To date, the genetic characteristics of organisms that are the subject of research biologists, scientists of the world, are not fully studied.Every day new and interesting facts.With improved technology, analysis methods and modern equipment, the scientists deeper penetrate the mysteries of the chromosomal system, studying her the molecular and supramolecular structure.
Today, however, humanity has achieved a lot in the study of genetics and microbiology.Each interested person opening tutorial can study the structure of chromosomes, their structure and function in vivo.About this talk.By type of chromosome structure divided into:
- telotsentrichnye,
- akrotsentrichnye,
- submetacentic,
- metatsentrichnye.
Telotsentrichnye are rod-shaped and contain a centromere, which originate from the two strands.Akrotsentrichnye also have a rod-like structure, but one "arm" of their small, almost imperceptible.(Shoulder - is part of the chromosome, which comes in one side of the centromere).Submetatsenrichnoe structure is a chromosome with long or short arms.And to metatsentrichnomu type of structure are V-shaped chromosomes that have the same along the length of the shoulders.
Chromosomes bezyadernyh organisms, viruses and bacteria
chromosomes each organism highly individual.The structure of the chromosomes of bacteria, viruses and some types of algae is the simplest.The bacterial chromosome consists of naked double-stranded DNA molecule type which can be linear or annular.The structure of the chromosome apparatus virus is different from the bacterial DNA molecules.For example, the length of the DNA molecule of the virus varies from one to a hundred micrometres, and bacterium DNA molecule reaches a length of two thousand micrometers.Split, that is a subsidiary of the molecule synthesis (replication) of viruses starts chromosomes from one starting point and goes along its entire length, and the bacteria it goes in both directions from the starting point, where the image of two forks split DNA.Chromosome virus comprising the RNA molecule is a single RNA strand form, although there are encountered dvuhnitchatye molecule.The size of these chromosomes are much less than those containing DNA.
nuclear chromosomes of organisms
structure of chromosomes of a eukaryotic cell having a nucleus is considered one of the most difficult.It is based on a linear DNA molecule of considerable length, which can reach 5 cm!These items can be found by studying the structure of the human chromosomes.In addition to the DNA molecule, chromosome make specialized proteins - histones.There were five: H1, H2A, H3, H4 - are the main protein.Apart from these the molecule contains proteins negistonnye.The structure of eukaryotic chromosomes is very difficult and takes the form of beads.
There are several types of chromosomes, which occur less frequently.They include the giant chromosomes, polytene chromosomes and chromosomes lampbrush.
- Giant chromosomes differ huge size.They can be found at certain stages of the cell cycle - the period of life between cell divisions.They are found in cells of certain insect larvae as well as vertebrates and invertebrates.
- polytene chromosomes are multiple child threads that extend from the parent in a large number, but not settling in a chaotic manner, and combined into a single spiral.They are contained in the cells of internal organs of living organisms, for example in intestinal cells, body fat, salivary gland, trachea.Also polytene chromosomes can be found in the vessels of the larvae of two-winged insects.
- lampbrush chromosomes - a giant chromosomes, longer than polytene, which are found in the oocytes (egg cells) of vertebrates.Structure lampbrush chromosomes different lots of different size and length of the side tabs, on which the synthesis of RNA.
As you can see, a lot of types of chromosomes.And in all organisms are different.And most interesting is that this molecular mechanism of the system is still not studied until the end.The structure of the chromosomes, the number, structure, and its violation, leading to mutations organisms - all this is an open topic of geneticists.
