Basic Definition Part1

Agrobacterium tumefaciens
The bacterium which causes crown gall of dicot plants. It inserts its own Ti plasmid DNA into the host plant DNA. The inserted DNA produces growth hormones which result in the tumor and provides a habitat for the bacteria. This is an example of natural genetic engineering. The Ti plasmid can be used as a transformation vector.

amino acid
The molecular building blocks for proteins.

antisense DNA
DNA strand that is complementary (opposite) to the functional gene. Antisense DNA can block the function of the normal sense DNA. This method was used in the construction of the Flavr Savr tomato.

band
In gels and blots, bands are visible indications of a particular fragment of a certain size. There may be one to many bands per lane.

base pair
In DNA, there are four possible bases: cytosine (C), guanine (G), adenine (A), and thymine (T). Cytosine and thymine are pyrimidine bases; adenine and guanine are purine bases. Cytosine is complementary to guanine while adenine is complementary to thymine. If one strand of DNA has the sequence ATTGC then the complementary strand will be TAACG. Two complementary bases constitute a base pair. In RNA, thymine is replaced by uracil.

biotechnology
Broad sense: Technology for working with biological systems. Includes genetic engineering, human and veterinary medicine, crop and animal breeding, diagnostics, pharmaceuticals, forensics, etc. Narrow sense: Genetic engineering.

blot, northern
A pattern of RNA fragments transferred to a nitrocellulose membrane from a gel. The gel has undergone electrophoresis to separate fragments according to size. The RNA fragments are arranged in different lanes for each sample. Each lane contains bands which are fragments of different sizes. Radioactive probes are often used to visualized particular bands by autoradiography.

blot, southern
A pattern of DNA fragments transferred to a nitrocellulose membrane from a gel. The gel has undergone electrophoresis to separate fragments according to size. The DNA fragments are arranged in different lanes for each sample. Each lane contains bands which are fragments of different sizes. Radioactive probes are often used to visualized particular bands by autoradiography.

blot, western
A pattern of proteins transferred to a nitrocellulose membrane from a gel. The gel has undergone electrophoresis to separate fragments according to size. The proteins are arranged in different lanes for each sample. Each lane contains bands which are fragments of different sizes. Labeled antibody probes are often used to visualize particular bands.

Bt (Bacillus thuringiensis)
A soil bacterium that produces insecticidal proteins. There are several different kinds of proteins produced by different strains of Bt. Some are effective against larvae of moths and butterflies. Others are effective against larvae of beetles. The Bt protein has been introduced into various crops as a built-in insecticide.

chromosome
A linear structure in the nucleus of plants and animals that is visible in light microscopy when stained. The chromosome is a single, long, linear molecule of DNA and associated proteins. Bacteria have a single circular chromosome; other organisms may have many linear chromosomes.

clone
Def. 1. Noun: An exact duplicate of a fragment of DNA Def. 2. Noun: An exact duplicate of entire organism. Def. 3. Verb: to make a clone

cloning vector
A DNA molecule capable of autonomous replication within the cloning host cell (e.g E. coli). The vectors contain restriction enzyme sites for insertion of foreign DNA. Cloning vectors are derived from bacterial plasmids, bacteriophages, or viruses.

codon
Set of three nucleotides that specify a particular amino acid during protein synthesis.

DNA
Deoxyribonucleic acid, the molecule that stores genetic information. Composed of two complementary strands. See base pairs.

cDNA
Complementary DNA to a particular RNA fragment.

rDNA
Def. 1. Ribosomal DNA; DNA which codes for ribosomesDef. 2. Recombinant DNA (see next item)

DNA, recombinant
DNA that has been cut and spliced back together in a new sequence. The DNA may be from one organism or from more than one organism

DNA, repetitive
Fragments of DNA that appear in multiple copies in a single individual.

E. coli (Escherichia coli)
A common intestinal bacterium that is widely used in genetic engineering as a host for a cloning vector. Some strains of E. coli are important foodborne pathogens. Lab strains are of the harmless variety.

electroporation
Transformation technique that uses electric fields to temporarily increase permeability of cells to foreign DNA.

event
An "event" in genetic engineering is the insertion of a particular piece of foreign DNA into the chromosome of the recipient. Insertion occurs in random locations, so each event is unique. The event can affect how a gene is expressed in the organism. Once an event occurs, the transgene can be passed to the next generation as a normally inherited gene.

fingerprint
A set of molecular markers sufficiently diverse to identify particular individuals with reasonable certainty.

gel, agarose
A substance used to separate DNA or RNA fragments by size. Used for southern and northern blots.

gel, polyacrylamide
A substance used to separate proteins by size. Used for western blots.

gene
The basic unit of inheritance. A segment of DNA that codes for a particular protein.

gene gun
Transformation technique that uses accelerated particles coated with DNA to introduce foreign DNA into recipient plant.

gene therapy
The introduction of new genes into individuals to cure diseases or genetic abnormalities.

genetic code
The genetic information in DNA is encoded with four different nucleotide bases: A, C, G, and T (see base pair). A set of three consecutive nucleotide bases constitutes a codon. A codon specifies a particular amino acid that is added during synthesis of a protein.

genetic engineering
The process of modifying organisms to obtain desired traits by incorporating recombinant DNA from native, alien, or synthetic sources. The term is usually reserved for in vitro recombinant DNA techniques.

genome
The full chromosome set containing all the genes of a particular individual.

genomics
The study of the structure and function of genomes. Genomics usually involves high speed sequencing of the DNA and computer searches for sequences that code for genes.

genotype
The sum total of the genetic information of an organism including the linkage relationships between genes. The genotype, modified by environment, determines the phenotype.

GMO
Genetically modified organism. An organism that has incorporated a functional foreign gene through recombinant DNA technology. The novel gene exists in all of its cells and is passed through to progeny. Same as transgenic.

hybridization, nucleic acid
Complementary strands of DNA or RNA will spontaneously match up with each other and bond together under the right conditions. This is called nucleic acid hybridization and is used when probing southern and northern blots.

integration event
See event.

Kb (kilobase)
The number of base pairs (in thousands) that denote the size of a nucleic acid fragment.

lane
On a gel or a blot, a lane belongs to one sample. It contains fragments of different sizes that were separated by gel electrophoresis. See band, blot.

library, DNA
A large set of clones of DNA fragments from a particular organism. DNA libraries are usually maintained in E. coli or in bacteriophages.

ligation
Joining two fragments of DNA end to end. See sticky ends.

linkage
Measures the physical distance between two genes. Genes that are close together are unlikely to segregate in a sexual cross. Distant genes segregate independently are are then said to be unlinked.

molecular markers
Genetic traits which are detectable on gels or blots and can be used to construct genetic maps. Molecular markers usually have no known function. RFLPs are molecular markers.

mutation
A spontaneous or induced genetic change in the DNA of an organism. Most mutations are undesirable, but a few are useful such as dwarfing genes in cereal crops that allow the plants to stand better.

nuclease
Any enzyme that cuts nucleic acids. See restriction enzyme.

nucleic acid
DNA or RNA

nucleotide
Building block of DNA or RNA. See base pair.

nucleus
A cellular organelle in plants and animals that contains the chromosomes which in turn are composed of DNA plus protein.

particle bombardment
Using metal particles to blast DNA into cells for the purpose of genetic engineering. A gene gun is used to propel the metal particles.

PCR
Polymerase chain reaction. An amazingly sensitive technique that allows the specific amplification of extremely small amounts of particular DNA fragments using DNA polymerase and specific primers.

phenotype
The observable characters of an organism due to genetic and environmental effects on development. See genotype.

plasmid
A small circular piece of DNA in bacteria that resembles the bacterial circular chromosome, but is dispensable. Some bacterial strains contain many plasmids and some contain none. Plasmids are often used in genetic engineering as cloning vectors.

polymerase
Any enzyme that adds subunits to chains of macromolecules. Example is DNA polymerase.

primer
A small segment of DNA which binds to a complementary strand of DNA. Primers are necessary to start the DNA polymerase enzyme and therefore are necessary in PCR.

probe
A fragment of DNA, usually labeled with radioactive 32P, that detects homologous sequences on southern blots.

promoter
A segment of DNA near the beginning of a gene that controls if and when the gene is actually expressed. Promoters can be specific for certain tissues such as roots, seeds, etc.

protein
Molecules composed of amino acids. Proteins constitute the enzymes and many of the structural components of cells.

protease
An enzyme that cleaves proteins.

proteomics
The study of the structure and function of proteins.

purine and pyrimidine
See base pair.

recombinant
Def. 1. In classical genetics, an organism containing a combination of alleles different from either parentDef. 2. In molecular genetics, a DNA molecule containing a novel sequence. See rDNA.

restriction enzyme
A class of enzymes that cut DNA at specific sequences called restriction sites. Restriction enzymes were key to making genetic engineering possible. See RFLP.

RFLP
Restriction fragment length polymorphism. RFLPs are generated by digesting DNA with restriction enzymes. The DNA is separated by size by gel electrophoresis. Slight differences in homologous fragments may exist between individuals. These length polymorphisms are RFLPs. See blot.

ribosome
Cellular organelle that performs protein synthesis.

RNA
Ribonucleic acid. The three basic types are messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).

Roundup Ready
A trademark for plants that are genetically engineered to be resistant to the herbicide Roundup (technical name: glyphosate).

sequence
Noun: the particular order of nucleotides in a DNA or RNA fragment. Verb: to determine the particular order of nucleotides in a strand of DNA.

sticky ends
After cutting with restriction enzymes, the ends of DNA fragments are "sticky". They can easily be joined with other fragments that were cut with the same enzyme and so have complementary sticky ends.

transcription
The copying of genetic information from DNA to messenger RNA (mRNA).

transformation
The process of incorporating foreign DNA into an organism.

transgene
A foreign gene incorporated by transformation.

transgenic
An organism that has incorporated a functional foreign gene through recombinant DNA technology. The novel gene exists in all of its cells and is passed through to progeny. Same as genetically modified organism (GMO).

translation
Protein synthesis. The conversion of information from mRNA into a protein