Section of DNA.
Many of the genes are inactive and never do anything. Other genes only produce mRNA at certain points in the life of a cell or in response to certain conditions. The production of mRNA is known as gene expression. Genes that do not produce mRNA and do not contribute to the phenotype are not being expressed. Gene therapy is when DNA is introduced into a patient to treat a genetic disease. The new DNA usually contains a functioning gene to correct the effects of a disease-causing mutation. 1  Gene therapy uses sections of DNA (usually genes) to treat or prevent disease. 2  The DNA is carefully selected to correct the effect of a mutated gene that is causing disease. 1 A section of DNA/gene containing instructions for making a useful protein is packaged within a vector, usually a virus, bacterium or plasmid. 2  The vector acts as a vehicle to carry the new DNA into the cells of a patient with 1 Gene therapy uses sections of DNA (usually genes) to treat or prevent disease. 2  The DNA is carefully selected to correct the effect of a mutated gene that is causing disease. 3  The technique was first developed in 1972 but has, so far, had limited success in treating human diseases. 1 A section of DNA/gene containing instructions for making a useful protein is packaged within a vector, usually a virus, bacterium or plasmid. 2  The vector acts as a vehicle to carry the new DNA into the cells of a patient with a genetic disease. It is important to note that genes themselves do not cause disease—genetic disorders are caused by mutations that make a gene function improperly. For example, when people say that someone has “the cystic fibrosis gene,” they are usually referring to a mutated version of the CFTR gene, which causes the disease. A condition caused by mutations in one or more genes is called a genetic disorder. In some cases, gene mutations are so severe that they prevent an embryo from surviving until birth. These changes occur in genes that are essential for development, and often disrupt the development of an embryo in its earliest stages. Only a fraction of the genes in a cell are expressed at any one time. The variety of gene expression profiles characteristic of different cell types arise because these cells have distinct sets of transcription regulators. Some of these regulators work to increase transcription, whereas others prevent or suppress it. Given this statistic, it is not surprising that the primary control point for gene expression is usually at the very beginning of the protein production process — the initiation of transcription. A gene is a segment of DNA that encodes function. A chromosome consists of a long strand of DNA containing many genes. A human chromosome can have up to 500 million base pairs of DNA with thousands of genes. These alleles encode slightly different versions of a protein, which cause different phenotype traits. Colloquial usage of the term having a gene (e.g., good genes, hair colour gene) typically refers to having a different allele of the gene. There are many ways that gene expression is controlled in eukaryotes, but methylation of DNA (not to be confused with histone methylation) is a common epigenetic signaling tool that cells use to lock genes in the off position.  Only one of the Y chromosome genes, the SRY gene, is responsible for male anatomical traits. When any of the 9 genes involved in sperm production are missing or defective the result is usually very low sperm counts and subsequent infertility. This is due to the fact that men only have one X chromosome. Subsequently, genes on that chromosome not coding for gender are usually expressed in the male phenotype even if they are recessive since there are no corresponding genes on the Y chromosome in most cases. 1 Genetic testing for all of the currently known FALS genes costs about $6,000. 2  Genetic testing for one gene usually costs $1,500-2,000. 3  When the genetic mutation in a family is already known, the cost to test for the familial mutation is usually around $400. 1 Genetic testing for one gene usually costs $1,500-2,000. 2  When the genetic mutation in a family is already known, the cost to test for the familial mutation is usually around $400. 3  Genetic testing is not always covered by insurance. 4  Check with your insurance company about any out of pocket expense prior to testing.
http://highered.mheducation.com/sites/9834092339/student_view0/chapter15/simple_gene_expression.html http://www.yourgenome.org/facts/what-is-gene-therapy http://www.yourgenome.org/facts/what-is-gene-therapy http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/mutationscausedisease http://www.nature.com/scitable/topicpage/gene-expression-14121669 https://en.wikipedia.org/wiki/Gene http://www.nature.com/scitable/topicpage/The-Role-of-Methylation-in-Gene-Expression-1070 http://anthro.palomar.edu/biobasis/bio_4.htm http://www.alsa.org/about-als/genetic-testing-for-als.html
A gene is usually __________.