DEFINITION, STRUCTURE AND FUNCTION OF RNA
Welcome to the Science Lovers, a simple blog to
share knowledge with full sincerity. This time we will share knowledge about
RNA, some of the main topics that will be discussed is the definition of RNA,
RNA Structure, Function and Mechanism of RNA, and RNA formation process.
Hopefully his knowledge can be useful.
A. DEFINITIONS RNA
As well as DNA (deoxyribonucleic acid), RNA
(ribonucleic acid) is also a nucleic acid (polynucleotide comprising units
mononucleotide). It's just different from the DNA units builders
dioksinukleotida so-called double-stranded, RNA is single-stranded nucleic acid
consisting of units builders in the form of mononucleotide. Each nucleotide
consists of a phosphate group, a pentose group and a base group Nitrogen (N).
RNA is the result of transcription of a DNA
fragment, RNA so that the position is as polymers and is much shorter than DNA.
Unlike DNA is usually found in the nucleus of the cell, the RNA is mostly
located in the cytoplasm, especially in the ribosome.
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B. RNA STRUCTURE
As nucleic acid, RNA molecules have different
structures with DNA. RNA is a single chain-shaped ribbon and twisting. Each
chain RNA is a polynucleotide consisting of many ribonucleotide. Each
ribonucleotide molecule consists of three groups, namely
1. Cluster pentose (ribose sugar);
2. Cluster phosphate, and
3. Bases nitrogen.
Nitrogenous base can be divided into two types,
of which include:
- Purine bases are the same as the structure of DNA, consisting of adenine (A) and Guanine (G);
- Pyrimidine bases are different from the DNA that is composed of Cytosine (S) and Urasi (U).
RNA has a molecular
weight of between 25,000 to several million. Although basically, RNA contains a
single polynucleotide chains, but the chains are commonly folded to form a double
helix region containing base pairs A: U and G: C.
With the bonding
between purine and pyrimidine bases with groups such pentose sugar ribose
formed nucleoside or ribonucleoside. Ribonucleoside which binds with phosphate
groups to form a nucleotide or ribonucleotide.
C.
FUNCTIONS AND MECHANISM RNA
In general, the RNA
serves as a store of information. However, the main role of RNA and applies to
all living things is as an intermediary between DNA and protein in the process
of genetic expression. In carrying out that role, produced as an RNA copy of a
DNA sequence code nitrogenous bases in DNA transcription stage. Code base
sequences are arranged in the form of triplets (three base sequences nitrogen),
known as codons. Each codon is related to an amino acid monomers that make up
proteins whose purpose ie, as a code to stop.
If the review is
based classification, every kind of RNA has more specific functions by a
different mechanism and interrelated. The two divisions, namely:
1. RNA genetic
RNA genetic take a
share of the work as DNA and owned only by certain living organisms that do not
have DNA, such as some types of viruses. Inside the host cell, the RNA found in
viruses will undergo reverse transcription into RNA-DNA genetic code that
eventually form the DNA. Then the viral DNA will go into the nucleus of the
host and insert kedalamya so on awlanya will damage the host DNA and form the
mRNA. This mRNA translation will have to produce the viral coat proteins
forming new viruses. The important role of these molecules is to bring all the
genetic material, such as those held by the DNA.
2. The non-genetic
RNA
Non-genetic RNA is a
molecule which is owned by the genetic material of living creatures governed by
DNA. This class of living creatures within the cell DNA and RNA. In other
words, its role is not like DNA. Based on the location and function, non-genetic
RNA is divided into three types, including:
a. Messenger RNA
(mRNA)
Other terms mRNA
known as messenger RNA (RNAd) which has a single-chain RNA long enough. mRNA is
formed by the DNA within the nucleus of the cell (nucleus) and is one of the
RNA sequence of its base pairs with one of the base sequence of the DNA chain.
The role of mRNA in the form of a linear single band is delivering genetic
information to the cell nucleus to the ribosomes in the cytoplasm into the mold
pattern to determine the specificity of the amino acid sequence in the
polypeptide chain. The sequence in the chain of amino acids that make up the
polypeptide chain in accordance with codon sequences (genetic code) of the mRNA
molecules concerned. mRNA is only created when needed which will then be
destroyed in the plasma if the task has been completed.
b. Ribosomal RNA
(rRNA)
Ribosmal RNA formed
by DNA and is a major component contained in the ribosome, which reached 30-46
and 70-80% protein. RRNA molecules form a single tape, unbranched, and
flexible. Ribosomal RNA is the main site for building proteins. rRNA carries
enzymes needed for protein synthesis. This enzyme is known ribosim.
c. Transfer RNA
(tRNA)
Transfer RNA formed
by the DNA in the cell nucleus (nucleus), but put himself in the cytoplasm.
tRNA is the shortest RNA molecules that transport amino acids one by one to the
ribosomes so that it can interpret the genetic message in a series of codons
along an mRNA molecule. The transport of amino acids in accordance with the code
contained in RNAd which will be instrumental in the process of protein
synthesis. This process can occur as a result of the attachment of an amino
acid to the tRNA opposite end with the end of the anticodon (short circuit
located on one end of the tRNA).
D. PROCESS OF THE FORMATION OF RNA
The process of the
formation of RNA is closely related to the function of DNA. As with our
previous discussion regarding the definition of which is the result of
transcription of RNA from a DNA fragment. In other words, DNA plays an
important role in the stages of the formation of RNA carries genetic
information in the form of the form of codes or the genetic code in the DNA
double-stranded RNA for the printed form. The process of formation of RNA
consists of two phases * with the help of the enzyme RNA polymerase (RNAp).
These enzymes speed up the process of the formation of RNA. RNA formation
stages include:
1. Transcription
In the transcription
phase, using DNA as a mold disistesis messenger RNA. This process consists of
three stages, namely:
a. Initiation
At this stage, the
enzyme RNA polymerase gene copy, leading to binding RNAp with the promoter (the
meeting place between genes / DNA with RNAp) which will provide transcription
initiation. Furthermore, RNAp will open the double helix of DNA
(double-stranded) that serves as a template that sense chain.
b. Elongation
Here, RNAp will move
along the DNA double strand, open the double helix and assemble ribonucleotides
to the 3 'end of ribonucleotide growing, so the resulting RNA chain which
contains the base sequence of the first nitrogen as a result of recording. If
the results of the recording has reached 30 units, a chemical compound that
acts as a cover for signaling initiation of translation stage, and prevent
degradation of RNA binds to the 5 'end of RNA.
c. Termination
Termination process
is the cessation of the recording process and a new DNA molecule separate from
the DNA template. This stage is characterized by enzyme terdiasosiasinya RNAp
of DNA and RNA is released to produce a complete transcription product called
messenger RNA (mRNA).
2. Translating
Translation is a
translation stage some triplet / codon on the mRNA into amino acids that
eventually form the protein. Each triplet consists of a different sequence of
nitrogenous bases that will be translated into a different amino acid. The
amino acids will produce a specific polypeptide chain to form a specific
protein anyway. Translation process can be:
a. Iniatiation
This phase begins
with the introduction of AUG codon located at the end of the mRNA are called
codons Start. AUG codons would encode the formation of methionine. Furthermore,
methionine is carried by the tRNA to join through bond formation in the large
subunit of the ribosome, forming a complete ribosome. The first tRNA molecules
bound to the ribosome will occupy a special place, namely the P (polypeptides)
that will form a chain which is known by the term polypeptide. While the next
tRNA binds to the second codon and will occupy the ribosomes on the side A
(amino acids)
b. Elongation
This stage is
characterized by activation of the amino acid to each tRNA codon into a codon
that will produce a new amino acids one by satu.Proses engolasi this makes
growing polypeptide chain of amino acids due to the longer growing.
c. Termination
This process was
marked by a meeting between the anticodon carried by tRNA with UAA, UAG, or
UGA, causing cessation of the translational process. Akibanya, terlepaslah
polypeptide chain formed from the ribosome and processed to form a functional
protein.
Now that the
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