simplest type of matter, having unique chemical properties.
atom
the smallest particle of an element that has the chemical characteristics of that element.
neutron
has no electrical charge
proton
has one positive charge
electron
has one negative charge
nucleus
protons and neutrons form the nucleus at the center of an atom; electrons move around the nucleus; nucleus accounts for 99.97% of an atom’s mass but only 1 ten-trillionth of its volume; most of the volume of an atom is occupied by the electrons.
electron cloud
the region where the electron is most likely to be found
atomic number
equal to the number of protons in each atom and, because the number of electrons is equal to the number of protons,
the atomic number is also the number of electrons.
mass number
the number of protons plus the number of neutrons in each atom.
Isotopes
two or more forms of the same element that have the same number of protons and electrons but a different number of neutrons
dalton (Da)
a system of relative atomic mass scientists use to avoid working with such small numbers; unified atomic mass unit ( u ) is 1/12 the mass of 12 C, a carbon atom with 6 protons and 6 neutrons. Thus, 12 C has an atomic mass of exactly 12 Da.
atomic mass
the average mass of an element’s naturally occurring isotopes, taking into account the relative abundance of each isotope.
Avogadro’s number or 1 mole (mol)
chemist groups atoms in lots of 6.022 x 10 ^23
molar mass
The mass of 1 mole of a substance expressed in grams
chemical bonding
When the outermost electrons are transferred, or shared, between atoms; the outermost electrons of an atom determine its chemical behavior.
ion
a charged particle, formed when an atom loses or gains electrons resulting in unequal numbers of protons and electrons
cations
Positively charged ions
anions
negatively charged ions
ionic bond
a bond when a cation and anion is bonded together; cations and anions tend to remain close together because oppositely charged ions are attracted to each other
covalent bond
forms when atoms share one or more pairs of electrons; the resulting combination of atoms is called a molecule.
single covalent bond
the sharing of one pair of electrons by two atoms
double covalent bond
when two atoms share 4 electrons, 2 from each atom; Double covalent bonds are indicated by a double line between the atoms
nonpolar covalent bonds
when electrons are shared equally between atoms
polar covalent bonds
when elections are not shared equally between atoms; atoms bound to one another by a covalent bond do not
always share their electrons equally because the nucleus of one atom attracts the electrons more strongly than does the nucleus of the other atom
molecule
composed of two or more atoms chemically combined to form a structure that behaves as an independent unit.
compound
a substance resulting from the chemical combination of two or more different types of atoms.
Alpha particles
positively charged helium ions which consist of 2 protons and 2 neutrons.
Beta particles
electrons formed as neutrons change into protons. An electron is ejected from the neutron, and the proton that is produced remains in the
nucleus.
Gamma rays
a form of electromagnetic radiation (high-energy photons) released from nuclei as they lose energy.
molecular mass
can be determined by adding up the atomic masses of its atoms (or ions).
intermolecular forces
Weak electrostatic attractions that exist between the oppositely charged parts of molecules, or between ions and molecules
hydrogen bond
If the positively charged hydrogen of one molecule is attracted to the negatively charged oxygen, nitrogen, or fluorine of another molecule
Solubility
the ability of one substance to dissolve in another
dissociate
separate; When ionic compounds dissolve in water, their ions dissociate from one another because the cations are attracted to the negative ends of the water molecules, and the anions are attracted to the positive ends of the water molecules.
electrolytes
Cations and anions that dissociate in water; have the capacity to conduct an electrical current
nonelectrolytes
Molecules that do not dissociate form solutions that do not conduct electricity
chemical reaction
when atoms, ions, molecules, or compounds interact either to form or to break chemical bonds.
reactants
The substances that enter into a chemical reaction
products
the substances that result from the chemical reaction
When two or more reactants chemically combine to form a new
and larger product, the process is called a synthesis reaction .
When two or more reactants chemically combine to form a new
and larger product, the process is called a synthesis reaction .
dehydration reactions
Synthesis reactions in which water is a product
anabolism
All of the synthesis reactions that occur within the body; The growth, maintenance, and repair of the body could not take place without anabolic reactions.
decomposition reaction
reverse of a synthesis reaction; a larger reactant is chemically broken down into two or more smaller products.
hydrolysis reactions
reactions that require water to be split into two parts and that each part be contributed to one of the new molecules.
catabolism
The decomposition reactions that occur in the body
metabolism
All of the anabolic and catabolic reactions in the body
reversible reaction
when the reaction can proceed from reactants to products or from products to reactants.
equilibrium
When the rate of product formation is equal to the rate of the reverse reaction
oxidation
The loss of an electron by an atom
reduction
gain of an electron
oxidation-reduction reactions
when one atom partially or completely loses an electron and another atom gains that electron
Energy
the capacity to do work; to move matter.
Potential energy
stored energy that could do work but is not doing so.
Kinetic energy
the form of energy that is actually doing work and moving matter.
Mechanical energy
results from the position or movement of objects.
chemical energy
the potential energy stored within its chemical bonds.
Heat energy
the energy that flows between objects that are at different temperatures.
Activation energy
the minimum amount of energy that the reactants must have to start a chemical rxn
catalysts
substances that increase the rate of chemical reactions without being permanently changed or depleted themselves.
enzymes
proteins that act as catalysts.
Inorganic chemistry
generally deals with substances that do not contain carbon; lack of carbon-hydrogen bonds.
Organic chemistry
study of carbon-containing substances, however, carbon monoxide, carbon dioxide, and bicarbonate ions, which lack C—H bonds, are classified as inorganic molecules.
water
one atom of oxygen joined to two atoms of hydrogen by covalent bonds.
cohesion
attraction of water to another water molecule
adhesion
when the same attractive force of hydrogen bonds with water and also attracts other molecules
mixture
a combination of two or more substances physically blended together, but not chemically combined.
solution
any mixture of liquids, gases, or solids in which the substances are uniformly distributed with no clear boundary between them.
solute
dissolves in the solvent .
solvent
substance the solute dissolves in
colloid
a mixture in which a dispersed (solute-like) substance is distributed throughout a dispersing (solventlike)
substance.
suspension
a mixture containing materials that separate from each other unless they are continually, physically blended together.
osmole
Avogadro’s number of particles of a substance in 1 kilogram (kg) of water.
osmolality
reflects the number, not the type, of particles in a solution.
milliosmole
1/1000 of an osmole.
acid
proton donor.
base
proton acceptor, and any substance that binds to (accepts) H+ is a base.
pH scale
means of referring to the H+ concentration in a solution; 0-14 range
neutral solution
pH of 7; pure water; equal concentrations of H+ and OH-
acidic
Solutions with a pH less than 7; greater concentration of H+ than OH-
alkaline; basic
Solutions with a pH greater than 7; fewer H+ than OH-
Acidosis
results if blood pH drops below 7.35, in which case the nervous system becomes depressed and the individual may become disoriented and possibly comatose.
alkalosis
results if blood pH rises above 7.45. Then the nervous system becomes overexcitable, and the individual may become extremely nervous or have convulsions.
salt
a compound consisting of a cation other than H+ and an
anion other than OH-
buffers
chemicals that resist changes in solution pH when either acids or bases are added.
conjugate acid-base pairs
A conjugate base is what remains of an acid after the H+ (proton) is lost. A conjugate acid is formed when a H + is transferred to the conjugate base. Two substances related
in this way are a conjugate acid-base pair.
Oxygen (O2)
an inorganic molecule consisting of two oxygen atoms bound together by a double covalent bond.
Carbon dioxide (CO2)
consists of one carbon atom bound to two oxygen atoms.; produced when organic molecules are metabolized within the cells of the body
Carbohydrates
composed primarily of carbon, hydrogen, and oxygen atoms and range in size from small to very large; approx two hydrogen atoms and one oxygen atom for each carbon atom.
monosaccharides
simple sugars.
isomers
molecules that have the same number and types of atoms but differ in their three-dimensional arrangement
Disaccharides
composed of two simple sugars bound together through a dehydration reaction.
sucrose
Glucose and fructose combine to form the disaccharide sucrose plus a molecule of water
polysaccharides
consist of many monosaccharides bound together to form long chains that are either straight or branched.
Glycogen
animal starch; polysaccharide composed of many glucose molecules
starch
Plants use starch as an energy-storage molecule in the same way that animals use glycogen; When humans ingest plants, the starch can be broken down and used as an energy source.
cellulose
cellulose is an important structural component of plant cell walls; Humans do not have the digestive enzymes necessary to break down cellulose so it is eliminated in the feces, where it provides bulk.
lipids
organic molecules; composed principally of carbon, hydrogen, and oxygen; lower ratio of oxygen to carbon than do carbohydrates, which makes them less polar.
Triglycerides
consist of two different types of building blocks: one glycerol and three fatty acids.
Glycerol
3- carbon molecule with a hydroxyl group attached to each carbon atom, and each fatty acid consists of a straight chain of carbon atoms with a carboxyl group attached at one end
carboxyl group
consists of both an oxygen atom and a hydroxyl group attached to a carbon atom; responsible for the acidic nature of the molecule because it releases hydrogen ions into solution.
saturated fatty acid
contains only single covalent bonds between the carbon atoms
unsaturated
has one or more double covalent bonds between carbon atoms
Monounsaturated fats
have one double covalent bond between carbon atoms
Polyunsaturated fats
have two or more double covalent bonds between carbon atoms.
Trans fats
unsaturated fats that have been chemically altered by the addition of H atoms.
Phospholipids
one of the fatty acids bound to the glycerol is replaced by a molecule containing phosphate and, usually, nitrogen; polar at the end of the molecule to which the phosphate
is bound and nonpolar at the other end.
hydrophilic
water-loving
hydrophobic
water-fearing
eicosanoids
group of important chemicals derived from fatty acids; prostaglandins, thromboxanes, and leukotrienes
Prostaglandins
regulate the secretion of certain hormones, blood clotting, some reproductive functions, and many other processes.
steroids
composed of carbon atoms bound together into four
ringlike structures; cholesterol, bile salts, estrogen, progesterone, and testosterone.
fat-soluble vitamins
nonpolar molecules essential for many normal body functions.
proteins
contain carbon, hydrogen, oxygen, and nitrogen bound together by covalent bonds, and most proteins contain
some sulfur.
amino acid molecules
has an amine group, a carboxyl group, a hydrogen atom, and a side chain designated by the symbol R attached to the same carbon atom.
peptide bonds
Covalent bonds formed between amino acid molecules during protein synthesis
primary structure of a protein
determined by the sequence of the amino acids bound by peptide bonds
secondary structure
results from the folding or bending of the polypeptide chain caused by the hydrogen bonds between amino acids
denaturation
when hydrogen bonds that maintain the shape of the protein are broken, the protein becomes nonfunctional
tertiary structure
results from folding of the pleated sheets or helices
domain
a folded sequence of 100–200 amino acids within a protein
quaternary structure
results from the spatial relationships between the individual subunits
enzyme
protein catalyst that increases the rate at which a chemical reaction proceeds without the enzyme being permanently
changed.
lock-and-key model of enzyme action
a reaction occurs when the reactants (key) bind to the active site (lock) on the enzyme.
induced fit model
the enzyme is able to change shape slightly and better fit the reactants.
cofactors
nonprotein substances needed by enzymes to be functional; ion or organic molecule
coenzymes.
Cofactors that are organic molecules, such as certain vitamins
nucleic acids
large molecules composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus.
Deoxyribonucleic acid (DNA)
the genetic material of cells, and copies of DNA are transferred from one generation of cells to the next generation.
Ribonucleic acid (RNA)
structurally related to DNA, and three types of RNA also play important roles in protein synthesis.
nucleotides
Both DNA and RNA consist of these basic building blocks composed of a monosaccharide to which a nitrogenous organic base and a phosphate group are attached
5-carbon monosaccharide
deoxyribose for DNA; ribose for RNA.
Complementary base pairs
organic bases held together by hydrogen bonds.
antiparallel
The two nucleotide strands of a DNA molecule are antiparallel; the two strands lie side by side, but their sugar-
phosphate “backbones” extend in opposite directions because of the orientation of their nucleotides
gene
A sequence of DNA bases that directs the synthesis of proteins or RNA molecules
Adenosine triphosphate (ATP)
especially important organic molecule in all living organisms; consists of adenosine (the sugar ribose with the organic base adenine) and three phosphate groups; ATP is often called the energy currency of cells because it is capable of both storing and providing energy.
