Chapter 5: The Structure and Function of Large Biological Molecules

37803936	macromolecules	giant molecules formed by the joining of smaller molecules, usually by a condensation reaction; polysaccharides, proteins, and nucleic acids are considered these
37803937	polymer	a long molecule consisting of many similar or identical building blocks linked by covalent bonds, much as a train consists of a train of cars; carbohydrates, nucleic acids, and proteins are examples of these
37803938	monomers	repeating units that serve as building blocks of a polymer; smaller molecules; some also have functions on their own
37803939	condensation reaction	when two monomers connect to each other by a reaction in which two molecules are covalently bonded to each other through a loss of a molecule
37803940	dehydration reaction	when two monomers connect to each other by a reaction in which a hydroxyl group covalently bonds to a hydrogen atom, which causes the loss of a water molecule in the process
37803941	enzymes	specialized macromolecules that speed up chemical reactions in cells; considered proteins
37803942	hydrolysis	a process that occurs when the bonds between two monomers are broken by the addition of water molecules, with a hydrogen from the water attaching to one monomer and a hydroxyl group attaching to the adjacent monomer
37803943	carbohydrates	a sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides)
37803944	monosaccharides	molecules with a general formula of some multiple of the unit CH2O; these are major nutrients as carbon skeletons serve as raw material for synthesis of other organic molecules
37803945	disaccharide	molecule that consists of two monosaccharides joined by a glycosidic linkage
37803946	glycosidic linkage	a covalent bond formed between two monosaccharides by a dehydration reaction; the most common type of this in nature is a "1-4"
37803947	polysaccharides	macromolecules; polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages; serve as storage material, hydrolyzed as needed to provide sugar for cells; building material for structures that protect a cell or an organism; architecture and function are determined by sugar monomers and by positions of glycosidic linkages
37803948	starch	a polymer of glucose monomers; synthesizing this allows for the storage of glucose, and thus, stored energy; this molecule is helical in shapeq
37803949	glycogen	a polymer of glucose that is like amylopectin (a complex starch that is a branched polymer with 1-6 linkages at branch points) but more extensively branched; animals store this
37803950	cellulose	a polysaccharide that is a major component of the tough walls that enclose plant cells; most abundant organic compound on Earth; polymer of glucose
37803951	chitin	an important structural polysaccharide used by arthropods to build their exoskeletons; pure forms of this are leathery and flexible, but they harden when encased within calcium carbonate
37803952	lipid	one of a group of compounds, including fats, phospholipids, and steroids, that mix poorly, if at all, with water; they are not composed of true polymers, so they are generally not large enough to be considered macromolecules; they are hydrophobic because they contain few polar bonds and many hydrocarbon regions; they vary in form and function
37803953	fat	a large molecule constructed by two smaller molecules, glycerol and a fatty acid, through dehydration reaction; major function is energy storage
37803954	glycerol	an alcohol with three carbons, each having a hydroxyl group
37803955	fatty acid	a molecule with a long carbon skeleton (usually 16 or 18 in length) and a carboxyl group at the end of the molecule (hence the acid); these are hydrophobic
37803956	triacylglycerol	a fat that consists of three fatty acids linked to one glycerol molecule; linkages that bond hydroxyl to carboxyl are called ester linkages
37803957	saturated fatty acid	a fatty acid that has no double-bonded carbon atoms so that as many hydrogen atoms as possible are bonded to the carbon skeleton
37803958	unsaturated fatty acid	a fatty acid that has one or more double-bonded carbon atoms formed by the removal of hydrogen atoms from the carbon skeleton; there will be a kink in the hydrocarbon chain wherever a -cis double-bond occurs (causes bending)
37803959	saturated fat	a fat made from saturated fatty acid; animal fats are solid at room temperature because they lack double-bonds, thus flexibility enables molecules to pack together tightly
37803960	unsaturated fat	a fat made from unsaturated fatty acids; they are liquid at room temperature (oils) because kinks in -cis bonding prevent molecules from packing together to solidify
37803961	trans fat	the fat that results when unsaturated fats are synthetically converted to saturated fats to prevent the separation of lipids (margarine and peanut butter are examples); this process produces saturated fats and unsaturated fats with trans double bonds
37803962	phospholipids	cells need these in order to exist because they make up cell membranes; has 2 fatty acids attached to glycerol instead of traditional 3 (triacylglycerol); always assemble into a double-layer aggregate because of hydrophilic head and hydrophobic tail
37803963	steroids	lipids characterized by a carbon skeleton consisting of four fused rings
37803964	cholesterol	a common component of animal cell membranes, and a foundation from which other steroids are synthesized; crucial molecule in animals, but can be dangerous when in high amounts
37803965	catalysts	chemical agents that selectively speed up chemical reactions without being consumed by the reaction; can be seen as workhorses that keep cells running by carrying out processes of life
37803966	polypeptides	polymers of all amino acids
37803967	proteins	macromolecules that are constructed from one or more polypeptides, each folded and coiled into a specific three-dimensional structure; all made from same 20 amino acids; most structurally sophisticated molecule known
37803968	amino acids	organic molecules possessing both carboxyl and amino groups
37803969	peptide bond	a covalent bond that results when two amino acids join through dehydration reaction
37803970	enzymatic	the type of protein that selectively accelerates chemical reactions; example: digestive enzymes release polymers in food
37803971	structural	the type of protein that supports an organism; example: insects and spiders use silk fibers for cocoons and webs, collagen and elastin provide fibrous framework in animal connective tissues; keratin is protein of hair, horns, feathers, etc.
37803972	storage	the type of protein that stores amino acids; example: ovalbumin is the protein of egg white, used as an amino acid source for developing embryos
37803973	transport	the type of protein that transports other substances; example: hemoglobin, the iron-containing protein of vertebrate blood, transports oxygen from lungs to other parts of the body
37803974	hormonal	the type of protein that coordinates an organism's activities; example: insulin, a hormone secreted by the pancreas, helps regulate the concentration of sugar in the blood of vertebrates
37803975	receptor	the type of protein that helps a cell respond to chemical stimuli; example: receptors built into the membrane of a nerve cell detect chemical signals released by other nerve cells
37803976	contractile and motor	the type of protein that controls movement; example: actin and myosin are responsible for the contraction of muscles; other proteins are responsible for the undulations of cilia and flagella
37803977	defensive	the type of protein that protects against disease; example: antibodies combat bacteria and viruses
38719356	globular	the shape of proteins that are roughly spherical
38719357	fibrous	the shape of proteins that are long and fiber-like
38719358	primary structure	the unique structure of amino acids; example: a polypeptide composed of 127 amino acids has 20^127 different ways it can be organized
38719359	secondary structure	the collection of coils and folds that result from hydrogen bonds between repeating constituents of the polypeptide backbone (not the amino acid sides)
38719360	alpha helix	a secondary structure that is a delicate coil held together by hydrogen bonding between every fourth amino acid
38719361	beta pleated sheet	a secondary structure in which two or more regions of the polypeptide chain lying side by side are connected by hydrogen bonds between parts of two parallel polypeptide backbones; it makes up the core of globular proteins
38719362	tertiary structure	the overall shape of a polypeptide that results from interactions between side chains of various amino acids
38719363	hydrophobic interaction	an interaction that contributes to tertiary structure; as a polypeptide folds into functional shape, amino acids with hydrophobic side chains usually end up in clusters at the core of the protein, away from water
38719364	disulfide bridges	links that form where two cysteine monomers are brought together by folding of protein; covalent bonds reinforce structure
38719365	quaternary structure	the overall protein structure that results from the gathering of polypeptide subunits; some proteins consist of 2 or more polypeptide chains combined into one macromolecule
38719366	sickle-cell disease	an inherited blood disorder that is caused by a substitution of one amino acid (valine) for the normal amino acid (glutamic acid) at a particular position in the primary structure of hemoglobin, the protein that carries oxygen in red blood cells
38719367	denaturation	the unraveling and loss of a protein's native shape due to alterations of its environment, such as pH, salt concentration, and temperature; this causes a protein to become biologically inactive
38719368	chaperonins	protein molecules that assist in the proper folding of other proteins; they do not specify the final structure of a protein, instead they keep the new polypeptide separated from "bad influences" in the cytoplasmic environment while it folds
38719369	x-ray crystallography	the method used to determine 3-D structures of proteins; developed in 1959
38719370	gene	a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)
38719371	nucleic acid	a polymer (polynucleotide) consisting of many nucleotide monomers; serves as a blueprint for proteins, and through the actions of proteins, for all cellular activities; two types are DNA and RNA
38719372	deoxyribonucleic acid	a double-stranded, helical nucleic acid molecule consisting of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine, guanine, cytosine, and thymine; it is capable of replicating and determining the inherited structure of a cell's proteins
38719373	ribonucleic acid	a type of nucleic acid consisting of nucleotide monomers with a ribose sugar and nitrogenous bases adenine, cytosine, guanine, and uracil; usually single-stranded; functions in protein synthesis, gene regulation, and as the genome of some viruses
38719374	messenger RNA	a nucleic acid that directs the production of polypeptides; this is found in the cells' ribosomes
38719375	nucleotide	the monomer of nucleic acids that has three parts: 1) a nitrogenous base (A, C, G, T, U); 2) a give-carbon sugar (a pentose); 3) a phosphate group
38719376	pyrimidines	the family of smaller nitrogenous bases in which its members have six-membered rings of carbon and nitrogen atoms; members include cytosine (C), thymine (T), and uracil (U)
38719377	purines	the family of larger nitrogenous bases in which its members have a six-membered ring fused to a five-membered ring; members are adenine (A) and guanine (G)
38719378	ribose	the sugar connected to RNA; has one more oxygen atom than the other sugar associated with nucleicacids
38719379	deoxyribose	the sugar connected to DNA; has one less oxygen atom than the other sugar associated with nucleic acids
38719380	double helix	the shape that cellular DNA molecules take as a result of spiraling around an imaginary axis; this was proposed by James Watson and Francis Crick in 1953 at Cambridge University
38719381	antiparallel	the pattern that describes the formation of DNA; the two sugar-phosphate backbones run in opposite 5' >> 3' directions from each other, somewhat like a divided highway