Chapter 2 Flashcards
Proton
positively charged subatomic particle that occurs in the nucleus of all atoms
Neutron
uncharged subatomic particle that occurs in the atomic nucleus
Electron
negatively charged subatomic particle
Atomic Number
number of protons in the atomic nucleus; defines the element
Elements
a pure substance that consists only of atoms with the same number of protons
Isotopes
forms of an element that differ in the number of neutrons
Mass Number
of an isotope, the total number of protons and neutrons in the atomic nucleus
Radioisotope
an isotope with an unstable nucleus
Radioactive Decay
process in which atoms of a radioisotope emit energy and subatomic particles when their nucleus spontaneously breaks up
Tracer
a substance that can be traced via its detectable component
Shell Model
conceptual diagram of electron distribution in an atom
Free Radicals
atom with an unpaired electron. Most are highly reactive and can damage biological molecules (such as DNA)
Ions
an atom or molecule that carries a net charge
Chemical Bond
a strong attractive force between two atoms; links atoms in molecules
Compound
molecule that has atoms of more than one element
Ionic Bond
type of chemical bond in which a strong mutual attraction links ions of opposite charge
Covalent Bond
type of chemical bond in which two atoms share electrons
Polarity
separation of charge into positive and negative regions
Hydrogen Bond
attraction between a covalently bonded hydrogen atom and another atom taking part in a separate covalent bond
Solvent
liquid in which other substances dissolve
Hydrophilic
describes a substance that dissolves easily in water
Solute
a dissolved substance
Salt
ionic compound that releases ions other than H+ and OH- when it dissolves in water
Solution
uniform mixture of solute completely dissolved in a solvent
Concentration
amount of solute per unit volume of solution
Hydrophobic
describes a substance that resists dissolving in water
Temperature
measure of molecular motion
Cohesion
property in which the molecules of a substance resist separating from one another
Evaporation
transition of liquid to a vapor
pH
measure of the amount of hydrogen ions in a fluid
Acid
substance that releases hydrogen ions in water
Base
substances that accepts hydrogen ions in water
Buffer
set of chemicals that can keep the pH of a solution stable by alternately donating and accepting ions that contribute to pH
Organic
describes a compound that consists mainly of carbon and hydrogen atoms
Monomers
molecule that is a subunit of polymers
Polymer
molecule that consists of multiple monomers
Reaction
process of molecular change
Metabolism
collective term for all of the enzyme-mediated chemical reactions in a cell
Enzymes
organic molecule (protein or RNA) that speed up a reaction without being changed by it
Carbohydrates
Molecule that consists primarily of carbon, hydrogen, and oxygen atoms in a ratio of approximately 1:2:1
Cellulose
tough, insoluble polysaccharide that is the major structural material in plants
Lipids
fatty, oily, or waxy organic compound; e.g., a triglyceride, steroid, or wax
Fatty Acid
lipid that consists of a (hydrophilic) car-boxyl group “head” and a (hydrophobic) “tail”
Saturated Fatty Acid
fatty acid with only single bonds linking the carbons in its tail
Unsaturated Fatty Acid
fatty acid that has at least one double bond between carbons making up its tail
Triglyceride
a lipid with three fatty acid tails bonded to a glycerol; a fat
Fat
a triglyceride
Saturated Fat
triglyceride with three saturated fatty acid tails
Unsaturated Fats
triglyceride molecule with one or more unsaturated fatty acid tails
Phospholipid
Lipid with two (hydrophobic) fatty acid tails and a (hydrophilic) head that contains a phosphate group. Main constituent of eukaryotic cell membranes
Lipid Bilayer
double layer of phospholipids arranged tail-to-tail; structural foundation of all cell membranes
Steroids
a type of lipid with four carbon rings and no fatty acid tails
Wax
firm, water-repellent substance that is a complex, varying mixture of lipids
Protein
organic molecule that consists of one or more amino acid chains folded into a specific shape
Amino Acid
small organic compound that is a monomer of proteins. Consists of a carboxyl group, and amine group, and one of 20 R groups, all bonded to the same carbon atom
Peptide Bond
a covalent bond between the amine group of one amino acid and the carboxyl group of another. Joins amino acids in peptide and polypep-tide chains
Denaturation
loss of a protein’s three-dimensional shape
Prion
infectious protein
Nucleotide
small organic molecule with a deoxyri-bose or ribose sugar, a nitrogen-containing base, and one, two, or three phosphate groups; e.g., adenine, guanine, cytosine, thymine, uracil
ATP
Nucleotide that consists of an adenine base, a ribose sugar, and three phosphate groups. Nucleotide monomer of RNA and a coenzyme in many reactions. Important energy carrier in cells.
Nucleic Acids
molecule that consists of one or more strands of nucleotides; DNA or RNA
RNA
Nucleic acid that consists of ribose-containing nucleotides; most types are single-stranded
Plasma Membrane
membrane that encloses a cell and separates it from the external environment
Cytosol
jellylike mixture of water and solutes enclosed by a cell’s plasma membrane
Organelles
structure that carries out a specialized function inside the cell
Ribosomes
organelle of protein synthesis. An intact ribosome has two subunits each composed of rRNA and proteins
Cytoplasm
in a eukaryotic cell, collective term for everything between the cell’s plasma membrane and its nucleus. In a prokaryotic cell, everything enclosed by the plasma membrane.
Surface-to-Volume Ratio
a relationship in which the volume of an object increases with the cube of the diameter, and the surface area increases with the square. Limits cell size.
Adhesion Proteins
plasma membrane protein that helps cells stick together in animal tissues. Some types form adhering junctions and tight junctions.
Receptor Proteins
membrane protein that triggers a change in cell activity in response to a stimulus such as a hormone binding to it
Transport Proteins
membrane protein that passively or actively helps specific ions or molecules move across the membrane
Cell Wall
rigid, permeable layer of extracellular matrix that surrounds the plasma membrane of some cells
Pilus
protein filament that projects the surface of some prokaryotic cells
Flagella
long, slender cellular structure used for movement
Biofilm
community of microorganisms living within a shared mass of secreted slime
Nuclear Envelope
a double membrane that constitutes the other boundary of the nucleus. Nuclear pores in the membrane control the entry and exit of large molecules
Mitochondira
double-membraned organelle that produces ATP by aerobic respiration in eukaryotes
Chloroplasts
organelle of photosynthesis in the cells of plants and photosynthetic protists. Outer membranes enclose stroma and a highly folded thylakoid membrane
Vesicles
saclike organelle that stores, transports, or breaks down its contents
Lysosome
enzyme-filled vesicle that breaks down particles such as cellular debris
Endoplasmic Reticulum (ER)
membrane-enclosed organelle that consists of a continuous system of sacs and tubes extending from the nuclear envelope. Rough ER makes and modifies proteins; smooth ER makes phospholipids, stores calcium, and has additional functions in some cells
Golgi Body
organelle that modifies polypeptides and lipids, then sorts and packages the finished products into vesicles
