G

G- Proteins:

These are guanine nucleotide binding trimeric proteins that reside in the plasma menbrane.

G Banding:

It is a technique that generates a striated pattern in metaphase chromosomes that distinguishes the member of a hapoid set.

gDNA:

genomic DNA.

Gamete:

Mature male or female reproductive cell (sperm or ovum) with a haploid set of chromosomes (23 for humans).

Gel Shift Assay:

(gel mobility shift assay, band shift assay) A method by which one can determine whether a particular protein preparation contains factors which bind to a particular DNA fragment.

Gene:

The fundamental physical and functional unit of heredity. A gene is an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product (i.e., a protein or RNA molecule) that contributes to or influences the phenotype of the cell. A gene usually contains coding regions, introns, untranslated regions and control regions.

Gene Cluster:

It is a group of adjacent genes that are related or identical.

Gene Conversion:

The alteration of all or part of a gene by a homologous donor DNA that is itself not altered in the process.

Gene Expression:

The process by which information coded by genes is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mRNA and then translated into protein and those that are transcribed into RNA but not translated into protein.

Gene Families:

Groups of closely related genes that make similar products.

Gene Product:

The biochemical material, either RNA or protein, resulting from expression of a gene. The amount of gene product is used to measure how active a gene is; abnormal amounts can be correlated with disease- causing alleles.

Gene Superfamily:

A large group of genes related by sequence homologies or by the structures of their products, and by their involvement in different aspects of the same larger process.

Gene Therapy:

A technique involving the use of foreign genetic material to correct a genetic defect or to modify the phenotype of an affected individual, by targeting the somatic cells.

Genetic Code:

The sequence of nucleotides, coded in triplets (codons) along the mRNA, that determines the sequence of amino acids in protein synthesis. The DNA sequence of a gene can be used to predict the mRNA sequence, and the genetic code can in turn be used to predict the amino acid sequence.

Genetic Disease:

Heritable genetic alterations from wild type which, when expressed, result in decreased viability of the individual receiving the altered gene(s).

Genetic Map:

The ordering of genes by the statistical determination of recombination events between them. Genes separated by greater distances are more likely to recombine.

Genetics:

The study of the patterns of inheritance of specific traits.

Genome:

The entire compliment of genetic material in the form of permanently maintained DNA for a given organism. Its size is generally given as its total number of base pairs. Also present in the genome are structural segments such as telomeric and centromeric DNAs and replication origins, and intergenic DNA.

Genome Projects:

Research and technology development efforts aimed at mapping and sequencing some or all of the genome of human beings and other organisms.

Genomic Blot:

A type of Southern blot specifically used to analyze a mixture of DNA fragments derived from total genomic DNA. Because genomic DNA is very complicated, when it has been digested with restriction enzymes, it produces a complex set of fragments ranging from tens of bp to tens of thousands of bp. However, any specific gene will be reproducibly found on only one or a few specific fragments. A million identical cells will produce a million identical restriction fragments for any given gene, so probing a genomic Southern with a gene-specific probe will produce a pattern of perhaps one or just a few bands.

Genomic Clone:

A piece of DNA taken from the genome of a cell or animal, and spliced into a bacteriophage or other cloning vector. A genomic clone may contain coding regions, exons, introns, 5' flanking regions, 5' untranslated regions, 3' flanking regions, 3' untranslated regions, or it may contain none of these...it may only contain intergenic DNA.

Genomic Library:

A collection of clones made from a set of randomly generated overlapping DNA fragments representing the entire genome of an organism. Compare library, arrayed library.

Genotype:

The set of genes that an individual carries; usually refers to the particular pair of alleles (alternative forms of a gene) that a person has at a given region of the genome.

Germline:

Tissues involved in the generation of haploid gametes.

Glycosylation:

The covalent addition of sugar moities to N or O atoms present in the side chains of certain amino acids of certain proteins, generally occuring within the Golgi apparatus during secretion of a protein.

GRE:

Glucocorticoid Response Element: A binding site in a promoter to which the activated glucocorticoid receptor can bind. The glucocorticoid receptor is essentially a transcription factor which is activated only in the presence of glucocorticoids. The activated receptor will bind to a GRE, and transcription of the adjacent gene will be altered.

Guanine (G):

A nitrogenous base found in DNA and RNA, one member of the base pair G- C (guanine and cytosine). (2-amino-6-hydroxypurine).

Gyrase:

An enzymatic activity responsible for maintaining supercoiling in DNA.