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Hematology. Sickle cell trait describes a condition in which a person has one abnormal allele of the hemoglobin beta gene (is heterozygous), but does not display the severe symptoms of sickle cell disease that occur in a person who has two copies of that allele (is homozygous). Those who are heterozygous for the sickle cell allele produce both ...
114,800 (2015) [8] Sickle cell disease (SCD), also simply called sickle cell, is a group of hemoglobin-related blood disorders typically inherited. [2] The most common type is known as sickle cell anemia. [2] It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. [2]
Mendelian traits in humans. A 50/50 chance of inheritance. Sickle-cell disease is inherited in the autosomal recessive pattern. When both parents have sickle-cell trait (carrier), a child has a 25% chance of sickle-cell disease (red icon), 25% do not carry any sickle-cell alleles (blue icon), and 50% have the heterozygous (carrier) condition. [1]
The Punnett square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach in 1905. [3][4][5][6][7][8] The diagram is used by biologists to determine the probability of an offspring having a particular genotype.
Each has one allele for purple and one allele for white. In the offspring, in the F 2-plants in the Punnett-square, three combinations are possible. The genotypic ratio is 1 BB : 2 Bb : 1 bb. But the phenotypic ratio of plants with purple blossoms to those with white blossoms is 3 : 1 due to the dominance of the allele for purple.
In medical genetics, compound heterozygosity is the condition of having two or more heterogeneous recessive alleles at a particular locus that can cause genetic disease in a heterozygous state; that is, an organism is a compound heterozygote when it has two recessive alleles for the same gene, but with those two alleles being different from each other (for example, both alleles might be ...
When conducting a dihybrid test cross, two dominant phenotypic characteristics are selected and crossed with parents displaying double recessive traits. The phenotypic characteristics of the F1 generation are then analyzed. In such a test cross, if the individual being tested is heterozygous, a phenotypic ratio of 1:1:1:1 is typically observed. [7]
Males are more likely to inherit red–green color blindness than females, because the genes for the relevant opsins are on the X chromosome. [1] Screening for congenital red–green color blindness is typically performed with the Ishihara or similar color vision test. [1] It is a lifelong condition, and has no known cure or treatment. [1]