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Topic: Recessive gene


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In the News (Fri 19 Jul 19)

  
  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).
Technically, the term "recessive gene" is imprecise because it is not the gene that is recessive but the phenotype (or trait).
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   (825 words)

  
 Recessive Gene Transmission - Picture - MSN Encarta
In these cases, two copies of the recessive gene are required for the disease to occur.
A person who has just one copy of the recessive gene is termed a carrier, since he or she carries the gene but is not affected by it.
The children on the far left received the recessive gene from their father and the dominant gene from their mother, and are therefore carriers.
encarta.msn.com /media_461547549_761566075_-1_1/Recessive_Gene_Transmission.html   (264 words)

  
 Dominant gene - Wikipedia, the free encyclopedia   (Site not responding. Last check: 2007-10-06)
In genetics, the term dominant gene refers to the allele that causes a phenotype that is seen in a heterozygous genotype.
A dominant gene when written in a genotype is always written before the recessive gene in a heterozygous pair.
Incomplete dominance occurs when certain of the recessive gene appears within the phenotype of the organism, causing a blend in between both the dominant and recessive gene.
en.wikipedia.org /wiki/Dominant_gene   (345 words)

  
 Wikinfo | Recessive gene
In genetics, the term "recessive gene" refers to an allele that causes a phenotype (visible or detectable characteristic) that is only seen in a homozygous genotype (an organism that has two copies of the same allele).
Technically, the term "recessive gene" is inprecise because it is not the gene that is recessive but the phenotype (or trait).
Recessive genes are usually represented by a lowercase letter in a Punnett square, as opposed to the uppercase letters of dominant genes.
www.wikinfo.org /wiki.php?title=Recessive   (368 words)

  
 Sex-linked recessive   (Site not responding. Last check: 2007-10-06)
The term "sex-linked recessive" means that an abnormal gene on the X chromosome from each parent is required to cause the disease in females since the female has 2 X chromosomes.
The inheritance of genetic diseases, abnormalities, or traits is described by both the type of chromosome the abnormal gene resides on (autosome or sex chromosome), and by whether the gene itself is dominant or recessive.
The recessive gene is expressed in the male because there is not another X to counteract it, only the Y (which determines for maleness).
www.shands.org /health/information/article/002051.htm   (617 words)

  
 [No title]
Allelic genes (genes that have the same location or locus on a chromosome, which are also genes that substitute for one another) are grouped together.
The smoky gene is an allele belonging to the dominant white locus.
This gene is considered to be the wild-type because it is present in the Jungle Fowl.
marsa_sellers.tripod.com /geneticspages/page3.html   (2647 words)

  
 Autosomal recessive verses autosomal dominant retinitis pigmentosa
In the first case, where a person has one normal and one altered gene, a person is said to be a carrier; in the second case, where no normal gene is present, the person is said to have autosomal recessive retinitis pigmentosa.
Nonetheless, the recessive trait for retinitis pigmentosa, while not expressed due to the presence of a 'normal' gene, is still part of the genome and may be passed to the next generation.
The normal gene is ineffective against overriding the affects of the mutant gene.
www.geocities.com /retinitis_pigmentosa_rp/r_pigmentosa_autorecess.html   (972 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.
If the two genes are identical (homozygous state) the characteristic seen in the organism is determined by the two genes.
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   (496 words)

  
 Geneinfo - Patterns of inheritance
As discussed in the section on meiosis and mitosis, we have two copies of each gene, one which comes from the mother in her egg and one which comes from the father in his sperm.
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)

  
 Autosomal Recessive: Cystic Fibrosis, Sickle Cell Anemia, Tay Sachs Disease - Lucile Packard Children's Hospital
"Recessive" means that two copies of the gene are necessary to have the trait, one inherited from the mother, and one from the father.
A person who has only one recessive gene is said to be a "carrier" for the trait or disease, but they do not have any health problems from "carrying" one copy of the gene.
Once parents have had a child with a recessive trait or disease, there is a one out of four, or 25 percent chance, with each subsequent pregnancy, for another child to be born with the same trait or disorder.
www.lpch.org /DiseaseHealthInfo/HealthLibrary/genetics/recessive.html   (1013 words)

  
 Gene Abnormalities: Genetics: Merck Manual Home Edition
An abnormal gene may be inherited or may arise spontaneously as a result of a mutation (a sudden change in a gene arising as a result of any one of a number of causes or for no apparent cause at all).
Finally, all genes residing on the X chromosome (X-linked) are expressed in males; only dominant ones are expressed in females (unless two copies of a recessive gene are present).
When one parent has the trait and the other has one recessive gene but does not have the trait, half of their children are likely to have the trait; the others will be carriers with one recessive gene.
www.merck.com /mmhe/sec01/ch002/ch002b.html   (1818 words)

  
 CIDD- Introduction
A gene is a portion of a DNA molecule, carried on a chromosome.
As long as the frequency of a gene for a recessive disorder remains low in the population, the particular gene may be passed along for many generations before by chance 2 carriers are mated and affected individuals are born.
However, the gene frequency may become unusually high due to breeding of close family members, or because of the "popular sire" effect, where a sire with a harmful recessive gene is mated frequently because of desirable traits.
www.upei.ca /~cidd/howare.htm   (1647 words)

  
 ulrikain   (Site not responding. Last check: 2007-10-06)
But then we should also consider the fact that if the gene frequencies of some recessive defects are low, the chances for the defect to show up (the probability for an individual to be homozygous for that recessive defect gene) is a lot smaller in an outcrossed population.
The probability for both parents in a mating to carry this recessive gene is 0.05 x 0.05 =0.0025 or 0.25 %.
In this mating the probability is 0.25 % for a kitten to be homozygous for the defect gene.
bowen1.home.mindspring.com /mchs/articles/ulrikain.htm   (580 words)

  
 THE RECESSIVE GENE AND INFERTILITY
We are dealing here with the simple idealized case where there are no other effects of the gene other than to cause infertility in persons with a copy of the gene from both parents and that has no effect on carriers (who have the gene from one or other of their parents but not both).
If we denote n for a normal gene and g for the recessive gene: H people have nn genes and are healthy, proportion x C people have ng genes are carriers, proportion 1-x D people have gg genes and do not survive to produce offspring.
Contrary to popular belief, a stable population of carriers of a recessive gene that causes infertility can exist at a figure of 59.6% of the fertile population (41.4% not carrying the gene), assuming a large population with randomly chosen parents for each generation of offspring.
www.davidb67.clara.net /gene_rec.htm   (799 words)

  
 Family Tree and Recessive Genes
The Punnett square shows the probability with the symbol for brown eye gene upper case B since it is dominant and the symbol for the blue eyes gene lower case b since it is recessive.
If two parents are carriers of the same recessive gene, then the chances of the recessive condition showing up in their children is 1 in 4 for each pregnancy.
A rare gene may exist in a population for a condition that is either dominantly or recessively inherited.
www.newton.dep.anl.gov /askasci/mole00/mole00289.htm   (1026 words)

  
 Genetics Page
It is not uncommon for the inexperienced fancier to confuse recessive opal with dominant opal.
RECESSIVE RED AND RECESSIVE YELLOW: Recessive red is an autosomal recessive gene which masks the underlying basic color (blue-fl, ash-red, or brown) and pattern.
One gene appears to be responsible for the reversal of feathers, while additional "modifier" genes determine whether the reversal appears as a "peak" crest as in Oriental Frills and Archangels, or a "shell" crest as seen in Helmets, Nuns and English Trumpeters.
www.angelfire.com /oh/raraavis/genetics.html   (2928 words)

  
 recessive
Niemann-Pick C Disease is caused by a recessive gene and is ultimately fatal; individuals with the disease are unable to metabolize cholesterol.
Doctors told her it was a "recessive gene" when her second child came down with the same disease and there was a 25 percent chance that her other children...
Tay-Sachs disease is a rare autosomal recessive genetic disorder causing a deficiency in B-hexosaminidase, the enzyme responsible for the breakdown of the...
www.mongabay.com /igapo/biotech/recessive.html   (2617 words)

  
 The Basics on Genes and Genetic Disorders
Genes are sections or segments of DNA that are carried on the chromosomes and determine specific human characteristics, such as height or hair color.
If a person carries the dominant gene for a disease, he or she will usually have the disease and each of the person's children will have a 1 in 2 (50%) chance of inheriting the gene and getting the disease.
People who have one recessive gene for a disease are called carriers, and they don't usually have the disease because they have a normal gene of that pair that can do the job.
kidshealth.org /teen/your_body/health_basics/genes_genetic_disorders.html   (1376 words)

  
 MedlinePlus Medical Encyclopedia: Autosomal recessive
An abnormal gene on one of the autosomal chromosomes (one of the first 22 "non-sex" chromosomes) from each parent is required to cause the disease.
The inheritance of genetic diseases, abnormalities, or traits is described by both the type of chromosome on which the abnormal gene resides (autosomal or sex chromosome), and by whether the gene itself is dominant or recessive.
For an autosomal recessive disorder: When both parents are carriers of an autosomal recessive trait, there is a 25% chance of a child inheriting abnormal genes from both parents, and therefore of developing the disease.
www.nlm.nih.gov /medlineplus/ency/article/002052.htm   (600 words)

  
 Recessive gene
Genes are contained by, and arranged along the length of, the chromosome.
A dominant trait is opposed to a recessive trait which is expressed only when two copies of the gene are present.
If you have a better definition for Recessive gene than the one presented here, please let us know by making use of the suggest a term option.
www.healthdictionary.info /Recessive_gene.htm   (721 words)

  
 Medical Research at Case-First Evidence of Recessive Gene in Alzheimer's Discovered   (Site not responding. Last check: 2007-10-06)
All of the genes identified as playing a role in Alzheimer's are dominant; no recessive genes have been linked to the disease.
A dominant gene will show its effect if it is inherited from only one parent; a recessive gene must be inherited from both parents to show its effect.
"This population is ideal for studying the role of recessive genes in Alzheimer's and other diseases because of the large family size and the amount of intermarrying," said Friedland.
www.cwru.edu /menu/research/alzheimergene.htm   (457 words)

  
 recessive Curly Horses
The Recessive gene Curly Horse is any horse other than a dominant gene North American Curly Horse, that is born curly, and is resulting from two straight haired, non-curly bloodline, non-curly coated, parents.
The recessive gene Curly Horse is another breed of horse, that "crops out" curly, for some undetermined reason.
These recessive curlies, are definitely curly horses, with curly winter coats, and curly hair in their ears.
www.curlyhorses.org /recessive.html   (713 words)

  
 Halfbakery: Recessive gene registry
[Loris] where a recessive condition (like sickle cell) has a survival trait, even though it is harmful to homozygous carriers (well, fatal), it still confers 'fitness' to survive in it's environment for heterozygous carriers, and still follows survival of the fittest.
Genes for which heterozygotes are fitter than either homozygote are by no means unusual.
Every gene has its context; that is, even though a gene may be favourable in some situations it isn't in all.
www.halfbakery.com /idea/Recessive_20gene_20registry   (1190 words)

  
 discussion of the genetic inheritance of curly hair in horses
Often when the gene pair is heterozygous, one allele may be visibly expressed but the other is not.
The expressed allele in a heterozygous pair is known as the dominant allele, the unexpressed one as the recessive allele.
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)

  
 Medical Genetics - X-linked Recessive: Red-Green Color Blindness, Hemophilia A
X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome.
However, for males, there only needs to be one copy of an X-linked recessive gene in order for the trait or disorder to be expressed.
One third of all cases are thought to be new mutations in the family (not inherited from the mother).
www.musckids.com /health_library/genetics/xlink.htm   (390 words)

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