What are chromatids and centromere?

Chromosomes are the long, thin thread like structure found inside the nucleus of a cell containing genes inside it.

Chromosomes are located inside the nucleus of a cell.

The different types of chromosomes are:
        - Meta centric.
        - Sub-metacentric.
        - Acrocentric.
        - Telocentric.

The literal meaning of chromosomes are:
Chrome:     color.
Soma:     body.

Chromosome are made of the gentle material DNA and protein.
A gene is the segment of DNA which can form exact copies by the process of replication.
It is located in chromosomes.

Metacentric chromosomes are the chrosomes in which the centromere is located at the center dividing the chromatids into two halves.

Acrocentric chromosomes are the chrosomes in which the centromere is located away from the center.
Telecentre chromosomes are the chrosomes in which the centromere is located at the end of chromatids.

The somatic cells that contains the diploid number of chromosomes is called diploid cells. The number of chromosome in the diploid cell of a gorilla, pine and frog are:
        Gorilla: 24
        Pine: 12
        Frog: 13

The gametes cell that contains haploid number of chromosomes is called haploid cell.

Any 3 functions of chromosomes are:
        - It acts as a hereditary vehicles.
        - It control protein synthesis, cell growth and cell-repair.
        - It forms link between parents and their off-springs.

The chromosomes that carry gene for the sexual characters called sex chromosomes.
Chromosome of this type is different from autosomes is that autosomes determines various characteristics of the body where as sex chromosomes determines sex of an individual.

Sex chromosomes are responsible for the determination of sex in human body. Sex is determined by the genetic inheritance. Sex chromosomes  that carries genes for male characters are Y and female Y. So,

A disorder that occurs in the human body due to the increase or decrease in the number of chromosomes is called chromosomal disorder.
Any 3 examples are:
        - Down's syndrome.
        - Klinefelter's syndrome.
        - Turner's Syndrome.

Down's Syndrome is a genetic disorder caused by the presence of all or part of an extra chromosomes.
Its major symptoms are:
        - Difficulties in physical activities.
        - Slanting eyes and small ears.
        - Short sightedness.
        - Congenital heart defects.

Kilenfelter syndrome is a genetic disorder caused due to the increase in sex chromosome in male
Its major symptoms are:
        - Tendency to loose chest hair.
        - Poor beard growth.
        - Breast development.
        - Small tastes.
        - Frontal baldness absent.

Turner's syndrome is a chromosomal disorder occurred in female due to the decrease of sex chrosomes.
Its major symptoms are:
        - Swelling of hands & feet of newborn baby.
        - Broad chest.
        - Low-set ears.
        - Obesity.
        - Poorly developed ovaries.

Turner's syndrome occurs due to the lack of x chromosome in female.