humans chromosomes

In the diploid number, chromosomes are always found in pairs. In each pair there are two identical chromosomes, called homologous chromosomes. These chromosomes are identical in size, appearance and position of the centromere. Apart from this, the two homolog..

As can be seen from the human karyogram, the chromosomes are classified into two types, autosomes and sex chromosomes. The autosomes have homologous chromosomes as pairs whereas the sex chromosomes are of two different types - X and Y. A female has..

It is a comprehensive international effort started in 1990 by molecular biologists to map the entire human genome by determining the complete nucleotide sequence of DNA of each chromosome..

>Culturing of human cells invitro, help in understanding the biochemical basis of inheritance. Human cytology and karyotyping helps in ascertaining the number, shape size and structural features of chromosomes. Study of monogygotic twins helps in distinguishing between..

Cell division is a method by which new cells are originated from pre-existing cells. The formation of daughter amoebae in amoeba, the development of sex cells and the growth of a young animal or plant into an adult, all involve cell multiplication. In order to multiply in number, cells undergo cell..

All the genes located on a particular chromosome, form a linkage group. Since the genes present on a particular chromosome have their alleles located on its homologous chromosome, genes on a pair of homologous chromosomes. Hence, the number of linkage groups ..

During the formation of gametes, the females will have only one type of gametes, all with one X chromosome. However, the males will produce two types of gametes or sperms, half with X chromosome and half with Y chromosome. Thus the sex of a zygote is determined by whic..

This type of sex determination occurs in insects and mammals including human beings. Here, the females have two identical homologous sex chromosomes designated as XX and the males have two dissimilar sex chromosomes designated as X and Y. Thus, females are homogametic,..

Chromosome number is a species-specific character. The complete set of chromosomes in the body cell of a species is known as karyotype. For example, the 23 pairs of chromosomes found in the somatic cells represent the human karyotype. In the karyotype it is p..

These disorders are caused by genes present on the sex chromosomes. The abnormal disorders express more commonly in males than females. Some common examples are colour blindness, haemophilia and congenital night blindness. fig. 20.5 Colour Blindn..