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Biology 10-12

Molecular Biology The study of the molecular basis of genes and gene expression
Bacteriophage A virus that infects bacteria; also called a phage
Nucleotide A building block of nucleic acids, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one or more phosphate groups
Polynucleotide A polymer made up of many nucleotide monomers covalently bonded together
Sugar-Phosphate Backbone The alternating chain of sugar and phosphate to which nitrogenous bases are attached
Deoxyribonucleic Acid (DNA) A double-stranded helical nucleic acid molecule consisting of nucleotide monomers with deoxyribose sugar and the nitrogenous bases A, C, G, and T. It is capable of replicating and is an organism’s genetic material
Thymine A single-ring nitrogenous base found in DNA and RNA
Adenine A double-ring nitrogenous base found in DNA and RNA
Cytosine A single-ring nitrogenous base found in DNA and RNA
Guanine A double-ring nitrogenous base found in DNA and RNA
Uracil A single-ring nitrogenous base found in RNA
Double Helix The form of native DNA, referring to its two adjacent polynucleotide strands interwound into a spiral shape
Semiconservative Model Type of DNA replication in which the replicated double helix consists of one old strand and one newly made strand
DNA polymerase Adds nucleotides to a growing chain; proofreads and corrects improper base pairings
DNA ligase An enzyme that joins small fragments into a continuous chain
Transcription The synthesis of RNA on a DNA template
Translation The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule; change of “language” from nucleotides to amino acids
Triplet Code Set of three-nucleotide-long “words” that specify amino acids for polypeptide chains
Codon A three-nucleotide sequence in mRNA that specifies a particular amino acid or polypeptide termination signal; the basic unit of the genetic code
Genetic Code The set of rules that dictates the correspondence between RNA codons in an mRNA molecule and amino acids in protein
RNA Polymerase A large molecular complex that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template
Promoter A specific nucleotide sequence in DNA located near the start of a gene that is the binding site for RNA polymerase and the place where transcription begins
Terminator A special sequence of nucleotides in DNA that marks the end of a gene; signals RNA polymerase to release the newly made RNA molecule and then depart from the gene
Messenger RNA The type of ribonucleic acid that encodes genetic information from DNA and conveys it to ribosomes, where the information is translated into amino acid sequences
Intron Interrupting sequences that separate exons
Exon The coding region
RNA Splicing Removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence; occurs before mRNA leaves nucleus
Transfer RNA A type of ribonucleic acid that functions as an interpreter in translation. Each molecule has a specific anticodon, picks up a specific amino acid, and conveys the amino acid to the appropriate codon on mRNA
Anticodon On a tRNA molecule, a specific sequence of three nucleotides that is complementary to a codon triplet on mRNA
Ribosome A cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm.
Ribosomal RNA The type of ribonucleic acid that, together with proteins, makes up ribosomes; the most abundant type of RNA in most cells
Start Codon The specific three-nucleotide sequence (AUG) to which an initiator tRNA molecule binds, starting translation of genetic information
P Site This site holds the tRNA carrying the growing polypeptide chain
A Site This site holds the tRNA that carries the next amino acid in the polypeptide chain
E Site “Exit” site
Translocation During protein synthesis, the movement of a tRNA molecule carrying a growing polypeptide chain from the A site to the P site on a ribosome
Stop Codon In mRNA, one of three triplets (UAG, UAA, UGA) that signal gene translation
Mutation A change in the nucleotide sequence of an organism’s DNA; the ultimate source of genetic diversity
Gene Regulation The turning on and off of genes within a cell in response to environmental stimuli or other factors
Gene Expression The process whereby genetic information flows from genes to proteins; the flow of genetic information from the genotype to phenotype
Promoter A specific nucleotide sequence in DNA located near the start of a gene that is the binding site for RNA polymerase and the place where transcription begins
Operator a segment of DNA to which a transcription factor binds to regulate gene expression by repressing it.
Operon A unit of genetic regulation common in prokaryotes; a cluster of genes with related functions, along with the promoter and operator that control their transcription
Repressor A substance that acts on an operon to inhibit messenger RNA synthesis
Regulatory Gene A gene that codes for a protein, such as a repressor, that controls the transcription of another gene or group of genes
Lac Operon Inactivated when binded to lactose; active when lactose is not present
Trp Operon Activated when tryptophan is present; inactive when it is not
Activator A protein that switches on a gene or group of genes
Differentiation The specialization in the structure and function of cells that occurs during the development of an organism; results from selective activation and deactivation of the cells’ genes
Histone A small protein molecule associated with DNA and important in DNA packing in the eukaryotic chromosome
Nucleosome The bead-like unit of DNA packing in a eukaryotic cell; consists of DNA wound around a protein core made up of eight histone molecules
Epigenetic Inheritance The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence of a genome, such as the chemical modification of histone proteins or DNA bases
X Chromosome Inactivation The inactivation of one X chromosome in each somatic cell
Barr Body A deactivated X chromosome found in the nuclei of female mammalian cells
Transcription Factor A protein that functions in initiating or regulating transcription. It binds to DNA or to other proteins that bind to DNA
Enhancer A eukaryotic DNA sequence that helps stimulate the transcription of a gene at some distance from it
Silencer A eukaryotic DNA sequence that functions to inhibit the start of gene transcription
Alternative RNA Splicing A type of regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns
MicroRNA A small, single-stranded RNA molecule that associates with one or more proteins in a complex that can prevent translation of an mRNA with a complementary sequence
RNA Interference A biotechnology technique used to silence the expression of specific genes. Triggers the breakdown of the gene’s mRNA
Homeotic Gene A master control gene that determines the identity of a body structure of a developing organism, presumably by controlling the developmental fate of groups of cells
DNA Microarray Used to detect and measure the expression of thousands of genes at one time.
Signal Transduction Pathway A series of molecular changes that converts a signal on a target cell’s surface to a specific response inside the cell
Clone To produce genetically identical copies of a cell, organism, or DNA molecule; the collection of cells, organisms, or DNA molecules resulting from cloning
Regeneration The regrowth of body parts from pieces of an organism
Nuclear Transplantation A technique in which the nucleus of one cell is placed into another cell that already has a nucleus or in which the nucleus has been previously destroyed
Reproductive Cloning Using a somatic cell from a multicellular organism to make one or more genetically identical individuals
Embryonic Stem Cell Cell in the early animal embryo that differentiates during the development to give rise to all the different kinds of specialized cells in the body
Therapeutic Cloning The cloning of human cells by nuclear transplantation for therapeutic purposes, such as the generation of embryonic stem cells
Adult Stem Cell A cell present in adult tissues that generates replacements for nondividing differentiated cells. It is capable of differentiating into multiple cell types, but not all
Biotechnology The manipulation of living organisms or their components to make useful products
DNA Technology Methods used to study and/or manipulate DNA
Recombinant DNA A DNA molecule carrying nucleotide sequences derived from two or more sources
Genetic Engineering The direct manipulation of genes for practical purposes
Gene Cloning The production of multiple copies of a gene
DNA Ligase An enzyme that catalyzes the covalent bonding of adjacent DNA polynucleotide strands. It is used in genetic engineering to paste a specific piece of DNA
Restriction Site A specific sequence on a DNA strand that is recognized as a “cut site” by a restriction enzyme
Restriction Enzyme A bacterial enzyme that cuts up foreign DNA, thus protecting bacteria against intruding DNA from phages and other organisms.
Restriction Fragments Molecules of DNA produced from a longer DNA molecule cut up by a restriction enzyme. These are used in genome mapping and other applications
Genomic Library A set of DNA fragments representing an organism’s entire genome. Each segment is usually carried by a plasmid or phage
Reverse Transcriptase An enzyme used by retroviruses that catalyzes the synthesis of DNA on an RNA template
Complementary DNA A DNA molecule made in vitro using mRNA as a template & the enzyme reverse transcriptase. Corresponds to a gene but lacks the introns present in DNA of genome
Nucleic Acid Probe A radioactively or fluorescently labeled single-stranded nucleic acid molecule used to find a specific gene or other nucleotide sequence within a mass of DNA
Genetically Modified Organism An organism that has acquired one or more genes by artificial means. If the gene is from another species, the organism is also known as a transgenic organism
Transgenic Organism An organism that contains genes from another species
Ti Plasmid A bacterial plasmid that induces tumors in plant cells that the bacterium infects; stands for “tumor inducing”
Gene Therapy A treatment for a disease in which the patient’s defective gene is supplemented or altered
Forensics The scientific analysis of evidence for crime scene and other legal proceedings
DNA Profiling A procedure that analyzes DNA samples to determine if they came from the same individual
Polymerase Chain Reaction A technique used to obtain many copies of a DNA molecule or a specific part of a DNA molecule
Primer Short, artificially created, single-stranded DNA molecule that binds to each end of a target sequence during a PCR procedure
Gel Electrophoresis A technique for separating and purifying macromolecules, either DNAs or proteins. The molecules separate in the gel according to their rates of migration
Repetitive DNA Nucleotide sequences that are present in many copies in the DNA of a genome.
Short Tandem Repeat (STR) A series of short DNA sequences that are repeated many times in a row in the genome
STR Analysis Short tandem repeat analysis; a method of DNA profiling that compare the lengths of short tandem repeats selected from specific sites within the genome
Single Nucleotide Polymorphism (SNP) A one-nucleotide variation in DNA sequence found within the genomes of at least 1% of a population
Restriction Fragment Length Polymorphism Variation in the length of a restriction fragment. These are produced when homologous DNA sequences containing SNPs are cut up with restriction enzymes
Genomics The study of whole sets of genes and their interactions
Human Genome Project An international collaborative effort to map and sequence the DNA of the entire human genome
Transposable Elements “Jumping gene”; A segment of DNA that can move from one site to another within a cell and serve as an agent of genetic change
Whole-Genome Shotgun Method Method for determining the DNA sequence of an entire genome. After genome is cut into small fragments, each fragment is sequenced and then placed in the proper order
Proteomics The study of whole sets of proteins and their interactions
Created by: mapinero10