Genetics and Plant Breeding

The identical twins will have the same base sequencing in their DNA because they originates from the same egg and sperm of the parents.

He gave us the basis for understanding genetic inheritance in all living things, including humans. His realization that we inherit units or genes was the key to it.

Mendel called genes as factors. In all the individuals, each inherited trait is determined by at least one gene from each parent.

An allele is an alternate form of a gene. If an individual is homozygous (YY or GG) for a trait, it has inherited the same allele from both parents. If it is heterozygous (YG), it has inherited different alleles for the trait.

This is a definition of principle of independent assortment. Stated in other words, the genes that determine a trait assort independently of the genes for other traits. As a result, new combinations of genes, present in neither parent, are possible.

Phenotype is the observable characteristic, including physical appearance. It results from the genotype and environmental influences. A phenotype includes not only easily measured traits like hair colour but also less apparent ones such as blood type.

In most cases, these alleles are totally responsible for determining blood type phenotypes. The inheritance usually follows simple Mendelian patterns.

Because of the Bombay Phenotype and other possible exceptions, the ABO blood type system is not conclusive in determining whether or not someone could be a parent of a particular child.

The rules of dominance for the ABO system are that A and B are both dominant over O (i.e. O is recessive) and A and B are co-dominant.

The Rh blood factor is a dominant trait. Therefore, both DD and Dd people have the Rh antigen on the surface of their red cells which makes them Rh positive.

Homozygous recessive is defined as a diploid carrying two copies of the recessive allele of the examined gene. Since the ability to taste PTC is a dominant allele, therefore this genotype will be least expressed by this person.

Out of total progenies, 25 % will have O blood group. When both parents have blood types BO, then it is possible that they can produce a child of O blood group.

Since white flowers are the recessive traits in Pisum sativum, the genotype of the parents would be pp x pp, where P= gene for a purple flower and p= gene for a white flower. Because it is a recessive trait, both white flowered parents must be homozygous recessive. Therefore, all of their offsprings will also have white flowers, because that is the only gene available.

The output of the genes is the phenotypic character which physically observed. Eye colour, skin colour, hair colour, earlobe shape, etc. are all phenotypic traits of an individual.

In the above question one parent is homozygous recessive, pp, while the other is heterozygous, Pp. With the help of Punnett square, you can see that half of the offspring will be homozygous, thus purple, and half will be white.