|
|
| Line 1: |
Line 1: |
| '''Zygosity''' is the degree of similarity of the [[allele]]s for a trait in an organism. | | By investing in a premium Word - Press theme, you're investing in the future of your website. Offshore expert Word - Press developers high level of interactivity, accessibility, functionality and usability of our website can add custom online to using. Your parishioners and certainly interested audience can come in to you for further information from the group and sometimes even approaching happenings and systems with the church. 2- Ask for the designs and graphics that will be provided along with the Word - Press theme. Over a million people are using Wordpress to blog and the number of Wordpress users is increasing every day. <br><br>These folders as well as files have to copied and the saved. After all, Word - Press is free, many of the enhancements for Word - Press like themes and plugins are also free, and there is plenty of free information online about how to use Word - Press. You are able to set them within your theme options and so they aid the search engine to get a suitable title and description for the pages that get indexed by Google. It primarily lays emphasis on improving the search engine results of your website whenever a related query is typed in the search box. Many times the camera is following Mia, taking in her point of view in almost every frame. <br><br>It is very easy to install Word - Press blog or website. It was also the very first year that the category of Martial Arts was included in the Parents - Connect nationwide online poll, allowing parents to vote for their favorite San Antonio Martial Arts Academy. You can now search through the thousands of available plugins to add all kinds of functionality to your Word - Press site. Enough automated blog posts plus a system keeps you and your clients happy. For any web design and development assignment, this is definitely one of the key concerns, specifically for online retail outlets as well as e-commerce websites. <br><br>It is the convenient service through which professionals either improve the position or keep the ranking intact. I didn't straight consider near it solon than one distance, I got the Popup Ascendancy plugin and it's up and lengthways, likely you make seen it today when you visited our blog, and I yet customize it to fit our Thesis Wound which gives it a rattling uncomparable visage and search than any different popup you know seen before on any added journal, I hump arrogated asset of one of it's quatern themes to make our own. When we talk about functional suitability, Word - Press proves itself as one of the strongest contestant among its other rivals. The most important plugins you will need are All-in-One SEO Pack, some social bookmarking plugin, a Feedburner plugin and an RSS sign up button. If your blog employs the permalink function, This gives your SEO efforts a boost, and your visitors will know firsthand what's in the post when seeing the URL. <br><br>He loves sharing information regarding wordpress, Majento, Drupal and Joomla development tips & tricks. Should you adored this informative article along with you want to get more details concerning [http://xd03.com/WordpressDropboxBackup336541/ backup plugin] generously stop by our own page. Visit our website to learn more about how you can benefit. This allows updates to be sent anyone who wants them via an RSS reader or directly to their email. It is a fact that Smartphone using online customers do not waste much of their time in struggling with drop down menus. Likewise, professional publishers with a multi author and editor setup often find that Word - Press lack basic user and role management capabilities. |
| | |
| Most [[eukaryote]]s 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#Chromosomal determination|sex-determination system]]. If both alleles of a diploid organism are the same, the organism is [[Zygosity#Homozygous| homozygous]] at that locus. If they are different, the organism is [[Zygosity#Heterozygous| heterozygous]] at that locus. If one allele is missing, it is [[Zygosity#Hemizygous| hemizygous]], and, if both alleles are missing, it is [[Zygosity#Nullizygous| nullizygous]].
| |
| | |
| The DNA sequence of a gene often varies from one individual to another. Those variations are called [[alleles]]. While some genes have only one allele because there is low variation, others have only one allele because only that allele can function properly. Any variation from the DNA sequence of that allele will be fatal in the embryo, and the organism will never survive to be born. But most genes have two or more alleles. The frequency of different alleles varies throughout the population. Some genes may have two alleles with equal distribution. For other genes, one allele may be common, and another allele may be rare. Sometimes, one allele is a [[Genetic disorder|disease]]-causing variation while the other allele is healthy. Sometimes, the different variations in the alleles make no difference at all in the function of the organism.
| |
| | |
| In diploid organisms, one allele is inherited from the male parent and one from the female parent. Zygosity is a description of whether those two alleles have identical or different DNA sequences. In some cases the term "zygosity" is used in the context of a single chromosome.<ref>{{cite pmid|16780578}}</ref>
| |
| | |
| ==Types==
| |
| The words homozygous, heterozygous, and hemizygous are used to describe the [[genotype]] of a diploid organism at a single [[locus (genetics)|locus]] on the DNA. ''Homozygous'' describes a genotype consisting of two identical alleles at a given locus, ''heterozygous'' describes a genotype consisting of two different alleles at a locus, ''hemizygous'' describes a genotype consisting of only a single copy of a particular gene in an otherwise diploid organism, and ''nullizygous'' refers to an otherwise-diploid organism in which both copies of the gene are missing.
| |
| | |
| ===Homozygous===
| |
| A cell is said to be homozygous for a particular gene when identical alleles of the gene are present on both [[homologous chromosomes]].<ref name="Henderson's">Lawrence, Eleanor: ''Henderson's Dictionary of Biology, 14e'', 2008</ref> The cell or organism in question is called a '''homozygote'''. [[True breeding organism]]s are always homozygous for the traits that are to be held constant.
| |
| | |
| An individual that is '''homozygous-dominant''' for a particular trait carries two copies of the allele that codes for the [[Dominance (genetics)|dominant]] trait. This allele, often called the "dominant allele", is normally represented by a capital letter (such as "P" for the dominant allele producing purple flowers in pea plants). When an organism is homozygous-dominant for a particular trait, the genotype is represented by a doubling of the symbol for that trait, such as "PP".
| |
| | |
| An individual that is '''homozygous-recessive''' for a particular trait carries two copies of the allele that codes for the [[recessive trait]]. This allele, often called the "recessive allele", is usually represented by the lowercase form of the letter used for the corresponding dominant trait (such as, with reference to the example above, "p" for the recessive allele producing white flowers in pea plants). The genotype of an organism that is homozygous-recessive for a particular trait is represented by a doubling of the appropriate letter, such as "pp".
| |
| | |
| ===Heterozygous===<!-- This section is linked from [[Transgenic maize]] -->
| |
| A [[Ploidy#Diploid|diploid]] organism is heterozygous at a gene locus when its cells contain two different [[allele]]s of a gene.<ref>[http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mcb Molecular Cell Biology], 4th edition by Harvey Lodish, et al [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=mcb&part=A1876#A1877 Chapter 8]. (2000)</ref> The cell or organism is called a '''heterozygote''' ''specifically'' for the allele in question, therefore, heterozygosity refers to a specific genotype. Heterozygous genotypes are represented by a capital letter (representing the dominant allele) and a lowercase letter (representing the recessive allele), such as "Rr" or "Ss". Alternatively, a heterozygote for gene "R" is assumed to be "Rr". The capital letter is usually written first.
| |
| | |
| If the trait in question is determined by simple (complete) dominance, a heterozygote will express only the trait coded by the dominant allele, and the trait coded by the recessive allele will not be present. In [[Dominant_allele#Types_of_dominances|more complex dominance schemes]] the results of heterozygosity can be more complex.
| |
| | |
| ===Hemizygous===
| |
| A chromosome in a diploid organism is hemizygous when only one copy is present.<ref name="Henderson's"/> The cell or organism is called a ''hemizygote''. Hemizygosity is also observed when one copy of a gene is deleted, or in the [[sex linkage|heterogametic]] sex when a gene is located on a sex chromosome. For organisms in which the male is heterogametic, such as humans, almost all X-linked genes are hemizygous in males with normal chromosomes because they have only one [[X chromosome]] and few of the same genes are on the [[Y chromosome]]. Transgenic mice generated through exogenous DNA microinjection of an embryo's pronucleus are also considered to be hemizygous because the introduced allele is expected to be incorporated into only one copy of any locus. A transgenic can later be bred to homozygosity and maintained as an inbred line to reduce the need to confirm the genotypes of each litter.
| |
| | |
| ===Nullizygous===
| |
| A nullizygous organism carries two mutant alleles for the same gene. The mutant alleles are both complete loss-of-function or 'null' alleles, so homozygous null and nullizygous are synonymous.<ref name="Henderson's"/> The mutant cell or organism is called a ''nullizygote''.
| |
| | |
| ==Autozygous and allozygous==
| |
| Zygosity may also refer to the origin(s) of the alleles in a genotype. When the two alleles at a locus originate from a common ancestor by way of nonrandom mating ([[inbreeding]]), the genotype is said to be ''autozygous''. This is also known as being "identical by descent", or IBD. When the two alleles come (at least to the extent that the descent can be traced) from completely different sources, as is the case in most normal, random mating, the genotype is called ''allozygous''. This is known as being "identical by state", or IBS.
| |
| | |
| Because the alleles of autozygous genotypes come from the same source, they are always homozygous, but allozygous genotypes may be homozygous too. All heterozygous genotypes are, by definition, allozygous because they contain two completely different alleles. Hemizygous and nullizygous genotypes do not contain enough alleles to allow for comparison of sources, so this classification is irrelevant for them.
| |
| | |
| ==Monozygotic and dizygotic twins==
| |
| {{Details|Twin|the terms "monozygotic" and "dizygotic"}}
| |
| | |
| As discussed above, "zygosity" can be used in the context of a specific genetic locus (example<ref>{{cite pmid|12654648}}</ref>). In addition, the word "zygosity" may also be used to describe the genetic similarity or dissimilarity of twins.<ref>[http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=hmg Human Molecular Genetics], 2nd edition by Tom Strachan and Andrew P. Read [http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=hmg&part=A2178#A2306 Chapter 17]. (1999).</ref> Identical twins are '''monozygotic''', meaning that they develop from one zygote that splits and forms two embryos. Fraternal twins are '''dizygotic''' because they develop from two separate eggs that are fertilized by two separate [[sperm]].
| |
| | |
| ==Heterozygosity in population genetics==
| |
| In [[population genetics]], the concept of heterozygosity is commonly extended to refer to the population as a whole, i.e., the fraction of individuals in a population that are heterozygous for a particular locus. It can also refer to the fraction of loci within an individual that are heterozygous.
| |
| | |
| Typically, the observed (<math>H_o</math>) and expected (<math>H_e</math>) heterozygosities are compared, defined as follows for diploid individuals in a population:
| |
| | |
| ;Observed
| |
| :<math>H_o = \frac{\sum\limits_{i=1}^{n}{(1\ \textrm{if}\ a_{i1} \neq a_{i2})}}{n}</math>
| |
| where <math>n</math> is the number of individuals in the population, and <math>a_{i1},a_{i2}</math> are the alleles of individual <math>i</math> at the target locus.
| |
| | |
| ;Expected
| |
| :<math>
| |
| H_e = 1 - \sum\limits_{i=1}^{m}{(f_i)^2}
| |
| </math>
| |
| where <math>m</math> is the number of alleles at the target locus, and <math>f_i</math> is the [[allele frequency]] of the <math>i^{th}</math> allele at the target locus.
| |
| | |
| ==See also==
| |
| *[[Heterosis]]
| |
| *[[Heterozygote advantage]]
| |
| *[[Loss of heterozygosity]]
| |
| *[[Nucleotide diversity]] measures polymorphisms on the level of nucleotides rather than on level of loci.
| |
| | |
| ==References==
| |
| {{reflist}}
| |
| | |
| [[Category:Classical genetics]]
| |
By investing in a premium Word - Press theme, you're investing in the future of your website. Offshore expert Word - Press developers high level of interactivity, accessibility, functionality and usability of our website can add custom online to using. Your parishioners and certainly interested audience can come in to you for further information from the group and sometimes even approaching happenings and systems with the church. 2- Ask for the designs and graphics that will be provided along with the Word - Press theme. Over a million people are using Wordpress to blog and the number of Wordpress users is increasing every day.
These folders as well as files have to copied and the saved. After all, Word - Press is free, many of the enhancements for Word - Press like themes and plugins are also free, and there is plenty of free information online about how to use Word - Press. You are able to set them within your theme options and so they aid the search engine to get a suitable title and description for the pages that get indexed by Google. It primarily lays emphasis on improving the search engine results of your website whenever a related query is typed in the search box. Many times the camera is following Mia, taking in her point of view in almost every frame.
It is very easy to install Word - Press blog or website. It was also the very first year that the category of Martial Arts was included in the Parents - Connect nationwide online poll, allowing parents to vote for their favorite San Antonio Martial Arts Academy. You can now search through the thousands of available plugins to add all kinds of functionality to your Word - Press site. Enough automated blog posts plus a system keeps you and your clients happy. For any web design and development assignment, this is definitely one of the key concerns, specifically for online retail outlets as well as e-commerce websites.
It is the convenient service through which professionals either improve the position or keep the ranking intact. I didn't straight consider near it solon than one distance, I got the Popup Ascendancy plugin and it's up and lengthways, likely you make seen it today when you visited our blog, and I yet customize it to fit our Thesis Wound which gives it a rattling uncomparable visage and search than any different popup you know seen before on any added journal, I hump arrogated asset of one of it's quatern themes to make our own. When we talk about functional suitability, Word - Press proves itself as one of the strongest contestant among its other rivals. The most important plugins you will need are All-in-One SEO Pack, some social bookmarking plugin, a Feedburner plugin and an RSS sign up button. If your blog employs the permalink function, This gives your SEO efforts a boost, and your visitors will know firsthand what's in the post when seeing the URL.
He loves sharing information regarding wordpress, Majento, Drupal and Joomla development tips & tricks. Should you adored this informative article along with you want to get more details concerning backup plugin generously stop by our own page. Visit our website to learn more about how you can benefit. This allows updates to be sent anyone who wants them via an RSS reader or directly to their email. It is a fact that Smartphone using online customers do not waste much of their time in struggling with drop down menus. Likewise, professional publishers with a multi author and editor setup often find that Word - Press lack basic user and role management capabilities.