Gene: A gene is a region of DNA which is made up of nucleotides and is the molecular unit of heredity.The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits.
Allele: Every gene has two alternative forms for a character producing different effects. These alternative forms of a gene are called allele and are present in the same position on homologous chromosomes.
Autosomes: Autosomes or somatic chromosomes carry genes which determine the somatic characteristics and do not have any influence on determining the sex of the organism. They are homologous by nature.
Allosomes: Allosomes are sex chromosomes which carry genes responsible for sexual characteristics and as such have a significant role in the determination of sex. They may be homologous (XX) in the case of females and heterologous (XY) in the case of males.
Haploid cells: Haploid describes a cell that contains a single set of chromosomes. The term haploid can also refer to the number of chromosomes in egg or sperm cells, which are also called gametes.
Diploid cells: Most mammals are diploid organisms, which means they have two homologous copies of each chromosome in the cells. In humans, there are 46 chromosomes. In most diploid organisms, every cell except for gametes will be diploid and contain both sets of chromosomes.
Criss cross inheritance: The genes which are located on X chromosome (sex chromosome) are called sex-linked genes. These genes show criss-cross inheritance.
Genetics is a branch of biology that studies inheritance and variations. Inheritance is the process of passing characters from parents to offspring. Variation, on the other hand, is the degree by which an offspring differs from its parents.