Gene, zygotic lethal

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Gene, zygotic lethal

Gene, zygotic lethal

A gene that is lethal (fatal) for the zygote, the cell formed by the union of a sperm (male sex cell) and an ovum (female sex cell). The zygote would normally develop into an embryo, as instructed by the genetic material within the unified cell. However, a zygotic lethal gene scotches prenatal development at its earliest point. A zygotic lethal gene is a mutated (changed) version of a normal gene essential to the survival of the zygote. The extent of the mutation can range from a change in a single base in the DNA to deletion (loss) of the entire gene.

RELATED TERMS
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Gene
1. A unit of DNA that carries information for the biosynthesis of a specific product in the cell. 2. Ultimate unit by which inheritable characteristics are transmitted to succeeding generations in all living organisms. Genes are contained by, and arranged along the length of, the chromosome. The gene is composed of deoxyribonucleic acid (DNA). Each chromosome of each species has a definite number and arrangement of genes, which govern both the structure and metabolic functions of the cells and thus of the entire organism.

Zygote
A fertilized egg. Or the diploid cell that results from the joining of two haploid gametes (sperm and egg) during sexual reproduction, that will cleave to form an embryo.

Cell
Fundamental structural unit of all life. The cell consists primarily of an outer plasma membrane, which separates it from the environment; the genetic material (DNA), which encodes heritable information for the maintainance of life; and the cytoplasm, a heterogeneous assemblage of ions, molecules, and fluid.

Sperm
A sperm cell, or spermatozoon (pl. spermatozoa) (in Greek: sperm = semen and zoon = alive), is the haploid cell that is the male gamete. It is carried in fluid called semen, and is capable of fertilising an egg cell to form a zygote. A zygote can grow into a new organism, such as a human. Sperm cells contain half of the genetic information needed to create life. Generally, the sex of the offspring is determined by the sperm, through the chromosomal pair "XX" (for a female) or "XY" (for a male).

Ovum
"Egg; the female reproductive element."

Embryo
The early stages of development before an organism becomes self supporting.

Genetic
Hereditary. Having to do with the genes.

Development
The process of growth and differentiation.

Essential
1. Something that cannot be done without. 2. Required in the diet, because the body cannot make it. As in an essential amino acid or an essential fatty acid. 3. Idiopathic. As in essential hypertension.

Mutation
A change in DNA that alters a gene and thus the gene's product, leading in some cases to deformity or disease. Mutations can occur spontaneously during cell division or can be triggered by environmental stresses, such as sunlight, radiation, and chemicals.

Base
A chemical compound that either donates hydroxide ions or absorbs hydrogen ions when dissolved in water. Bases and acids are referred to as opposites because the effect of an acid is to increase the hydronium ion concentration in water, whereas bases reduce this concentration. Arrhenius bases are water-soluble and always have a pH greater than 7 in solution.

Deletion
Loss of a segment of DNA from a chromosome (and hence from the genome).

SIMILAR TERMS
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Gene
1. A unit of DNA that carries information for the biosynthesis of a specific product in the cell. 2. Ultimate unit by which inheritable characteristics are transmitted to succeeding generations in all living organisms. Genes are contained by, and arranged along the length of, the chromosome. The gene is composed of deoxyribonucleic acid (DNA). Each chromosome of each species has a definite number and arrangement of genes, which govern both the structure and metabolic functions of the cells and thus of the entire organism.

Gene amplification
Making multiple copies of a gene. Repeated copying of a gene. Gene amplification plays a role in cancer cells. A tumor cell amplifies, or copies, DNA segments as a result of cell signals and sometimes environmental events. Amplification can occur in vivo (in the living individual) or in vitro (literally "in glass", or in a plastic vessel in the laboratory).

Gene array analysis
A way of analyzing the differential expression of thousands of species of mRNA (messenger RNA) at the same time in two different samples (as, for example, in normal vs. tumor tissue, or at different developmental stages). Gene array analysis involves synthesizing labeled cDNA (complementary DNA) from 2 or more sources, and hybridizing them to identical gene arrays. This procedure can be done in standard molecular biology laboratories with basic instrumentation.

Gene deletion
The total loss (or absence) of a gene. Gene deletion plays a role in birth defects and in the development of cancer.

Gene duplication
An extra copy of a gene. Gene duplication is a key mechanism in evolution. Once a gene is duplicated, the identical genes can undergo changes and diverge to create two different genes.

Gene expression
The process by which RNA and proteins are made from the instructions encoded in genes. Alterations in gene expression change the function of the cell, tissue, organ, or whole organism and sometimes result in observable characteristics associated with a particular gene.

Gene family
A group of genes related in structure and often in function. The genes belonging to a gene family are descended from an ancestral gene. For example, the hemoglobin genes of critical importance to red blood cells belong to one gene family created by gene duplication (making extra copies of a gene) and divergence (divergent changes in the copies of the gene).

Gene mapping
The process of determining the relative positions of genes on a chromosome (or another piece of DNA) and the distances between the genes in linkage units or in physical units.

Gene markers
Detectable genetic traits or distinctive segments of DNA that serve as landmarks for a target gene. Markers are on the same chromosome as the target gene. They must be near enough to the target gene to be genetically linked to it: to be inherited usually together with that gene, and so serve as signposts to it.

Gene pool
The sum total of genes, with all their variations, possessed by a particular species at a particular time.

Gene product
The RNA or protein that results from the expression of a gene. The amount of gene product is a measure of the degree of gene activity.

Gene silencing
A mechanism by which cells shut down large sections of chromosomal DNA. Gene silencing is done by incorporating the DNA to be silenced into a form of DNA called heterochromatin that is already silent. The process of gene silencing is important for the differentiation of many different types of cells.

Gene testing
Testing a sample of blood (or another fluid or tissue) for evidence of a gene. The evidence can be biochemical, chromosomal, or genetic. The aim is to learn whether a gene for a disease is present or absent.

Gene therapy
Using genes inserted into the patient's body or tumor to stimulate the immune system to fight cancer.

Gene Therapy
Gene therapy is correcting functional gene loss by delivering genes to human tissues. Often DNA viruses engineered to be safe or nonviral DNA are used to help deliver a healthy gene to the tissue cells.

Gene transfer
The insertion of unrelated genetic information in the form of DNA into cells. There are different reasons to do gene transfer. Perhaps foremost among these reasons is the treatment of diseases using gene transfer to supply patients with therapeutic genes. There are also different ways to transfer genes. Some of these methods involve the use of a vector such as a virus that has been specifically modified so it can take the gene along with it when it enters the cell.

Gene, candidate
Any gene thought likely to cause a disease. The gene may be a candidate because it is located in a particular chromosome region suspected of being involved in the disease or its protein product may suggest that it could be the disease gene in question.

Gene, evolutionarily conserved
A gene that has remained essentially unchanged throughout evolution. Conservation of a gene indicates that it is unique and essential. There is not an extra copy of that gene with which evolution can tinker. And changes in the gene are likely to be lethal.

Gene, marker
A detectable genetic trait or segment of DNA that can be identified and tracked. A marker gene can serve as a flag for another gene, sometimes called the target gene. A marker gene must be on the same chromosome as the target gene and near enough to it so that the two genes (the marker gene and the target gene) are genetically linked and are usually inherited together.

Gene, Med1 DNA repair
A gene that codes for one of the key enzymes involved in repairing DNA. The DNA in genes is constantly mutating and being repaired. This repair process is controlled by special genes. A mutation in a DNA repair gene such as Med1 can cripple the repair process and cause a cascade of unrepaired mutations in the genome that lead to cancer.

Gene, regulatory
A gene that regulates the expression of other genes. A regulatory gene is a nosy gene whose prime preoccupation is to horn in on other genes and control the rate at which they make products.

Gene, suicide
A gene whose expression in a cell is lethal for that cell. Suicide genes form the basis of a strategy for making cancer cells more vulnerable, more sensitive to chemotherapy. The approach has been to attach parts of genes expressed in cancer cells to other genes for enzymes not found in mammals that can convert a harmless substance into one that is toxic to the tumor.

Gene, transporter
A gene that allows drugs to enter cells or, in some cases, acts to keep them out. Transporter genes may account for discrepancies in the way drugs such as antidepressants, anticonvulsants, and chemotherapy agents work in different people. Also known as a drug-transporter gene.

Gene, Y-linked
A gene on the Y chromosome. Y-linkage is analogous to X-linkage (the presence of a gene on the X chromosome) in that it says a gene is on one of the sex chromosomes.

Gene-expression profiling
A genomic technique that based on the fact that only a fraction of the genes encoded in the genome of a cell are expressed by being transcribed into messenger RNA (mRNA). The complement of mRNAs in a cell largely dictates its complement of proteins. Consequently, gene expression is a major determinant of the biology of both normal and malignant cells.

General anesthesia
Controlled state of unconsciousness, accompanied by a partial or complete loss of pain sensation, protective reflexes, and the ability to respond purposefully to physical stimulation or verbal command.

General Hospital
General Hospital is a hospital in Portland, Oregon (USA).

General Hospital Kirchdorf
The General Hospital Kirchdorf is a hospital in Kirchdorf, Austria.

General Hospital Middelheim
The General Hospital Middelheim is a hospital in Antwerp, Belgium.

General Hospital Vienna
The General Hospital Vienna is a hospital in Vienna, Austria.

General Leonard Wood Army Community Hospital
The General Leonard Wood Army Community Hospital is a hospital in Fort Leonard Wood, Missouri, United States.

General paresis
Progressive dementia and generalized paralysis due to chronic inflammation of the covering and substance of the brain (meningoencephalitis). General paresis is a part of late (tertiary) syphilis, occurring a decade or more after the initial infection.

General practitioner
A physician who provides basic care. Unlike like a family physician, who must complete a three-year residency in obstetrics, pediatrics, internal medicine, and surgery, the general practitioner does not undergo specialized training after medical school.

General San Martin doctors
All doctors near General San Martin, Argentina. Doctors who can assist a patient in General San Martin.

General Santos doctors
All doctors near General Santos, the Philippines. Doctors who can assist a patient in General Santos.

General Security Hospital
The General Security Hospital is a hospital in Dammam, Saudi Arabia.

Generalisability, generalisation
The extent to which the findings of a clinical trial can be reliably extrapolated from the subjects who participated in the trial to a broader patient population and a broader range of clinical settings.

Generalized anxiety disorder
Abbreviated GAD. A condition characterized by 6 months or more of chronic, exaggerated worry and tension that is unfounded or much more severe than the normal anxiety most people experience. People with GAD usually expect the worst. They worry excessively about money, health, family, or work, even when there are no signs of trouble. They are unable to relax and often suffer from insomnia. Sometimes the source of the worry is hard to pinpoint. Simply the thought of getting through the day provokes anxiety. Many people with GAD also have physical symptoms, such as fatigue, trembling, muscle tension, headaches, irritability or hot flashes. People with GAD may feel lightheaded or out of breath. They also may feel nauseated or have to go to the bathroom frequently. Nearly 3% of the adult US population age 18 to 54 has GAD during the course of a given year. GAD most often strikes in childhood or adolescence, but can also begin in adulthood. It affects women more often than men, may run in families, and may also grow worse with stress. GAD often coexists with depression, substance abuse, and other anxiety disorders. Irritable bowel syndrome, often accompanies GAD. Treatment for GAD includes medications and cognitive-behavioral therapy.

Generalized vaccinia
Secondary lesions of the skin following vaccination which may occur in subjects with previously healthy skin but are more common in the case of traumatized skin, especially in the case of eczema (eczema vaccinatum). In the latter instance, generalized vaccinia may result from mere contact with a vaccinated person. Secondary vaccinial lesions may also occur following transfer of virus from the vaccination to another site by means of the fingers (autoinnoculation).

Generic
A drug not protected by a trademark. Also, the scientific name as opposed to the proprietary, brand name.

Generic drug
The term "generic" has several meanings as regards drugs: The chemical name of a drug. A term referring to the chemical makeup of a drug rather than to the advertised brand name under which the drug is sold. A term referring to any drug marketed under its chemical name without advertising.

Generic name, drug
The term "generic name" has several meanings as regards drugs: The chemical name of a drug. A term referring to the chemical makeup of a drug rather than to the advertised brand name under which the drug is sold. A term referring to any drug marketed under its chemical name without advertising.

Generic view
A view of an object that is not special. In other words, the view won't change drastically with small perturbations in lighting or viewing direction.

Generlac
Generlac is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): lactulose.

Genes
Basic, functional units of heredity, each occupying a specific place on a chromosome.

Genes, breast cancer susceptibility
Inherited factors that predispose to breast cancer. Put otherwise, these genes make one more susceptible to the disease and so increase the risk of developing breast cancer. Two of these genes, BRCA1 and BRCA2, have been identified (and prominently publicized). Several other genes (those for the Li-Fraumeni syndrome, Cowden disease, Muir-Torre syndrome, and ataxia-telangiectasia) are also known to predispose to breast cancer. However, since all of these known breast cancer susceptibility genes together do not account for more than a minor fraction (1/5th at most) of breast cancer that clusters in families, it is clear that more breast cancer genes remain to be discovered.

Genesa
Genesa is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): arbutamine hydrochloride.

Genesis
The beginning of a process.

Genesis Medical Center
Genesis Medical Center is a hospital in Davenport, Iowa (USA).

Genesys Regional Regional Medical Center
Genesys Regional Regional Medical Center is a hospital in Grand Blanc, Michigan (USA).

Genetic
Hereditary. Having to do with the genes.

Genetic anticipation
A remarkable phenomenon in which a genetic disease appears earlier appearance and with increased from with each succeeding generation. Anticipation was once thought not to exist in genetics. It was chalked off as a meaningless statistical artifact. However, anticipation has now been proven to occur in a large number of important genetic disorders, including Huntington disease and myotonic dystrophy. In molecular terms, anticipation is due to the expansion of a trinucleotide repeat sequence in the DNA. This phenomenon also occurs in the fragile X syndrome, the most common inherited form of mental retardation.

Genetic counseling
Providing information, advice, and testing to prospective parents at risk of having a child with a birth defect or genetic disorder.

Genetic counselor
A health professional with a specialized graduate degree and experience in the areas of medical genetics and counseling. Genetic counselors enter the field from a variety of disciplines, including biology, genetics, nursing, psychology, public health and social work.

Genetic discrimination
The potential use of genetic information to discriminate against people in the workplace, in health insurance, or in any other arena.

Genetic disorder
A disease or condition caused by an abnormality in a person's genetic blueprint. Such conditions include chromosomal disorders involving too much or too little chromosomal material, mutations of genes on the chromosomes, and mutations in conjunction with environmental factors such as exposure to drugs or radiation.

Genetic infantile agranulocytosis
Children born with this condition lack neutrophils (a type of white blood cell that is important in fighting infection). These children suffer frequent infections from bacteria which in the past led to death in three-quarters of cases before 3 years of age. This disease is also known as severe congenital neutropenia (SCN).

Genetic information
A DNA sequence (sometimes genetic sequence) is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, The possible letters are A, C, G, and T, representing the four nucleotide subunits of a DNA strand (adenine, cytosine, guanine, thymine), and typically these are printed abutting one another without gaps, as in the sequence AAAGTCTGAC. This coded sequence is sometimes referred to as genetic information.

Genetic inheritance
DNA that is passed from parents to children.

Genetic meltdown
A genomic crisis due to an extraordinarily high rate of mutation, a phenomenon known to occur in viruses and perhaps in other organisms. For example, the antiviral agent Ribavirin acts by inducing genomic meltdown. The drug accelerates the already-high mutation rate of RNA viruses, creates a genomic crisis, and destroys the infectivity of the virus. There is a limit to how much variation a genome can tolerate without irretrievably degrading its genetic information. If a population of viruses is replicating at the brink, just a bit of extra pressure from a mutagen, such as ribavirin, can nudge it into the abyss of genetic meltdown, resulting in an inability for it to replicate and survive.

Genetic screening
Any test used to find genetic abnormalities.

Genetic testing
Tests done for clinical genetic purposes. Genetic tests may be done for diverse purposes pertaining to clinical genetics, including the diagnosis of genetic disease in children and adults; the identification of future disease risks; the prediction of drug responses; and the detection of risks of disease to future children.

Genetic transformation
A process by which the genetic material carried by an individual cell is altered by the incorporation of foreign (exogenous) DNA into its genome.

Genetic transport defect
Within the body, many molecules are able to pass across the membranes that surround cells. These molecules can accomplish this feat due to specific transport systems. These systems include special receptors on the membrane of the cell and special carrier proteins. The receptor recognizes the molecule and receives it on the cell membrane. Then the molecule hitches a ride through the cell membrane on the back of a carrier protein.

Genetic transposition
The ability of genes to change position on chromosomes, a process in which a transposable element is removed from one site and inserted into a second site in the DNA. Genetic transposition was the first type of genetic instability to be discovered.

Genetics
The scientific study of heredity. Genetics pertains to humans and all other organisms. So, for example, there is human genetics, mouse genetics, fruitfly genetics, etc.

Genetics, transplantation
The field of biology and medicine relating to the genes that govern the acceptance or rejection of a transplant.

Geneve doctors
All doctors near Geneve, Switzerland. Doctors who can assist a patient in Geneve.

PREVIOUS AND NEXT TERMS
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Gene, Med1 DNA repair
A gene that codes for one of the key enzymes involved in repairing DNA. The DNA in genes is constantly mutating and being repaired. This repair process is controlled by special genes. A mutation in a DNA repair gene such as Med1 can cripple the repair process and cause a cascade of unrepaired mutations in the genome that lead to cancer.

Gene, regulatory
A gene that regulates the expression of other genes. A regulatory gene is a nosy gene whose prime preoccupation is to horn in on other genes and control the rate at which they make products.

Gene, suicide
A gene whose expression in a cell is lethal for that cell. Suicide genes form the basis of a strategy for making cancer cells more vulnerable, more sensitive to chemotherapy. The approach has been to attach parts of genes expressed in cancer cells to other genes for enzymes not found in mammals that can convert a harmless substance into one that is toxic to the tumor.

Gene, transporter
A gene that allows drugs to enter cells or, in some cases, acts to keep them out. Transporter genes may account for discrepancies in the way drugs such as antidepressants, anticonvulsants, and chemotherapy agents work in different people. Also known as a drug-transporter gene.

Gene, Y-linked
A gene on the Y chromosome. Y-linkage is analogous to X-linkage (the presence of a gene on the X chromosome) in that it says a gene is on one of the sex chromosomes.

Gene, zygotic lethal

Gene-expression profiling
A genomic technique that based on the fact that only a fraction of the genes encoded in the genome of a cell are expressed by being transcribed into messenger RNA (mRNA). The complement of mRNAs in a cell largely dictates its complement of proteins. Consequently, gene expression is a major determinant of the biology of both normal and malignant cells.

General paresis
Progressive dementia and generalized paralysis due to chronic inflammation of the covering and substance of the brain (meningoencephalitis). General paresis is a part of late (tertiary) syphilis, occurring a decade or more after the initial infection.

Generalized anxiety disorder
Abbreviated GAD. A condition characterized by 6 months or more of chronic, exaggerated worry and tension that is unfounded or much more severe than the normal anxiety most people experience. People with GAD usually expect the worst. They worry excessively about money, health, family, or work, even when there are no signs of trouble. They are unable to relax and often suffer from insomnia. Sometimes the source of the worry is hard to pinpoint. Simply the thought of getting through the day provokes anxiety. Many people with GAD also have physical symptoms, such as fatigue, trembling, muscle tension, headaches, irritability or hot flashes. People with GAD may feel lightheaded or out of breath. They also may feel nauseated or have to go to the bathroom frequently. Nearly 3% of the adult US population age 18 to 54 has GAD during the course of a given year. GAD most often strikes in childhood or adolescence, but can also begin in adulthood. It affects women more often than men, may run in families, and may also grow worse with stress. GAD often coexists with depression, substance abuse, and other anxiety disorders. Irritable bowel syndrome, often accompanies GAD. Treatment for GAD includes medications and cognitive-behavioral therapy.

Generic drug
The term "generic" has several meanings as regards drugs: The chemical name of a drug. A term referring to the chemical makeup of a drug rather than to the advertised brand name under which the drug is sold. A term referring to any drug marketed under its chemical name without advertising.

Generic name, drug
The term "generic name" has several meanings as regards drugs: The chemical name of a drug. A term referring to the chemical makeup of a drug rather than to the advertised brand name under which the drug is sold. A term referring to any drug marketed under its chemical name without advertising.

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This dictionary contains 25007 terms.

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