AP Biology

Organic Chemistry

The study of carbon compounds (organic compounds)

Valence

The bonding capacity of a given atom; the number of covalent bonds that an atom can form, which usually equals the number of unpaired electrons in its outermost (valence) shell

Hydrocarbon

An organic molecule consisting only of carbon and hydrogen

Isomer

One of two or more compounds that have the same numbers of atoms of the same elements but different structures and hence different properties

Structural Isomers

One of two or more compounds that have the same molecular formula but differ in the covalent arrangements of their atoms

Cis-trans Isomer

One of several compounds that have the same molecular formula and covalent bonds between atoms but differ in the spatial arrangements of their atoms owing to the inflexibility of double bonds; formerly called a geometric isomer

Enantiomer

One of two compounds that are mirror images of each other and that differ in shape due to the pressure of an asymmetric carbon

Functional Group

A specific configuration of atoms commonly attached to the carbon skeletons of organic molecules and involved in chemical reactions

Adenosine Triphosphate (ATP)

An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells

Macromolecules

A giant molecule formed by joining of smaller molecules, usually by a dehydration reaction. Polysaccharides, proteins, and nucleic acids are macromolecules

Polymer

A long molecule consisting of many similar or identical monomers linked together by covalent bonds

Monomers

The subunit that serves as the building block of a polymer

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

Hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water; functions in the disassembly of polymers to monomers

Carbohydrates

A sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides)

Monosaccharides

The simplest carbohydrates, 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 CH2O

Disaccharide

A double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction

Glycosidic Linkage

A covalent bond formed between two monosaccharides by a dehydration reaction

Polysaccharides

A polymer of many monosaccharides, formed by dehydration reactions

Starch

A storage polysaccharide in plants, consisting entirely of glucose monomers joined by glycosidic linkages

Glycogen

An extensively branched glucose storage polysaccharide found in the liver and muscle of animals; the animal equivalent of starch

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

Lipid

Any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water

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

Triacylglycerol

A lipid consisting of three fatty acids linked to one glycerol molecule; also called a fat or triglyceride

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

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

Trans Fat

An unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds

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

Steroids

A type of lipid characterized by a carbon skeleton consisting of four fused rings various chemical groups attached

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

Catalysts

A chemical agent that selectively increases the rate of a reaction without being consumed by the reaction

Polypeptide

A polymer of many amino acids linked together by peptide bonds

Protein

A biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure

Amino Acid

An organic molecule possessing both a carboxyl and an amino group. Amino acids serve as the monomers of polypeptides

Peptide Bond

The covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction

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

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

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

Gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)

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

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

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

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

Polynucleotide

A polymer consisting of many nucleotide monomers in a chain. The nucleotides can be those of DNA or 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

Pyrimidine

One of two types of nitrogenous bases found in nucleotides, characterized by a six-membered ring. Cytosine (C), thymine (T), and uracil (U) and pyrimidines

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

Deoxyribose

The sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose, the sugar component of RNA nucleotides

Ribose

The sugar component of RNA nucleotides

double helix

The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.

Antiparallel

referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5'S3' directions).

Bioinformatics

The use of computers, software, and mathematical models to process and integrate biological information from large data sets

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

Proteomics

The systematic study of sets of proteins and their properties, including their abundance, chemical modifications, and interactions