But what is DNA?
It is a molecule made up of two “chains” (of genetic information) that intertwine with each other to create a double helix structure.
Each chain has a central part made up of sugars (deoxyribose) and phosphate. Attached to each sugar there are: adenine (A), cytosine (C), guanine (G), and thymine (T) , as the four bases of the chains.
Both chains remain united thanks to the links at their bases; adenine binds thymine, and cytosine binds guanine. The RNA and proteins are formed by instructions in the sequence of bases.
The code that DNA contains is similar in all living things . It is in this set of instructions that the form and functions that an individual must or have are “written”.
In a species, instructions are “added” over the years, all according to various factors to which it has been subjected within evolution.
The fundamental function of DNA is to transmit to descendants all the information necessary to form and have characteristics similar to those of their parents.
Before a cell divides, DNA generates a copy of itself so that the new cell contains the entire genetic code. To do this, the chains are “spread” and “stretched.”
Every organism has two types of cells: eukaryotic and prokaryotic . One of the differences between them is that, while eukaryotes have a cell nucleus where all the genetic material is, prokaryotes, which lack a defined nucleus, have DNA dispersed in the cytoplasm.
Chromosomes are organized units that contain DNA and proteins . These are found in cells and are the structures with the highest genetic load of any living being.
The human being has 46 chromosomes arranged in 23 pairs , of which 22 are autosomes and one pair is sexual. A woman will have an XX sex chromosome pair and a man will have an XY pair. Each species has a fixed chromosome number.
For each chromosome there are two DNA molecules (sister chromatids) linked by the centromere. As we mentioned before, DNA is made up of two chains made up of nucleotides. In each chain there is a nucleotide composed of sugars or deoxyribose, a phosphate group and a nitrogenous base: adenine (A), thymine (T), cytosine (C), and guanine (G), limes A and T complement each other, as well as C and G.
Graphically, DNA resembles a spiral staircase, where its sides are the phosphate group and sugars while the stairs would be nitrogenous bases.
DNA structure examples