concept of biology unit 1 ch.2 vocabulary

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anion
a negative ion formed by gaining electrons
atomic number
the number of protons in an atom
cation
a positive ion formed by losing electrons
chemical bond
an interaction between two or more of the same or different elements that results in the formation of molecules
covalent bond
a type of strong bond between two or more of the same or different elements; forms when electrons are shared between elements
electron
a negatively charged particle that resides outside of the nucleus in the electron orbital; lacks functional mass and has a charge of -1
electron transfer
the movement of electrons from one element to another
electron
one of 118 unique substances that cannot be broken down into smaller substances and retain the characteristic of that substance; each element has a specified number of protons and unique properties
hydrogen bond
a weak bond between partially positively charged hydrogen atoms and partially negatively charged elements or molecules
ion
an atom or compound that does not contain equal numbers of protons and electrons, and therefore has a net charge
ionic bond
a chemical bond that forms between ions of opposite charges
isotope
one or more forms of an element that have different numbers of neutrons
mass number
the number of protons plus neutrons in an atom
matter
anything that has mass and occupies space
neutron
a particle with no charge that resides in the nucleus of an atom; has a mass of 1
nonpolar covalent bond
a type of covalent bond that forms between atoms when electrons are shared equally between atoms, resulting in no regions with partial charges as in polar covalent bonds
nucleus
(chemistry) the dense center of an atom made up of protons and (except in the case of a hydrogen atom) neutrons
octet rule
states that the outermost shell of an element with a low atomic number can hold eight electrons
periodic table of elements
an organizational chart of elements, indicating the atomic number and mass number of each element; also provides key information about the properties of elements
polar covalent bond
a type of covalent bond in which electrons are pulled toward one atom and away from another, resulting in slightly positive and slightly negative charged regions of the molecule
proton
a positively charged particle that resides in the nucleus of an atom; has a mass of 1 and a charge of +1
radioactive isotope
an isotope that spontaneously emits particles or energy to form a more stable element
van der Waals interaction
a weak attraction or interaction between molecules caused by slightly positively charged or slightly negatively charged atoms
acid
a substance that donates hydrogen ions and therefore lowers pH
adhesion
the attraction between water molecules and molecules of a different substance
base
a substance that absorbs hydrogen ions and therefore raises pH
buffer
a solution that resists a change in pH by absorbing or releasing hydrogen or hydroxide ions
cohesion
the intermolecular forces between water molecules caused by the polar nature of water; creates surface tension
evaporation
the release of water molecules from liquid water to form water vapor
hydrophilic
describes a substance that dissolves in water; water-loving
hydrophobic
describes a substance that does not dissolve in water; water-fearing
litmus paper
filter paper that has been treated with a natural water-soluble dye so it can be used as a pH indicator
pH scale
a scale ranging from 0 to 14 that measures the approximate concentration of hydrogen ions of a substance
solvent
a substance capable of dissolving another substance
surface tension
the cohesive force at the surface of a body of liquid that prevents the molecules from separating
temperature
a measure of molecular motion
amino acid
a monomer of a protein
carbohydrate
a biological macromolecule in which the ratio of carbon to hydrogen to oxygen is 1:2:1; carbohydrates serve as energy sources and structural support in cells
cellulose
a polysaccharide that makes up the cell walls of plants and provides structural support to the cell
chitin
a type of carbohydrate that forms the outer skeleton of arthropods, such as insects and crustaceans, and the cell walls of fungi
denaturation
the loss of shape in a protein as a result of changes in temperature, pH, or exposure to chemicals
deoxyribonucleic acid (DNA)
a double-stranded polymer of nucleotides that carries the hereditary information of the cell
disaccharide
two sugar monomers that are linked together by a peptide bond
enzyme
a catalyst in a biochemical reaction that is usually a complex or conjugated protein
fat
a lipid molecule composed of three fatty acids and a glycerol (triglyceride) that typically exists in a solid form at room temperature
glycogen
a storage carbohydrate in animals
hormone
a chemical signaling molecule, usually a protein or steroid, secreted by an endocrine gland or group of endocrine cells; acts to control or regulate specific physiological processes
lipids
a class of macromolecules that are nonpolar and insoluble in water
macromolecule
a large molecule, often formed by polymerization of smaller monomers
monosaccharide
a single unit or monomer of carbohydrates
nucleic acid
a biological macromolecule that carries the genetic information of a cell and carries instructions for the functioning of the cell
nucleotide
a monomer of nucleic acids; contains a pentose sugar, a phosphate group, and a nitrogenous base
oil
an unsaturated fat that is a liquid at room temperature
phospholipid
a major constituent of the membranes of cells; composed of two fatty acids and a phosphate group attached to the glycerol backbone
polypeptide
a long chain of amino acids linked by peptide bonds
polysaccharide
a long chain of monosaccharides; may be branched or unbranched
protein
a biological macromolecule composed of one or more chains of amino acids
ribonucleic acid (RNA)
a single-stranded polymer of nucleotides that is involved in protein synthesis
saturated fatty acid
a long-chain hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached to the carbon skeleton is maximized
starch
a storage carbohydrate in plants
steroid
a type of lipid composed of four fused hydrocarbon rings
trans-fat
a form of unsaturated fat with the hydrogen atoms neighboring the double bond across from each other rather than on the same side of the double bond
triglyceride
a fat molecule; consists of three fatty acids linked to a glycerol molecule
unsaturated fatty acid
a long-chain hydrocarbon that has one or more than one double bonds in the hydrocarbon chain