Genetics Past Paper 2022 BS Botany 6th Semester.Genetics Past Paper 2023 All University BS Botany 6th Semester.Genetics Past Paper 2024 All University BS Botany 6th Semester.
Define Penetrance and Explain ?
Penetrance refers to the proportion of people with a particular genetic variant (or gene mutation) who exhibit signs and symptoms of a genetic disorder. If some people with the variant do not develop features of the disorder, the condition is said to have reduced (or incomplete) penetrance.
Difference Between Penetrance and Expressivity ?
|Penetrance is the percentage of individuals with a given phenotype, who exhibit the phenotype associated with that particular genotype||Expressivity is the extent of a given genotype, expressing at the phenotypic level.|
|Penetrance explains how often the gene is expressed.||Expressivity explains the extent of gene expression.|
|Penetrance is a quantitative measurement.||Expressivity is a qualitative measurement.|
|Penetrance explains whether the disease shows up.||Expressivity explains how a disease shows up.|
|Penetrance describes the expression of a single gene.||Expressivity describes the expression of a group of characters or a syndrome.|
|Incomplete penetrance is a phenomenon that makes genetic analysis more difficult.||Variable expressivity is a phenomenon that makes genetic analysis more difficult.|
|The expression of BRCA1 and BRCA2 genes develop cancers in some individuals but not in others as a result of penetrance.||The characteristics of Marfan syndrome widely vary among individuals as a result of expressivity.|
Difference Between Test Cross and Back Cross ?
|Test cross||Back cross|
|Breeding of the dominant phenotype with the homozygous recessive phenotype (parent) is known as a test cross.||The breeding of F1 generation with one of its parent plants is known as a back cross.|
|All test crosses are backcrosses.||A backcross can be said as a test cross if the parent is recessive.|
|The F1 hybrid is crossed with a recessive genotype.||An F1 hybrid is crossed with either homozygous dominant or heterozygous genotypes.|
|The test cross helps in the identification of the genotype of the dominant individual.||The back cross helps in the identification of the elite genotype by checking the segregation of genes at the time of gamete formation.|