Incomplete Dominance Video Lecture - NEET

incomplete dominance the trend of
recessive characters disappearing in
first generation and then reappearing in
next generation was perfect
till the experiments were performed on
pea plant but using other traits in
other plants led to failure of
applicability of law of dominance in
some cases such a deviation from law of
dominance was called as incomplete
dominance when neither of the alleles of
a character is completely dominant over
the other and the f1 hybrid is
intermediate between the two parents the
phenomena is called incomplete dominance
the inheritance of flower color in the
dog flower Snapdragon or anti Raynham SP
is a good example to understand
incomplete dominance in a cross between
true breeding red flower capital R R and
true breeding white flower plants small
R R the f1 capital R small R was pink
when the f1 was self pollinated the f2
resulted in the following ratio 1
capital R R red is 2 to capital R small
R pink is to 1 small R are white here
appearance of pink flower seemed as of
the two homozygous conditions were
blended together like plant in the cross
capital R was not completely dominant
over small R and this made it possible
to distinguish capital R small R as pink
from capital R R red and small R are
white in this case the actual flower
color phenotype probably results from
varying amounts of production of the red
pigment the homozygous red
produces a lot of the pigment the
homozygous white plant produces none of
the pigment and the heterozygote
produces half as much as the homozygous
red when chickens with splashed white
feathers are crossed with black
feathered birds their offspring are all
slate blue when blue chickens are
crossed among themselves they produce
splashed white blue and black offspring
and the ratio of 1 is to 2 is to 1 due
to incomplete dominance this dominance
and recessive traits can be best
understood when we know what exactly a
gene does every gene contains the
information to express a particular
trait in a diploid organism there are
two copies of each gene that is as a
pair of alleles now these two alleles
may not be similar as in heterozygotes
one of these alleles may have undergone
some changes which modifies the
information that particular allele
contains let us take an example of a
gene that contains the information for
producing an enzyme they will be two
allelic forms responsible for production
of the enzyme let us assume the normal
allele produces the normal enzyme but
the modified allele could be responsible
for production of the normal less
efficient enzyme or a non-functional
enzyme or no enzyme at all