Chapter 5 The Structure and Function of Large Biological Molecules Flashcards
amino acid
An organic molecule possessing both a carboxyl and an amino group. Amino acids serve as the monomers of polypeptides.
antiparallel
Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5′ S 3′ directions).
bioinformatics
The use of computers, software, and mathematical models to process and integrate biological information from large data sets.
carbohydrate
A sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides).
catalyst
A chemical agent that increases the rate of a reaction without being deformed in the reaction.
cellulose
A structural polysaccharide of plant cell walls, consisting of glucose monomers joined by b glycosidic linkages.
chitin
A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.
cholesterol
A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids, such as many hormones.
dehydration reaction
A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule.
denaturation
In proteins, a process in which a protein loses its native shape due to the disruption of weak chemical bonds and interactions, thereby becoming biologically inactive; in DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme (noncellular) conditions of pH, salt concentration, or temperature.
deoxyribonucleic acid (DNA)
A nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell’s proteins.
deoxyribose
The sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose, the sugar component of RNA nucleotides.
disaccharide
A double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction.
double helix
The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.
enzyme
A macromolecule serving as a catalyst, a chemical agent that increases the rate of a reaction without being consumed by the reaction. Most enzymes are proteins.
fat
A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride.
fatty acid
A carboxylic acid with a long carbon chain. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form a fat molecule, also called triacylglycerol or triglyceride.
gene
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).
gene expression
The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.
genomics
The systematic study of whole sets of genes (or other DNA) and their interactions within a species, as well as genome comparisons between species.
glycogen
An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch.
glycosidic linkage
A covalent bond formed between two monosaccharides by a dehydration reaction.
hydrolysis
A chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers.
lipid
Any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water.
macromolecule
A giant molecule formed by the joining of smaller molecules, usually by a dehydration reaction. Polysaccharides, proteins, and nucleic acids are macromolecules.
monomer
The subunit that serves as the building block of a polymer.
monosaccharide
The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides. Also called simple sugars, monosaccharides have molecular formulas that are generally some multiple of CH 2 O .
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. The two types are DNA and RNA.
nucleotide
The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one to three phosphate groups.
peptide bond
The covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction.
phospholipid
A lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes.
polymer
A long molecule consisting of many similar or identical monomers linked together by covalent bonds.
polynucleotide
A polymer consisting of many nucleotide monomers in a chain. The nucleotides can be those of DNA or RNA.
polypeptide
A polymer of many amino acids linked together by peptide bonds.
polysaccharide
A polymer of many monosaccharides, formed by dehydration reactions.
protein
A biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure.
proteomics
The systematic study of sets of proteins and their properties, including their abundance, chemical modifications, and interactions.
purine
One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring fused to a five-membered ring. Adenine (A) and guanine (G) are purines.
pyrimidine
One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring. Cytosine (C), thymine (T), and uracil (U) are pyrimidines.
ribonucleic acid (RNA)
A type of nucleic acid consisting of a polynucleotide made up of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis, in gene regulation, and as the genome of some viruses.
ribose
The sugar component of RNA nucleotides.
saturated fatty acid
A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximizing the number of hydrogen atoms that are attached to the carbon skeleton.
sickle-cell disease
A recessively inherited human blood disorder in which a single nucleotide change in the a-globin gene causes hemoglobin to aggregate, changing red blood cell shape and causing multiple symptoms in afflicted individuals.
starch
A storage polysaccharide in plants, consisting entirely of glucose monomers joined by glycosidic linkages.
steroid
A type of lipid characterized by a carbon skeleton consisting of four fused rings with various chemical groups attached.
trans fat
An unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds.
triacylglycerol
A lipid consisting of three fatty acids linked to one glycerol molecule; also called a fat or triglyceride.
unsaturated fatty acid
A fatty acid that has one or more double bonds between carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen atoms attached to the carbon skeleton.
X-ray crystallography
A technique used to study the three-dimensional structure of molecules. It depends on the diffraction of an X-ray beam by the individual atoms of a crystallized molecule.
