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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 ?
|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.