DNA and RNA: Definition, Characteristics, Differences and Discussion of the Process

DNA and RNA: Definition, Characteristics, Differences and Discussion of the Process – What is the meaning and difference between DNA and RNA? On this occasion About the knowledge.co.id will discuss it and of course other things that also cover it.

Let's look at the discussion together in the article below to better understand it.

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DNA and RNA: Definition, Characteristics, Differences and Discussion of the Process

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DNA (Deoxyribonucleic Acid) or deoxyribonucleic acid (ADN) is a type of biomolecule that stores instructions – the genetic instructions of each organism and many types of viruses are nucleic acids that are inside the living cells life. Meanwhile, RNA (Ribonucleic Acid) or ribonucleic acid is a polymer molecule that is involved in various biological roles in decoding, coding, regulation, and gene expression.

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DNA structure

DNA is the genetic material found in all living cells and most viruses. DNA carries the information necessary for protein synthesis and replication.

Structure of DNA double helix chain. Each chain is a polynucleotide, and consists of nucleotides, each of which is composed of three units of sugar, base and phosphate. Inside the nucleotide is a nucleoside, which is a sugar paired with a base. Each nucleotide in a polynucleotide is linked by the same chemical bonds (base bonds). The nucleotide structure consists of.

• One sugar molecule

There are two kinds of sugar, namely ribose (pentose) and dioxyribose (aldopentose).

• base pairs

There are two types of base pairs, namely purines and pyrimidines. Purines consist of adenine (A) and guanine (G) with hydrogen single bonds. Meanwhile, pyrimidine consists of cytosinine (S) and thymine (T). Base pairs are connected by hydrogen bonds, purines are paired with pyrimidine (A-T with two hydrogen bonds) whereas (G-S with three hydrogen bonds).

• Phosphate

Phosphates linked to pentose sugars form a bond called a phosphodiester bond.

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Characteristics of DNA

DNA has a chain-like structure, with a twisted double helix that can self-replicate. In addition, there are other characteristics of DNA, including:

• The size of haploid cells reaches 3x 10 9 base pairs
• One chromosome is ± 7 cm long
• The chain can be separated (denaturation due to alkali and hot temperatures)

Denaturation can occur when DNA is in hot conditions close to 1000 Celsius so it will separate, especially DNA with a partner A-T bases which only have two hydrogen bonds, because the G-C base pairs have 3 hydrogen pairs will be more resistant to hot. And can experience Renaturation when it returns to its all condition (temperature drops), with intact RNA meeting again with its suitable partner.

• Serves as genetic material (character carrier)

DNA as genetic material, functions in gene expression, DNA regulates all cell activities, and is able to form protein templates needed by cells.

• Replicates / multiplies itself into two with the same composition functions in protein synthesis.

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DNA replication

It should be noted that DNA replication is semi-conservative, that is, both DNA strands act as adepts for the manufacture of new DNA strands. Then it is also the process of preparing genetic material for division (reproduction). Prokaryotic cells are constantly replicating DNA. In eukaryotes, the timing of DNA replication is highly regulated, namely during the cell cycle phase, before mitosis or meiosis.

The replication speed of eukaryotic organisms is 10 times longer than that of prokaryotes (because the ribosomes in eukaryotic cells are outside the nucleus, so the mRNA must pass through the nuclear membrane). Meanwhile, replication of the human genome takes 8 hours. Replication is semi-conservative and occurs in two directions, the synthesis direction from 5 to 3. The following are the stages of DNA replication:

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Stages of DNA Replication

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  Initiation Stages

Opening of the Double Helix Chain with the help of DNA Helicase. Helicase converts ATP to ADP as energy to open and extend separate DNA chain branches. DNA helicase, is a protein that helps the DNA replication stage, consisting of:

• • Helicase II/III, which attaches the template whose trailing chain ('3-5') becomes directional ('5-3')
  • Rep protein, which binds to the first chain being synthesized and is rerouted to '3-5'

• DNA begins to be replicated by DNA Polymerase III

Assisted by topoisomerase (DNA gyrase) which reduces the tension of the DNA strands, after which the DNA strands Single strands are attached by single-stranded binding proteins to prevent the double helix from forming return.

• The DNA chain is extended to form a new single DNA strand.
  • Leading strand: new strands in the correct direction from '5-3'
  • Lagging strand: new strands that are directed from '3-5' so that they experience cracks in the strands
• Primary RNA has primase enzymes to attach primary RNA, primase enzymes are able to form Okazaki fragments. RNA primers start synthesizing DNA only once at the leading strand, whereas the lagging strand starts at each Okazaki fragment.
• The primase enzyme can combine with other polypeptides and at that time the primosome is active, the primosome changing the direction of synthesis from '3-5' to '5-3', the primosome will only appear when the primary RNA free.
• The RNA primers are released later, then taken over by DNA polymerase I to be synthesized until it approaches the parts of the Okazaki fragment that preceded it, then the direction of synthesis is changed to '5-3'
  Adjacent Okazaki fragments are joined by DNA ligase

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DNA Replication Hypothesis

There are three hypotheses about DNA replication that explain how the strands of the double helix of DNA make copies in the process of DNA replication, which are as follows:

• The first Conservative hypothesis, the strands of the DNA double helix form new strands in one piece
• Then Semi-conservative hypothesis, the strands of the DNA double helix open and then each form a new strand as a complement
• So Dispersal hypothesis, a mixture of the old and newly formed DNA double helix strands

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DNA Repair

DNA Repair is the process of repairing damaged DNA, including due to:

• Base modification (chemical changes, loss of bases, covalent bonds between adjacent bases)
• Failure of DNA transcription and translation
• Severe DNA damage (DNA breaks)

DNA repair is grouped in 3 ways, namely:

• Damage Revesal, immediately replaced

This is the easiest way because there is no need to cut the DNA, it just needs to be replaced.

• Damage Removal, removed

More complicated because it has to do the cutting to replace, and is divided into:

• • Base excision repair by simply replacing one damaged base and another.
  • Mismatch repair by replacing the mismatched base with enzymes.
  • Nucleotide excision repair by cutting one of the damaged DNA segments.

Damage Tolerance, tolerating fault, is divided into,

• • Homolongous recombination (HR), using sister chromatids to repair damage (without deletions).
  • Non homologous end joining (NHEJ), if the break is not the same then it will be flattened first with the exonucleuse, then there is a certain enzyme that works and will combine (with deletion).

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RNA structure

RNA is a macromolecule, which functions as a storage and distribution of genetic information that is only found in certain viruses.

RNA is a single polynucleotide chain or also called a single helix. Each ribonucleotide consists of three molecular groups, namely 5 carbons, a nitrogenous base and a phosphate group. In contrast to DNA, pyrimidine base pairs in RNA consist of cytosine (S) and uracil (U). Purine base pairs consist of adenine (A) and thymine (T).

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RNA type

There are three types of RNA that will be formed when needed in the process of protein synthesis, including:

• • ribosomal RNA (rRNA). RNAr is imprinted by DNA in the nucleus. RNAr is the main structural component in the ribosome which is arranged into subunits, which helps the attachment between the codon and the anticodon in the ribosome.
  • transfer RNA (tRNA). The tRNA has three short base sequences at one end called the anticodon, which carry the acid specific amino acids from the cytoplasm that are useful in protein synthesis, namely the sequencing of amino acids according to their codon sequence rRNAd.
  • Messenger RNA (mRNA), also known as messenger RNA (dRNA). RNAd is the genetic code (codon) from the core chromosome to the ribosome. The RNAd genetic code then becomes a template for determining the sequence of amino acids in the polypeptide chain.

• Protein Synthesis

Protein is the largest organic component in our body cells (10-15%). Cell proteins are markers for certain metabolic diseases. Therefore protein plays an important role in cell metabolism. Enzymes, vitamins, regulatory substances, certain hormones are also proteins.

• Protein Synthesis in Prokaryotes – Eukaryotic

Protein synthesis is a dynamic process, which can change depending on the environment. There are differences in the process of protein synthesis in prokaryotic and eukaryotic cells DNA in the cytoplasm, namely:

• • Prokaryotes:
    • DNA in the cytoplasm
    • The processes of transcription and translation occur in the cytoplasm
    • The primary RNA product resulting from the transcription of DNA can function immediately
  • Eukaryotic.
    • DNA in the nucleus
    • The process of transcription occurs in the nucleus while translation occurs in the ribosome
    • Primary RNA must undergo a maturation process beforehand to become functional RNA.

In eukaryotic cells, the process of transcription and maturation of this primary RNA occurs in the cell nucleus. Maturation is in the form of a capping process for making caps at the 5' end with 7-methyl-guanosine. Besides Capping; There is also the addition of a polyadenylate tail at the 3' end. The amount of addition of poly A varies from 100-200 nitrogen bases.

Furthermore, the primary RNA undergoes splicing (cutting/depletion of introns by SnRNA and HnRN Protein with ribosomes, which are ribonucleic enzymes as a catalyst). When RNA splicing occurs, hook-like structures are formed. After completing this process, the primary RNA has become functional (becomes m-RNA maturation). The next phase is the transport of this mature RNA through the nuclear membrane to the ribosomes in the cytoplasm.

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Protein Synthesis Stages

Protein synthesis occurs in two stages, namely transcription and translation.

• Transcription

At this stage the codons on the DNA strands are copied into RNA. m-RNA serves as a messenger between DNA and proteins that will be synthesized later. This process takes place in a transcription system called a cistron. Direction of copying of codons from 5' to 3' ends

From place of initiation (AUG) to place of termination (UAG, UAA, UGA)
RNA polymerase attaches to the promoter of the DNA strand and separates the two DNA strands.
The nucleotide chains of RNA are free to move and the hydrogen bonds complete the bases of the DNA chains.
RNA polymerase links to the RNA nucleotide chain in the 5' to 3' direction.
The RNA chain that has been formed breaks away from the DNA chain.
mRNA is transported to the endoplasmic reticulum.
Then the ribosome reads the mRNA sequence. To convert mRNA into protein form, tRNA is used to read mRNA sequences. One read translates 3 nucleotides into one amino acid.

The requirement for transcription to occur is the interaction between the promoter and the RNA polymerase enzyme. Promoter is a trigger of transcription and an absolute requirement for transcription to occur. Enzyme RNA Polymerase:

In prokaryotes there is only 1 kind of RNA-Polymerase
In eukaryotes there are 3 kinds of RNA-Polymerase (I, II, III)

The first polymerase I coding for ribosomal DNA
Second Polymerase II encode the genes that work during transcription, pre m-RNA, snu-RNA, m-RNA and a small part of sn-RNA
Final polymerase III encode t-RNA and small RNAs for example sn-RNA

There are three stages, namely:

Initiation: the emergence of a promoter as a result of the attachment of RNA polymerase to a particular section of DNA.
Elongation: occurs during the transcription process, until the promoter is at the end (terminator).
Termination: the promoter stops transcribing the DNA due to the terminator, and produces the m-RNA strand

In one DNA strand, there are many RNA polymerases that are able to work along certain sections, which can produce m-RNA, so cells are able to produce many proteins of the same type in a short time also.

• translation

Translation is the process of translating m-RNA codons into polypeptides (amino acid sequences) in the ribosome. Translation of one codon produces one amino acid. It starts with the translation of the triplet codons from start to finish.

The translation stage includes r-RNA (ribosome RNA). Ribosomes are divided into two types, namely small sub units which is composed of one m-RNA, while the large sub unit is composed of two m-RNA and several types of protein in inside. These two subunits will not unite as long as protein synthesis has not occurred.

This process is divided into three stages, namely: initiation, elongation, and termination.

• • Initiation

It begins with the attachment of the small ribosome unit to the 5' end of RNAd.
The first tRNA (initiator) arrives carrying the amino acid methionine with the UAC anticodon on RNAd right at the AUG start codon at the P position.
The process of attaching a large unit ribosome to a small unit ribosome.
The large unit ribosome has 3 special tRNA attachment positions, namely A, P, and E. The rightmost position of A is the entry point for tRNA which carries amino acids. Then the P position in the middle as a place for tRNA to release amino acids. Meanwhile, the E position on the far left is where the tRNA exits from the ribosome.

• • elongation

Elongation begins with the emergence of a new t-RNA that carries a new amino acid and anti-codon.
A shift occurred in the t-RNA with the opening amino acid (AUG-lock) with the new t-RNA with anti codon and new amino acid (large sub unit has three sides or places, namely E-site, P-site and A-site.

So the shift from the A-site to the P-site, but at the beginning of opening the key t-RNA immediately occupies the A-site and shifts until it is released at the E-site)
New t-RNA arrives and then there is elongation of the amino acid sequence which is then arranged into a polypeptide

• • Termination
    • The polymerase detaches at the terminator (termination codon)
    • The releasing factor protein binds to a stop codon.
    • Addition of water to the polypeptide chain.
    • Translation stops because the stop codon cannot bind to an aminosylRNA.
    • The polypeptide chain detaches from the ribosome.
    • The process ends when the ribosome releases the mRNA and dissociates into the 3' and 5' subunits

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Discussion on DNA

DNA has a nucleic acid consisting of polynucleotides of diocnucleotide units whose building blocks are dioxynucleotides. This genetic information is generally a collection of commands that regulate cells to do something.

DNA in English is called deoxyribonucleic acid, while in Indonesian it is called Deoxyribonucleic Acid. The chemical composition of DNA is a polymer made up of long chains of nucleotides.

• DNA function

The main function of DNA is to carry genetic material. However, the function of DNA is very broad, namely as follows:

• • Carrying genetic material from generation to generation
  • Control life directly or indirectly
  • As an auto catalyst or self-replicating
  • As a heterocatalyst or perform synthesis of other compounds

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Discussion on RNA

RNA has a nucleic acid consisting of polynucleotides of mononucleotide units. RNA polymers are composed of alternating bonds between the phosphate group of one nucleotide and the ribose sugar group and another nucleotide.

• RNA function

For the function of RNA as follows.

• • As a store of information.
  • As an intermediary between DNA and protein in the process of genetic expression as it applies to living organisms.

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Difference between DNA and RNA

• The pentose portion of DNA is ribose, while the pentose portion of RNA is dioxyribose.
• The molecular shape of DNA is a double helix while the shape of the RNA molecule is in the form of a single chain that is folded, so it is similar to a double chain.
• RNA contains the bases adenine, guanine and cytosine like DNA but RNA does not contain thymine which instead contains uracil.
• DNA is in the chromosomes while RNA depends on the type of RNA like the second RNA found in p RNA or t RNA nuclei are found in the cytoplasm while r RNA (ribosome RNA) is found in the cytoplasm ribosome.
• Naturally DNA forms RNA while RNA forms proteins which are essential for living things such as forming blood muscles, body organs, hormones, enzymes and others.

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