Slide 1 : Apt Academic Solutions
Slide 2 : GENETIC BASIS OF INHERITANCE Apt Academic Solutions
Slide 3 : Apt Academic Solutions
: Session objectives Apt Academic Solutions
Slide 5 : Warm up ! At which stage is the fate of genetic constitution of gametes finally decided?
Metaphase I
Anaphase I
Anaphase II
Interphase Apt Academic Solutions
Slide 6 : Mendel – Father of genetics Apt Academic Solutions
Slide 7 : Mendel’s Experiments Apt Academic Solutions
Slide 8 : Mendel’s Experiments Apt Academic Solutions
Slide 9 : F1 Generation F2 Generation Apt Academic Solutions
Exception to Law of Dominance : Exception to Law of Dominance Incomplete Dominance Co Dominance In both cases, genotypic & phenotypic ratio is 1:2:1 Apt Academic Solutions
Class Exercise : Class Exercise Which of the following crosses would produce a genotypic ratio of 1:2:1 in F2?
AB x AB
Ab x Ab
Ab x ab
none Apt Academic Solutions
Class Exercise : Class Exercise Gene B produces black coat color in cat which is dominant over white coat (b). Progeny of a black & white produces 3 offspring – 2 black & 1 white. Genotype of the parents are
BB & bb
Bb & bb
Bb & Bb
Data insufficient Apt Academic Solutions
Multiple alleles : Multiple alleles Gene can exists in more than two alternative forms (allele)
All forms of gene / allele always occupy the same locus It is an exception to the Mendellian hypothesis of concept of unit factor No. of genotypic class for multiple allele = n(n+1)/2 Apt Academic Solutions
Multiple Alleles : Multiple Alleles Codominance
Alleles IA and IB of human blood groups Relation among alleles are
(IA = IB) > i Apt Academic Solutions
Lethal Gene : Lethal Gene F2 genotypic & phenotypic ratio for dominant lethal gene is 2:1 F2 genotypic ratio for recessive lethal gene is 1:2 & there is NO phenotypic ratio Apt Academic Solutions
Slide 16 : Mendel’s Dihybrid Cross Apt Academic Solutions
Class Exercise : Class Exercise 9. Heterozygous tall (Tt) and dwarf (tt) Pea plants are crossed. The ratio in the offspring shall be
all tall
1 tall : 1 dwarf
3 tall : 1 dwarf
None of these Apt Academic Solutions
Class Exercise : Class Exercise 10. A pure tall plant is reared in a soil poor in nutrition and reached the size of dwarf plant. If this plant is selfed, the phenotype in the F1 generation is most likely to be
all tall plants
all dwarf plants
50% tall and 50% dwarf
25% tall and 75% dwarf Apt Academic Solutions
Slide 19 : Apt Academic Solutions