Lecture 5 : Mutation ; Genetic disorder: pedigree analysis ; Mendelian disorder ; Chromosomal Disorders

Discuss in detail the contributions of Morgan and Sturvant in the area
of genetics.

A normal visioned woman, whose father is colour blind, marries a normal
visioned man. What would be probability of her sons and daughters to
be colour blind? Explain with the help of a pedigree chart.

a. In humans, males are heterogametic and females are homogametic.
Explain. Are there any examples where males are homogametic
and females heterogametic?
b. Also describe as to, who determines the sex of an unborn child?
Mention whether temperature has a role in sex determination.

In a plant tallness is dominant over dwarfness and red flower is dominant
over white. Starting with the parents work out a dihybrid cross. What is
standard dihybrid ratio? Do you think the values would deviate if the
two genes in question are interacting with each other?

It is said, that the harmful alleles get eliminated from population over a
period of time, yet sickle cell anaemia is persisting in human population.
Why?

How do genes and chromosomes share similarity from the point of view
of genetical studies?

Why is the frequency of red-green colour blindness is many times higher
in males than that in the females?

In peas, tallness is dominant over dwarfness, and red colour of flowers
is dominant over the white colour. When a tall plant bearing red flowers
was pollinated with a dwarf plant bearing white flowers, the different
phenotypic groups were obtained in the progeny in numbers mentioned
against them:
Tall, Red = 138
Tall, White = 132
Dwarf, Red = 136
Dwarf, White = 128

How was it concluded that genes are located on chromosomes?

What is Down’s syndrome? Give its symptoms and cause. Why is it that
the chances of having a child with Down’s syndrome increases if the age
of the mother exceeds forty years?

Can a child have blood group O if his parents have blood group ‘A’ and
‘B’. Explain.

In a Mendelian monohybrid cross, the F2 generation shows identical
genotypic and phenotypic ratios. What does it tell us about the nature
of alleles involved? Justify your answer.

How does a mutagen induce mutation? Explain with example.

In a monohybrid cross of plants with red and white flowered plants,
Mendel got only red flowered plants. On self-pollinating these F1 plants
got both red and white flowered plants in 3:1 ratio. Explain the basis
of using RR and rr symbols to represent the genotype of plants of
parental generation.

Identify the sex of organism as male or female in which the sex
chromosome are found as
(i) ZW in bird (ii) XY in Drosophila (iii) ZZ in birds. (iv) XO in grasshopper.

A haemophilic man marries a normal homozygous woman. What is the
probability that their daughter will be haemophilic?

How sex is determined in human brings?

Give any two similarities between behavior of genes (Mendel’s factor)
during inheritance & chromosomes during cell division.

What is meant by aneuploidy?

Who had proposed the chromosomal theory of inheritance?

Define and design a test - cross?

Explain the Law of Dominance using a monohybrid cross.