Chromosomes function: introduction
Chromosomes are present in the nucleus and are thread-like objects. They are made of DNA and carry genes which are passed on from one generation to another.
Chromosomes were first described by Strausberger in 1875, but he was not the one to use the term. The term was later used by Waldeyer in 1888. The word itself originates from two words – one “chromo”, which means colour and the other “soma”, which means body.
As a general rule all creatures of a certain species have exactly the same number of chromosomes. And other species which are similar to one another tend to also have the same number.
Species which have one set of chromosome, such as gametes, are said to have a haploid number of chromosomes. Those which have two sets are said to have diploid number. Consequently - triploids, tetraploids, etc.
Chromosomes function: numbers
Humans have 46 chromosomes. Chimps are very close to us with 48 of them. Dogs or chicken
But it is not only “traditional” living creatures which have chromosomes. Information is passed on in plant life as well. Onions, for example, have 16 chromosomes and tobacco has as many as the chimp – 48.
The number of chromosomes that we have observed so far ranges from 2 (round worm) until 300 (Protozoa). But naturally these are the extremes, so most data is observed in the 12-50 range.
It is also interesting that organisms with a low number of chromosomes and especially plants tend to have longer “thread” chromosomes. So as you see, chromosomes also vary in size and shape.
Chromosomes function: process
Chromosomes are capable of self duplication. During this process the DNA strands unwind from one another and start forming each their own new strands. As a result the original two wound strands separate and duplicate forming two new DNA strands where each one has one old strand and one new strand.
Chromosomes also help in the expression of characters in an organism. They do this by synthesizing proteins in cells, which consequently bring a certain character. This is useful in order to transmit information from one generation to another, i.e. from the parent to the child.
The chromosomes also control the physiological and biochemical processes in the body of the organism.