DNA is vital for all
living beings – even plants. It is important for inheritance, coding for
proteins and the genetic instruction guide for life and its processes. DNA
holds the instructions for an organism's or each cell’s development and
reproduction and ultimately death.
Proteins
A protein is a
complex molecule found in the body that is abundant and is vital for most
living functions.
There are many
different types of proteins that include structural proteins, messenger
proteins, enzymes and hormones. These perform various functions from forming
the organs, skin and bones and the body to performing actions and functions via
messengers, enzymes and hormones.
How is DNA linked to
proteins?
DNA carries the codes
for proteins. However, the actual protein differs a lot from the codes present
on the DNA. The basic steps include:
Transcription
The first step that
occurs is a process known as transcription. Here the information on the DNA is
written down onto a different molecule called the RNA. This molecule acts as a
messenger to carry the information to other parts of the cell.
Translation
The next step is
called translation. In this step the cell organelles called ribosomes come into
play. These ribosomes act as translators by translating the messenger's code
into the proper protein format or a chain of amino acids that form the building
blocks of the protein. Each amino acid is formed by combining three bases on
the RNA.
Modification and
folding
The third step is
modification and folding and structuring of the final protein and sending it to
the required areas in the body.
Coding for proteins
DNA is read by the
messengers that break it open into single stranded polynucleotide chains and is
copied into RNA.
RNA forms opposite
bases from that present on the DNA. For example, G on the DNA forms C on the
RNA strand.
Each of the bases
gets together in threes and these form particular amino acids. There are 20
such amino acids. These are also known as the building blocks of proteins.
The amino acids first
form a long chain called the polypeptide chain. This polypeptide chain
undergoes conformational and structural changes and folds and refolds over
itself to form the final complex structure of the protein.
DNA replication
Apart from coding for
proteins, DNA also replicates. This helps in a variety of functions including
reproduction to maintenance and growth of cells, tissues and body systems.
In this process the
DNA strands, that are tightly wound with each other, unwind and literally unzip
to leave several bases without their partners on the other strand and remain
along the backbone of the molecule.
The bases are very
specific about which base they will attach to and the adenine only pairs with
thymine and guanine will only pair with cytosine. Unpaired bases come and
attach to these free bases and a new strand is formed that is complementary to
the original sequence.
The end result is a
strand that is a perfect match to the original one prior to it unzipping. This
result in two new pairs of strands and two coiled DNA. Each of the new DNA
contains one strand from the mother pair and a new one.
DNA inheritance
DNA is important in
terms of heredity. It packs in all the genetic information and passes it on to
the next generation. The basis for this lies in the fact that DNA makes genes
and genes make chromosomes.
Humans have 23 pairs
of chromosomes – a total of 46 chromosomes. Twenty-two of these pairs, called
autosomes, look the same in both males and females. The 23rd pair is called the
sex chromosomes and differs between males and females. Females have two copies
of the X chromosome or XX, while males have one X and one Y chromosome.
Both parents have
reproductive cells – sperms in fathers and ovum or eggs in mothers. These
sperms and eggs contain half the number of chromosomes – 23 each. When the egg
and the sperm fertilizes, this gives rise to a cell that has the complete set.
Thus a person inherits half of his or her genes from each of the parents.
Source"http://www.news-medical.net/life-sciences/DNA-Biological-Functions.aspx"
Source"http://www.news-medical.net/life-sciences/DNA-Biological-Functions.aspx"
