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One example is hearing impairment. Hearing impairment was tracked in one specific family and through seven generations all males were affected by this trait. However, this trait occurs rarely and has not been entirely resolved. [9] Y-chromosome deletions are a frequent genetic cause of male infertility.
Analysis of the pedigree using the principles of Mendelian inheritance can determine whether a trait has a dominant or recessive pattern of inheritance. Pedigrees are often constructed after a family member afflicted with a genetic disorder has been identified. This individual, known as the proband, is indicated on the pedigree by an arrow. [5]
These tables can be used to examine the genotypical outcome probabilities of the offspring of a single trait (allele), or when crossing multiple traits from the parents. The Punnett square is a visual representation of Mendelian inheritance, a fundamental concept in genetics discovered by Gregor Mendel. [10]
Three different types of genetic selection. On each graph, the x-axis variable is the type of phenotypic trait and the y-axis variable is the amount of organisms. Group A is the original population and Group B is the population after selection. Top (Graph 1) represents directional selection with one extreme favored.
Autosomal dominant 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]
Genetic linkage is the tendency of DNA sequences that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction.Two genetic markers that are physically near to each other are unlikely to be separated onto different chromatids during chromosomal crossover, and are therefore said to be more linked than markers that are far apart.
In biology, a cline is a measurable gradient in a single characteristic (or biological trait) of a species across its geographical range. [1] Clines usually have a genetic (e.g. allele frequency, blood type), or phenotypic (e.g. body size, skin pigmentation) character. They can show either smooth, continuous gradation in a character, or more ...
An example of a family pedigree displaying an autosomal recessive trait. A pedigree is a diagram showing the ancestral relationships and transmission of genetic traits over several generations in a family. Square symbols are almost always used to represent males, whilst circles are used for females.