Incomplete dominance: situation in some genes in which the heterozygote is an intermediate (blend) of the parent phenotypes. One example is flower color in carnations and snapdragons. cR= red and cW= white, and red and white individuals are homozygous. The heterozygotes made by crossing these 2 purebred homozygotes are all pink. See the diagram below.
Codominance: there exists more than 1 dominant allele; sometimes there's also a recessive allele. A prime example is with the ABO blood group. "A" indicated the presence of the "A" antigen (glycoprotein) on the surface of the red blood cells, "B" indicates the "B" antigen, "AB" indicates the presence of both, and "O" indicates no antigen is present. The O phenotype is caused by a homozygous recessive condition, while the other phenotypes are caused by the presence of one or two dominant alleles (A and B are both dominant). All possible combinations of alleles and phenotypes are listed below.
Sex-linked genes: Genes found on the X or Y chromosomes (not the autosomes, chromosomes 1-22) are inherited differently between the sexes. Generally speaking, women are XX and men are XY. Any disease associated with the Y chromosome will only be found in men, since women don't receive that chromosome; the X works differently. If a man inherits a recessive (non-functional) allele on his one X chromosome, he is out of luck—he can't make the necessary protein! Women are better off, since they need both X chromosome alleles they inherit to be recessive to show the recessive (diseased) phenotype. Check out the Punnett Square for the sex-linked condition of red-green colorblindness, which is much more common in men.
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ReplyDeleteAccording to Wikipedia Achondroplasia or dwarfism is an autosomal dominant genetic disorder. People with dwarfism have a smaller body size and structure than a person without dwarfism. People with dwarfism have one good copy of the FGFR3 gene and one mutated FGFR3 gene, if a person is born with two of the mutated FGFR3 gene will more then likely to die right after birth. The disorder only need one copy of this gene for the disorder that gives dwarfs a 50% chance of passing on dwarfism. The mutated FGFR3 gene makes the bones grow slower, smaller and bone formation. The physical characteristics of a person with dwarfism is small stature standing at about 4 feet tall with a large skull.
ReplyDeleteSickle cell anemia is an autosomal recessive a genetic disorder caused by a defect in the HBB gene which is coded for hemoglobin.Sickle cells unlike red blood cells can’t squeeze through small blood vessels They instead cause blockages that deprive organs and tissues of blood cells that have oxygen in them. The phenotypes for sickle cell anemia are Hh for heterozygous that person can lead a normal life and hh for homozygous for those who have it.
ReplyDeletePeople usually have three types of cone cells in the eye. Each type senses either red, green, or blue light. You see color when your cone cells sense different amounts of these three basic colors. Most cone cells are found in the macula, which is the central part of the retina.Inherited color blindness happens when you don't have one of these types of cone cells or they don't work right. You may not see one of these three basic colors, or you may see a different shade of that color or a different color. This type of color vision problem doesn't change over time.
ReplyDeleteA color vision problem isn't always inherited. In some cases, a person can have an acquired color vision problem. This can be caused by:
Aging.
Eye problems, such as glaucoma, macular degeneration, cataracts, or diabetic retinopathy.
Injury to the eye.
Side effects of some medicines.
Color blindness is a sex-linked trait that can be inherited and is a recessive allele. The only way males can get it is if one of the parents have a recessive trait and that recessive trait is passed down to the male. The only way a female can be color blind is she has to have two recessive alleles passed down. To get color blindness one of the parents have to have a recessive trait of the disease but this disease isn’t very common in our population but is more common in males than females.
Colorblindness is a sex-linked trait. It is recessive and is carried on the X chromosome. The problem itself occurs when the color sensing pigments in certain nerve cells aren't quite working right. If one pigment is missing, you will have trouble telling the difference between red and green. Others have trouble seeing blue-yellow. That is a completely different sensing pigment problem. When colorblindness gets really severe, you are only able to determine shades of gray. One out of ten men have some form of colorblindness. It is very rare among women. My reference is Medline Plus.
ReplyDeleteHuntington's Disease is a neurodegenerative genetic disorder that affects muscle coordination and leads to cognitive decline and psychiatric problems. It typically becomes noticeable in mid-adult life. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea, which is why the disease used to be called Huntington's chorea.
ReplyDeleteIt is much more common in people of Western European descent than in those of Asian or African ancestry. The disease is caused by an autosomal dominant mutation in either of an individual's two copies of a gene called Huntington, which means any child of an affected person typically has a 50% chance of inheriting the disease. Through genetic anticipation, the disease may develop earlier in life in each successive generation. About 6% of cases start before the age of 21 years with an akinetic-rigid syndrome; they progress faster and vary slightly. The variant is classified as juvenile, akinetic-rigid or Westphal variant HD.
Genetic testing can be performed at any stage of development, even before the onset of symptoms. This fact raises several ethical debates: the age at which an individual is considered mature enough to choose testing; whether parents have the right to have their children tested; and managing confidentiality and disclosure of test results. Genetic counseling has developed to inform and aid individuals considering genetic testing and has become a model for other genetically dominant diseases.
Raam Reeve
ReplyDeleteSickle cell anemia i when your blood cells are misshapen(like a sickle). This is a genetic disease when you blood cells have an abnormal type of hemoglobin called hemoglobin S. Hemoglobin is the protein that carries oxygen. It is created on chromosome eleven so it is not on the X or Y chromosome therefore an autosomal gene. It is a recessive trait so it is very rare.