Biology today

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following the rediscovery of Mendel’s work in the early 1900s, research focused on many ways in which genes can influence an ind ...

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incomplete dominance after Mendel, several cases were recorded where f 1 hybrids were not related to either of the parents but e ...

The abO locus controls the type of glycolipids found on the surface of erythrocytes, apparently by specifying the type of glycos ...

Lethal alleles alleles that cause an organism to die when present in homozygous condition are called as lethal alleles. Mutation ...

Example: Complementary genes were first studied by bateson and Punnett (1906) in case of flower colour of sweet pea (Lathyrus od ...

The independent genes do not have cumulative effect. They produce the same phenotype whether present in homozygous or heterozygo ...

epistasis in case of alzheimer’s disease understanding epistatic interactions may be the key to understand complex diseases, suc ...

Table: Summary of Epistatic Ratios Genotypes A–B A–bb aaB– Classical ratio 9 3 3 1 Dominant epistasis 12 3 1 recessive epistasis ...

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Why didn’t Mendel observe linkage? It is quite often said that Mendel was very fortunate not to run into the complication of lin ...

complete linkage Complete linkage is a linkage or grouping of genes on a chromosome Fig.:Cross showing complete linkage which is ...

The size of the linkage group depends upon the size of chromosome. The smaller chromosome will naturally have smaller linkage gr ...

fail to appear in females unless their father also possesses the same and the mother is a carrier. When present in heterozygous ...

Heterozygous females also pass the allele to one-half of their daughters, who become carriers but do not develop the disorder. a ...

characteristics of quantitative inheritance The segregation phenomenon occurs at an indefinitely large number of gene loci. If ...

If n is the number of contributing dominant alleles then the ratio like 1 : 4 : 6 : 4 : 1 or 1 : 6 : 15 : 20 : 15 : 6 : 1 can be ...

Penetrance anD exPreSSivity Genes express themselves by producing visible phenotypic effect. Generally, the structural genes exp ...