Question

Holandric gene is made up of
(a) 14bp
(b) 1400bp
(c) 14000bp
(d) 140000bp.

Answer 1

Hint: Holandric gene is genes that remains present only on Y chromosome of the sex chromosomes. It is a sex determining chromosome found only in males. It is the one with the smallest number of base pairs.

Complete answer:
Sex-linked genes are the genes that are present on the X and Y chromosomes. The genes located on the X chromosome, whose alleles are absent on the Y chromosome are X-linked genes. Males are hemizygous and females are homozygous or heterozygous for these alleles. The genes located on the Y-chromosome, whose alleles are absent on the X-chromosome are called Y-linked genes or holandric genes. Y gene is the smallest of all genes that occupy only 14 base pairs. Males are hemizygous for these alleles.
- For the determination of sex, in most of the organisms two genes are responsible they are called sex chromosomes or allosomes. Autosomes are the chromosomes that are other than sex chromosomes.
- The two sex chromosomes found in humans are the X chromosome and Y-chromosome. Y-chromosome determines the sex of the offspring.
- If two chromosomes are similar(XX) the individual is described as homogametic and if they are different (XY) or only one sex chromosome(XO) then they are described as heterogametic.
- X-linked and Y- Y-linked genes do not undergo pairing or crossing over during meiosis. The genes which are located on the homologous segments of the X and Y chromosomes are called XY- linked genes.

So, the correct answer is '14bp'.

Note:
-Henking discovered X-chromosome and Stevens and Wilson discovered the Y chromosome. They revealed that the chromosomal basis of sex depended on the presence or absence of the Y-chromosome.
-Y- chromosome is the sex-determining chromosome.