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Heterozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heterozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homozygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hemizygous
Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Most eukaryotes have two matching sets of chromosomes; that is, they are diploid. Diploid organisms have the same loci on each of their two sets of homologous chromosomes except that the sequences at these loci may differ between the two chromosomes in a matching pair and that a few chromosomes may be mismatched as part of a chromosomal sex-determination system. If both alleles of a diploid organism are the same, the organism is homozygous at that locus. If they are different, the organism is heterozygous at that locus. If one allele is missing, it is hemizygous, and, if both alleles are missing, it is nullizygous. The DNA sequence of a gene often varies from one individual to another. These gene variants are called alleles. While some gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development (a ''de novo'' mutation), or it can be Heredity, inherited from two parents who are carriers of a faulty gene (autosomal recessive inheritance) or from a parent with the disorder (autosomal dominant inheritance). When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y linkage, Y chromosome or Mitochondrial disease#Causes, mitochondrial DNA (due to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loss-of-function Mutation
In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosis, or meiosis or other types of damage to DNA (such as pyrimidine dimers caused by exposure to ultraviolet radiation), which then may undergo error-prone repair (especially microhomology-mediated end joining), cause an error during other forms of repair, or cause an error during replication (translesion synthesis). Mutations may also result from insertion or deletion of segments of DNA due to mobile genetic elements. Mutations may or may not produce detectable changes in the observable characteristics (phenotype) of an organism. Mutations play a part in both normal and abnormal biological processes including: evolution, cancer, and the development of the immune system, including junctional diversity. Mutation is the ultimate source of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haploinsufficiency
Haploinsufficiency in genetics describes a model of dominant gene action in diploid organisms, in which a single copy of the wild-type allele at a locus in heterozygous combination with a variant allele is insufficient to produce the wild-type phenotype. Haploinsufficiency may arise from a ''de novo'' or inherited loss-of-function mutation in the variant allele, such that it yields little or no gene product (often a protein). Although the other, standard allele still produces the standard amount of product, the total product is insufficient to produce the standard phenotype. This heterozygous genotype may result in a non- or sub-standard, deleterious, and (or) disease phenotype. Haploinsufficiency is the standard explanation for dominant deleterious alleles. In the alternative case of haplosufficiency, the loss-of-function allele behaves as above, but the single standard allele in the heterozygous genotype produces sufficient gene product to produce the same, standard phenotype ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominance (genetics)
In genetics, dominance is the phenomenon of one variant (allele) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome. The first variant is termed dominant and the second recessive. This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new (''de novo'') or inherited. The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant, X-linked recessive or Y-linked; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage). Since there is only one copy of the Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance such as incomplete d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chinese Hamster Ovary Cell
Chinese hamster ovary (CHO) cells are an epithelial cell line derived from the ovary of the Chinese hamster, often used in biological and medical research and commercially in the production of recombinant therapeutic proteins. They have found wide use in studies of genetics, toxicity screening, nutrition and gene expression, particularly to express recombinant proteins. CHO cells are the most commonly used mammalian hosts for industrial production of recombinant protein therapeutics. History Chinese hamsters had been used in research since 1919, where they were used in place of mice for typing pneumococci. They were subsequently found to be excellent vectors for transmission of kala-azar (visceral leishmaniasis), facilitating '' Leishmania'' research. In 1948, the Chinese hamster was first used in the United States for breeding in research laboratories. In 1957, Theodore T. Puck obtained a female Chinese hamster from Dr. George Yerganian's laboratory at the Boston Cancer R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pronucleus
A pronucleus () is the nucleus of a sperm or egg cell during the process of fertilization. The sperm cell becomes a pronucleus after the sperm enters the ovum, but before the genetic material of the sperm and egg fuse. Contrary to the sperm cell, the egg cell has a pronucleus once it becomes haploid, and not when the sperm cell arrives. Sperm and egg cells are haploid, meaning they carry half the number of chromosomes of somatic cells, so in humans, haploid cells have 23 chromosomes, while somatic cells have 46 chromosomes. The male and female pronuclei do not fuse, although their genetic material does. Instead, their membranes dissolve, leaving no barriers between the male and female chromosomes. Their chromosomes can then combine and become part of a single diploid nucleus in the resulting embryo, containing a full set of chromosomes. The appearance of two pronuclei is the first sign of successful fertilization as observed during in vitro fertilisation, and is usually observed 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microinjection
Microinjection is the use of a glass micropipette to inject a liquid substance at a microscopic or borderline macroscopic level. The target is often a living cell but may also include intercellular space. Microinjection is a simple mechanical process usually involving an inverted microscope with a magnification power of around 200x (though sometimes it is performed using a dissecting stereo microscope at 40–50x or a traditional compound upright microscope at similar power to an inverted model). For processes such as cellular or pronuclear injection the target cell is positioned under the microscope and two micromanipulators—one holding the pipette and one holding a microcapillary needle usually between 0.5 and 5 µm in diameter (larger if injecting stem cells into an embryo)—are used to penetrate the cell membrane and/or the nuclear envelope. In this way the process can be used to introduce a vector into a single cell. Microinjection can also be used in the clon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Y Chromosome
The Y chromosome is one of two sex chromosomes (allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or absence of Y that determines the male or female sex of offspring produced in sexual reproduction. In mammals, the Y chromosome contains the gene SRY, which triggers male development. The DNA in the human Y chromosome is composed of about 59 million base pairs, making it similar in size to chromosome 19. The Y chromosome is passed only from father to son. With a 30% difference between humans and chimpanzees, the Y chromosome is one of the fastest-evolving parts of the human genome. The human Y chromosome carries an estimated 100–200 genes, with between 45 and 73 of these being protein-coding. All single-copy Y-linked genes are hemizygous (present on only one chromosome) except in cases of aneuploidy such as XYY syndrome or XXYY syndrome. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X Chromosome
The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females. It is a part of the XY sex-determination system and XO sex-determination system. The X chromosome was named for its unique properties by early researchers, which resulted in the naming of its counterpart Y chromosome, for the next letter in the alphabet, following its subsequent discovery. Discovery It was first noted that the X chromosome was special in 1890 by Hermann Henking in Leipzig. Henking was studying the testicles of ''Pyrrhocoris'' and noticed that one chromosome did not take part in meiosis. Chromosomes are so named because of their ability to take up staining (''chroma'' in Greek means ''color''). Although the X chromosome could be stained just as well as the others, Henking was unsure whether it was a different class of object and consequently named it ''X element'', which later be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
