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Topic: Recessive allele

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  International Space School Educational Trust ISSET
The dominant allele is the allele whose phenotype appears in the heterozygote (dominance and recessivity are only meaningful in diploids).
The recessive allele is the allele whose phenotype is masked in the heterozygote.
Note that a mutant is defined relative to wild-type and a dominant allele is defined relative to a recessive allele.
www.isset.org /doc.php?pagelocation=9&group=506&file=page2   (632 words)

  Recessive gene - Wikipedia, the free encyclopedia
Autosomal recessive is a mode of inheritance of genetic traits located on the autosomes (the 22 non-sex determining chromosomes).
Recessive genetic disorders occur when both parents are carriers and each contributes an allele to the embryo.
Recessive genes are usually represented by a lowercase letter in a Punnett square, as opposed to the uppercase letters of dominant genes (see example at right).
en.wikipedia.org /wiki/Recessive_gene   (741 words)

 Gene and Alleles
An allele of a gene is it's partner gene, for example b is an allele of B and vice versa.
Alleles are located in corresponding parts of homologous chromosomes, only one member of a pair can be present in a given chromosome and only two are present in a cell of a diploid.
Alleles are genes that are members of the same gene pair, each kind of allele affecting a trait differently than the other.
library.thinkquest.org /20465/genes.html   (1799 words)

 recessive gene
Allele (alternative form of a gene) that will show in the (phenotype observed characteristics of an organism) only if its partner allele on the paired chromosome is similarly recessive.
Alleles for blue eyes in humans and for shortness in pea plants are recessive.
Sometimes the allele that produces the dominant characteristic is described as being a dominant allele and the one that tends to produce the recessive characteristic as being the recessive allele.
www.tiscali.co.uk /reference/encyclopaedia/hutchinson/m0008099.html   (481 words)

 In the Mode: How Traits Pass in Dogs, Lines and Breeds
The allele for fl is dominant; the allele for liver is recessive.
Dogs with two recessive alleles are not merle, heterozygotes will be merle patterned, and those with two dominant alleles not only have merle patterning but frequently have considerable amounts of white markings and almost always have serious eye defects and deafness.
As a result the most recessive allele for white markings is now extremely rare and may even be purged from the breed gene pool.
www.dogstuff.info /traits_pass_sharp.html   (3108 words)

 Recessive gene Summary
Autosomal recessive is a mode of inheritance of genetic traits located on the autosomes (the 22 non-sex determining chromosomes).
Recessive genetic disorders occur when both parents are carriers and each contributes an allele to the embryo.
Recessive genes are usually represented by a lowercase letter in a Punnett square, as opposed to the uppercase letters of dominant genes (see example at right).
www.bookrags.com /Recessive_gene   (1496 words)

 Geneinfo - Patterns of inheritance
Recessive alleles on the X chromosome show a special pattern of inheritance called X-linked inheritance, because females have two X chromosomes while males have only one.
A recessive allele on the X chromosome does not influence the phenotype in females if it is present in only one copy, because there is a second copy to block it.
While the model of dominant and recessive alleles is useful for understanding many traits that are determined by a single gene, most human characteristics are actually determined by interactions between many genes, as well as environmental factors.
www.geocities.com /geneinfo/concepts/inheritedfr.html   (1141 words)

 Dominance relationship Summary
The allele not expressed in the heterozygous form is said to be recessive to the masking allele, the dominant allele.
The specific variations possible for a single gene are called alleles: for a single eye-color gene, there may be a blue eye allele, a brown eye allele, a green eye allele, etc. Consequently, a child may inherit a blue eye allele from their mother and a brown eye allele from their father.
The dominant allele is purple and the recessive allele is white.
www.bookrags.com /Dominance_relationship   (1570 words)

 discussion of the genetic inheritance of curly hair in horses
The expressed allele in a heterozygous pair is known as the dominant allele, the unexpressed one as the recessive allele.
The term dominant is given an allele only to describe its relationship to related alleles, and is not to be taken as an indication of any kind of physical or temperamental strength of the allele or the animal possessing it.
The presence of a recessive allele may be masked by a dominant allele, which leads to the expression "hidden recessive".
www.curlyhorses.org /allele.html   (699 words)

Dominant alleles -- A dominant allele is not dominant because it "subdues" and "mutes" a recessive allele.
In general, a recessive allele usually codes for a bad (malfunctioning) or missing protein; a single dominant allele is enough to produce enough enzyme to provide the normal phenotype.
There are three alleles involved; A and B alleles each somehow specify a particular carbohydrate that resides on the surface of blood cells.
www.botany.uga.edu /~darley/btny1210/Nov13Fri.htm   (1377 words)

 Principles in Biology - Genetics according to Gregor Mendel
An allele that cannot exert an effect in the presence of a dominant allele is called a recessive gene.
The term 'recessive' says that while the effect cannot be seen in some individuals, the allele itself is still present (only in one copy) and can thus be passed on the next generation.
This observation of two alleles controlling the phenotype of a characteristics and the existence of dominant and recessive alleles was the single most important contribution of Mendel to genetics.
www.whatislife.com /principles/principles12-mendel.htm   (587 words)

 MCDB 2150 -- Lecture 21
Dominant and recessive alleles; genotype and phenotype: The genotype of the individual that develops from the zygote is the sum of all of the genes inherited from both parents, including those that are not overtly expressed.
If one allele is completely dominant over the other, the phenotype of the heterozygote will be the same as the dominant homozygous phenotype, with the alternative phenotype occurring only in individuals who are homozygous for the recessive allele.
A recessive allele is designated with a lower case letter or small group of letters, and a dominant allele is designated with a capital letter, which may be followed by one or more lower case letters.
www.colorado.edu /MCDB/MCDB2150Fall/notes99/99L21.html   (2800 words)

 Bio182PopGenQ.html   (Site not responding. Last check: 2007-10-20)
The frequency for the dominant allele is__d__ while (and) the frequency for the recessive allele is __e__.
The frequency for the dominant allele is __i__ while (and) the frequency for the recessive allele is __j__.
The frequency for the dominant allele is __w__ while (and) the frequency for the recessive allele is __x__.
gecko.gc.maricopa.edu /~rbowker/Bio182PopGenQ.html   (1721 words)

 Tonkinese Genetics
The uppercase letter is used to denote the dominant allele and the lowercase the recessive allele.
For a recessive allele to be visible, both of the pair must be the same recessive allele.
The second allele of the gene pair is the hidden or passive gene, because it does not have any visible effect on the color.
www.tonkinesebreedassociation.org /tonkgenetics.html   (4611 words)

 Zoology 304, Evolution
That is, both alleles necessarily change frequency at the same rate, and that rate is greater when the allele at lower frequency is dominant.
A recessive allele with initial frequency of 95% is shown in yellow.
Here is a graphical representation for a dominant allele, presuming a rather high initial frequency of 1 in a million (i.e., a fairly small, isolated sub-population of people, as if Chicago were surrounded by an impassable desert).
www.science.siu.edu /zoology/king/304/prob04.htm   (665 words)

 Pop. Gen. Solutions   (Site not responding. Last check: 2007-10-20)
S is the dominant allele, while s is the recessive allele.
L is the dominant allele, while l is the recessive allele.
P is the dominant allele, while p is the recessive allele.
www.clt.astate.edu /mhuss/new_page_7.htm   (292 words)

 MSN Encarta - Evolution
If a child inherits the allele for tongue rolling from one parent and the allele for no tongue rolling from the other parent, she will be able to roll her tongue.
The allele for tongue rolling dominates the gene pair, and so its trait is expressed.
According to the laws governing heredity, when a dominant allele (in this case, tongue rolling) and a recessive allele (no tongue rolling) combine, the trait will always be dictated by the dominant allele.
encarta.msn.com /encyclopedia_761554675/Evolution.html   (1780 words)

 Human Genetics - Population Genetics
Those that had the sickle cell anemia allele survived, and the gene remains in the population at high frequency today, even though the homozygous recessive phenotype was at a severe disadvantage in the past.
For an autosomal recessive disease with a population frequency of 1/10,000, the carrier frequency is 1/50.
Gene frequencies for nonfunctional alleles tend to increase in the population because of recurrent mutation.
www.uic.edu /classes/bms/bms655/lesson13.html   (3937 words)

 3423 Animal Genetics - Oklahoma State
Many recessive alleles are extremely harmful when homozygous, so there is selection in every generation that tends to reduce the allele frequency.
A male with at least one copy of the pattern baldness allele (PB) is bald; however, two copies of this allele must be present for a female to be bald.
The frequency of an allele in a large, closed randomly mating population is 0.2.
www.ansi.okstate.edu /course/3423/buchanan/study/study22.htm   (881 words)

 Angelfish Genetics
Recessive: When different alleles occur at the same locus and one of the alleles is not expressed in the presence of the other, the non-expressed trait is considered recessive.
Dominant: When different alleles occur at the same locus and one of the alleles is not expressed in the presence of the other, the expressed trait is considered dominant.
The angelfish of unknown genotype is crossed to a homozygous recessive individual.
www.angelsplus.com /genetics.htm   (2188 words)

 Heredity and Meiosis   (Site not responding. Last check: 2007-10-20)
If the allele for eye color on the homologous chromosome is recessive, it produces a lighter colored pigment that is "hidden" by the darker pigment produced by the dominant allele.
Dominant alleles may be either "good" and produce a healthy condition, even in the presense of a defective recessive allele.
Recessive alleles at gene loci for important proteins may produce proteins that are not functional and unable to do the job they are supposed to do.
www.life.uiuc.edu /bio100/lectures/f04lects/11f04-heredity.html   (1328 words)

  The allele for free-hanging earlobes is dominant and the allele for attached earlobes is recessive.
indicating that you have the dominant allele on one chromosome carrying the gene for this trait, but we don't know what allele you are carrying on the homologous chromosome.
  She was a carrier for the recessive allele for this trait and since her children married into many of the courts of Europe, the disease cropped up in a number of royal families.
www.piercecollege.edu /departments/lifesci/LAB15.htm   (5562 words)

The recessive allele is always represented by the small case letter of the symbol for the dominant allele.
Alleles usually occur in pairs which are segregated (separated) during gamete formation.
To determine the unknown allele we cross the parent with a homozygous recessive (aa) and compare the expected phenotypic ratios with the actual phenotypic ratios of the offspring.
www.personal.psu.edu /faculty/w/x/wxm15/Online/Classical%20Genetics/class_genetics_lec.htm   (5583 words)

 Genetics and Inheritance
An allele that can be suppressed during a generation is called a recessive allele, while one that is consistently expressed is a dominant allele.
Mendel observed that although the dominant trait was the one expressed in the F1 generation, the recessive trait still had an effect on the genotype of a heterozygote's offspring.
When close relatives mate, it increases the chances of recessive alleles (which might be rare in the general population) being passed on by both parents.
www.dartmouth.edu /~cbbc/courses/bio4/bio4-1997/01-Genetics.html   (3601 words)

 Mendelian Genetics
A heterozygous plant (allele for the purple and the allele for the white flower are present) has a purple flower, identifying purple as the dominant trait.
Morgan concluded that the eye color is determined by a dominant allele (red) and a recessive allele (white), located on the X chromosome, while the Y chromosome has no locus for eye color.
The recessive allele causing the disease is designated g, the dominant allele coding for the correct enzyme is designated G.
www.prism.gatech.edu /~gh19/b1510/mendel.htm   (2758 words)

 THE Book on TALL Cotons, Page 4
If a recessive allele is homozygous, than it is expressed in the phenotype, i.e.
Therefore, a breeder can readily fix a dominant allele in his or her bloodline, but may have considerable difficulty eliminating an undesirable recessive allele.
Allele H is dominant over the recessive allele h.
members.aol.com /captlemur/Tall_Genes4.html   (466 words)

 Re: When dose a recessive allele take ove the dominant allele
I am sorry to say that your parents may have misunderstood the genetic explaination of the disease.
A recessive allele never takes over a dominant allele.
Cerebral Palsy, however, is mostly caused by infection, stroke (due to many rasons, such as abnormal blood cells),oxygen loss during pregnancy or child birth, jaundice, and Rh incompatibility.
www.madsci.org /posts/archives/jun2001/991773039.Ge.r.html   (358 words)

Well, remember that since both alleles of a particular gene are expressed equally in the phenotype in codominance, one would expect some sort of intermediate phenotype between the phenotypes seen in the homozygotes for each allele.
(recessive phenotype for gene #1 - recessive phenotype for gene #2)
However, if a female inherits an X chromosome that carries on it a recessive mutation, she can still be healthy (no disease phenotype) provided she inherits a normal copy of the allele on her other X chromosome.
www.cofc.edu /poolel/Ext_Mendel.htm   (2803 words)

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