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Dark Budgerigar Mutation
The Dark budgerigar mutation is one of approximately 30 mutations affecting the colour of budgerigars. It is part of the genetic constitution of the following recognised varieties: Dark Green and Olive in the green series and Cobalt, Mauve and Violet in the blue series. Appearance Budgerigars carrying the Dark factor are identical to the wild-type Light Greens or Skyblues in every respect except body colour and tail feathers. The body is darker in Dark Greens and Cobalts and darker still in Olives and Mauves, and the long tail feathers are darker in proportion. All these varieties have normal violet cheek patches. The Dark Green's body colour is a rich shade of forest green, and Cobalt's a deeper blue, approximating to azure. The Olive is a rich olive similar in shade to a Grey-green, but it may be easily distinguished by its cheek patch, which is violet in the Olive and grey in the Grey-green. The Mauve is a dull purplish gray, quite different from the brilliant Violet an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Budgerigar
The budgerigar ( ; ''Melopsittacus undulatus''), also known as the common parakeet, shell parakeet or budgie ( ), is a small, long-tailed, seed-eating parrot native to Australia. Naturally the species is green and yellow with black, scalloped markings on the nape, back, and wings. Budgies are bred in captivity with colouring of blues, whites, yellows, greys, and even with small crests. Juveniles and chicks are monomorphic (the sexes are visually indistinguishable), while adults are told apart by their cere colouring and their behaviour. The species is monotypic, meaning it is the only member of the genus ''Melopsittacus'', which is the only genus in the Melopsittacini tribe. The budgerigar is closely related to lories and the fig parrots. The origin of the budgerigar's name is unclear. First recorded in 1805, budgerigars are popular pets around the world due to their small size, low cost, and ability to mimic human speech. They are likely the third most popular pet in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wild-type
The wild type (WT) is the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard "normal" allele at a locus, in contrast to that produced by a non-standard, " mutant" allele. "Mutant" alleles can vary to a great extent, and even become the wild type if a genetic shift occurs within the population. Continued advancements in genetic mapping technologies have created a better understanding of how mutations occur and interact with other genes to alter phenotype. It is now regarded that most or all gene loci exist in a variety of allelic forms, which vary in frequency throughout the geographic range of a species, and that a uniform wild type does not exist. In general, however, the most prevalent allele – i.e., the one with the highest gene frequency – is the one deemed wild type. The concept of wild type is useful in some experimental organisms such as fruit flies ''Drosophila melanogaster'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromatid
A chromatid (Greek ''khrōmat-'' 'color' + ''-id'') is one half of a duplicated chromosome. Before replication, one chromosome is composed of one DNA molecule. In replication, the DNA molecule is copied, and the two molecules are known as chromatids. During the later stages of cell division these chromatids separate longitudinally to become individual chromosomes. Chromatid pairs are normally genetically identical, and said to be homozygous. However, if mutations occur, they will present slight differences, in which case they are heterozygous. The pairing of chromatids should not be confused with the ploidy of an organism, which is the number of homologous versions of a chromosome. Sister chromatids Chromatids may be sister or non-sister chromatids. A sister chromatid is either one of the two chromatids of the same chromosome joined together by a common centromere. A pair of sister chromatids is called a dyad. Once sister chromatids have separated (during the anaphase of m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Recombination Frequency
Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Two genetic markers that are physically near to each other are unlikely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be more ''linked'' than markers that are far apart. In other words, the nearer two genes are on a chromosome, the lower the chance of recombination between them, and the more likely they are to be inherited together. Markers on different chromosomes are perfectly ''unlinked'', although the penetrance of potentially deleterious alleles may be influenced by the presence of other alleles, and these other alleles may be located on other chromosomes than that on which a particular potentially deleterious allele is located. Genetic linkage is the most prominent exception to Gregor Mendel's Law of Independent Assortment. The first experiment to demonstrate lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Linkage
Genetic linkage is the tendency of Nucleic acid sequence, DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Two Genetic marker, genetic markers that are physically near to each other are unlikely to be separated onto different Chromatid, chromatids during chromosomal crossover, and are therefore said to be more ''linked'' than markers that are far apart. In other words, the nearer two Gene, genes are on a chromosome, the lower the chance of Genetic recombination, recombination between them, and the more likely they are to be inherited together. Markers on different chromosomes are perfectly ''unlinked'', although the penetrance of potentially deleterious alleles may be influenced by the presence of other alleles, and these other alleles may be located on other chromosomes than that on which a particular potentially deleterious allele is located. Genetic linkage is the most prominent exception to Gregor M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autosome
An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes is collectively known as atDNA or auDNA. For example, humans have a diploid genome that usually contains 22 pairs of autosomes and one allosome pair (46 chromosomes total). The autosome pairs are labeled with numbers (1–22 in humans) roughly in order of their sizes in base pairs, while allosomes are labelled with their letters. By contrast, the allosome pair consists of two X chromosomes in females or one X and one Y chromosome in males. Unusual combinations XYY, XXY, XXX, XXXX, XXXXX or XXYY, among other irregular combinations, are known to occur and usually cause developmental abnormalities. Autosomes still contain sexual determination genes even though they are not sex chromosomes. For example, the SRY gene on the Y chromos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locus (genetics)
In genetics, a locus (: loci) is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of Human genome#Coding sequences (protein-coding genes), protein-coding genes in a complete haploid set of 23 chromosomes is estimated at 19,000–20,000. Genes may possess multiple variants known as alleles, and an allele may also be said to reside at a particular locus. Diploid and polyploid cells whose chromosomes have the same allele at a given locus are called homozygote, homozygous with respect to that locus, while those that have different alleles at a given locus are called heterozygote, heterozygous. The ordered list of loci known for a particular genome is called a gene map. Gene mapping is the process of determining the specific locus or loci responsible for producing a particular phenotype or biological trait. Association ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homozygote
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] |
Allele
An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule. Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), but they can also have insertions and deletions of up to several thousand base pairs. Most alleles observed result in little or no change in the function or amount of the gene product(s) they code or regulate for. However, sometimes different alleles can result in different observable phenotypic traits, such as different pigmentation. A notable example of this is Gregor Mendel's discovery that the white and purple flower colors in pea plants were the result of a single gene with two alleles. Nearly all multicellular organisms have two sets of chromosomes at some point in their biological life cycle; that is, they are diploid. For a given locus, if the two chromosomes contain the same allele, they, and the organism, are homozygous with re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dominance Relationship
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 is called 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 Y chromosome, Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance, such as incomp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forest Green
Forest green is a green color said to resemble the color of the trees and other plants in a forest. This web color, when written as computer code in HTML for website color display, is written in the form forestgreen (no space). The first recorded use of ''forest green'' as a color name in English was in 1810. ''Forest green'' is a representation of the average color of the leaves of the trees of a temperate zone deciduous forest. Shades Forest green (Crayola) Displayed at right is the color called "forest green" in Crayola crayons. ''Forest green'' has been a Crayola crayon name since 1958, when it was renamed from ''dark green''. Tropical rainforest Displayed at right is the color tropical rainforest, a bluish-shade of forest green. The color ''tropical rainforest'' was formulated by Crayola in 1993. In culture Cartography * Forest green is used to represent deciduous forest on maps depicting ''natural vegetation''. Environmentalism * Forest green may be use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
