Question

What is meant by chromosomes. Explain its types.

Answer 1

Hint: There are 46 chromosomes found in humans, among them 44 chromosomes are related to phenotypic inheritance only 2 chromosomes are involved in genotypic inheritance.

Complete Answer:
- We all have heard about the word chromosome that carries the genetic information of any organisms. Let’s understand about the chromosome in detail; the chromosome is a thread-like structure that is found in the nucleus of an organism. It is made up of protein and single deoxyribonucleic acid molecules.
- The DNA consists of specific information that makes every living organism different and is passed from parents to the offspring. The chromosome is divided into three parts like; pellicle, matrix, and chromonemata.
- The pellicle is the outer surface around the substance and it is thin in shape formed from achromatic substances. The matrix is the substance that contains the chromonemata and is formed from non-genic materials, and the chromonemata consists of spirally coiled thread that are tightly packed, it consists of 8 microfibrils that formed from double helix of DNA.
- The chromosome helps to determine the sex of the offspring in humans by sex determination. Sex determination is a system through which the sexuality of the offspring is determined, whether it is a male offspring or female.
- Mostly chromosomal sex determination is being used to determine the sex of an offspring. To understand the chromosomal sex determination we should know that in humans, we have 23 pairs of chromosomes, among these 22 pairs are autosomes while one pair is termed as sex chromosome. This one pair helps in determining the sex of an individual.
- In humans females have 2X chromosomes that they received from each parent and males have one X and one Y chromosomes that they receive from each of the parents. Therefore, it is the father who is responsible for the sex of the child not the mother.
- Now, there are four types of chromosome are there; metacentric, submetacentric, afrocentric, and telocentric. Metacentric chromosomes mean the centromeres in the centre and divide the sections equally. The submetacentric chromosome means the centromeres are found slightly away from the centre. Acrocentric chromosome means the centromeres is found severely off-set from the centre, and telocentric chromosome means the centromeres is found in the end of the chromosome.

Note: Any abnormality in the sex chromosome causes sexual disorders like monosomy that is missing of whole sex chromosome, trisomy inclusion of one extra chromosome. Klinfelter’s syndrome and Turner’s syndrome are the sexual disorders cause due to addition and deletion of sex chromosomes.