CentralCentral dogma of dogma of lifelife

What is central dogma of life?What is central dogma of life?

The set of ideas that describes how the The set of ideas that describes how the cell uses the information stored in DNA is cell uses the information stored in DNA is called the central dogma.called the central dogma.

The central dogma of biology is the The central dogma of biology is the information in biological systems only information in biological systems only flows one way from DNA to RNA to flows one way from DNA to RNA to protein.protein.

Who gave the central dogma theory Who gave the central dogma theory ??

The central dogma of biology was a The central dogma of biology was a concept devloped by Francis Crik in 1958 .concept devloped by Francis Crik in 1958 .

He say that information can’t be transfered He say that information can’t be transfered back to protein from protein or nucleic back to protein from protein or nucleic acid. acid.

Steps of central dogma .Steps of central dogma .

1)1) Transcription .Transcription .

2)2) Translation .Translation .

TranscriptionTranscription

First step of central dogma is called First step of central dogma is called transcription .transcription .

Transcription is the process of using DNA as a Transcription is the process of using DNA as a template to synthesize RNA .template to synthesize RNA .

A temporary copy is made of the necessary A temporary copy is made of the necessary information in a DNA molecule so that protein information in a DNA molecule so that protein synthesis can occur . This operation is called synthesis can occur . This operation is called transcription Which means to transfer data form transcription Which means to transfer data form one form to another . one form to another .

In these case DNA language is copied to RNA In these case DNA language is copied to RNA language.language.

Using this process the genetic information Using this process the genetic information stored as a DNA chemical code is carried stored as a DNA chemical code is carried in the form of an RNA molecule .in the form of an RNA molecule .

Later these RNA molecule will be used as Later these RNA molecule will be used as template for creating a protein .template for creating a protein .

Many types of RNA can be synthesized, Many types of RNA can be synthesized, the three most important are messenger the three most important are messenger RNA (mRNA), transfer RNA (tRNA), and RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA) .ribosomal RNA (rRNA) .

mRNA carries the blueprint for makingthe mRNA carries the blueprint for makingthe necessary enzymes.necessary enzymes.

tRNA and rRNA are used in process of tRNA and rRNA are used in process of assembling the amino acids .assembling the amino acids .

Translation Translation

Translation is the process of using the Translation is the process of using the information of RNA to direct the ordered information of RNA to direct the ordered assembly of amino acids.assembly of amino acids.

The word translation refers to the fact that The word translation refers to the fact that nucleic acid language being changed to nucleic acid language being changed to the protein language ,the protein language ,

For process of translation translation For process of translation translation dictionary is required .dictionary is required .

Translation dictionaryTranslation dictionary

In these dictionary each 3 nucleotide In these dictionary each 3 nucleotide combination is called codon.combination is called codon.

The process of translation can be brake The process of translation can be brake down in three steps.down in three steps.

1.1. Initiation Initiation

2.2. ElongationElongation

3.3. Termination .Termination .

InitiationInitiation

The initiation process involves first The initiation process involves first joining the mRNA, the initiator joining the mRNA, the initiator methionine-tRNA, and the small methionine-tRNA, and the small ribosomal subunit. Several “initiation ribosomal subunit. Several “initiation factors”--additional proteins--are also factors”--additional proteins--are also involved. The large ribosomal subunit involved. The large ribosomal subunit then joins the complex.then joins the complex.

ElongationElongation

TerminationTermination

Three codons are called “stop codons”. They Three codons are called “stop codons”. They code for no amino acid, and all protein-coding code for no amino acid, and all protein-coding regions end in a stop codon.regions end in a stop codon.

When the ribosome reaches a stop codon, there When the ribosome reaches a stop codon, there is no tRNA that binds to it. Instead, proteins is no tRNA that binds to it. Instead, proteins called “release factors” bind, and cause the called “release factors” bind, and cause the ribosome, the mRNA, and the new polypeptide ribosome, the mRNA, and the new polypeptide to separate. The new polypeptide is completed.to separate. The new polypeptide is completed.

Note that the mRNA continues on past the stop Note that the mRNA continues on past the stop codon. The remaining portion is not translated: codon. The remaining portion is not translated: it is the 3’ untranslated region (3’ UTR).it is the 3’ untranslated region (3’ UTR).

TerminationTermination

Overview of translationOverview of translation

Difference of central dogma in Difference of central dogma in prokaryotes and eukaryotes . prokaryotes and eukaryotes .

Major diffrence between prokaryotes and Major diffrence between prokaryotes and eukaryotes is that splicing occur in only eukaryotes is that splicing occur in only prokaryotes during process of central prokaryotes during process of central dogmadogma

ReplicationReplication

DNA replication is the process of producing two DNA replication is the process of producing two identical copies from one original DNA identical copies from one original DNA molecule .molecule .

This biological process occurs in all living This biological process occurs in all living organisms and is the basis for biological organisms and is the basis for biological inheritance .inheritance .

DNA is composed of two strands and each DNA is composed of two strands and each strands of original DNA molecule serves as strands of original DNA molecule serves as template for the0 production of complementary template for the0 production of complementary strand, a process referred to as strand, a process referred to as semiconservative replication .semiconservative replication .

DNA ReplicationDNA Replication

The The DNADNA duplication. duplication.

The transfer the genetic information from a The transfer the genetic information from a parent to a daughter cell. parent to a daughter cell.

The The DNADNA base sequences are precisely copied.base sequences are precisely copied.

DNA ReplicationDNA Replication 2 DNA Polymerase enzymes are required to replicate 2 DNA Polymerase enzymes are required to replicate

a single molecule of DNAa single molecule of DNA Each DNA Polymerase Each DNA Polymerase

unwinds the helical DNA moleculeunwinds the helical DNA molecule breaks the H-bonds between the complimentary breaks the H-bonds between the complimentary

strands of DNA creating a strands of DNA creating a replication forkreplication fork ““reads” the sequence of nucleotides along one of reads” the sequence of nucleotides along one of

the the ““originaloriginal” ” strands of DNA strands of DNA synthesizes a synthesizes a ““newnew” ” complementarycomplementary strand of DNA strand of DNA

for each of the for each of the ““originaloriginal” ” strands from free strands from free nucleotides in the nucleusnucleotides in the nucleus

After replication is completed, the cell contains 46 After replication is completed, the cell contains 46 pairs of DNA moleculespairs of DNA molecules 92 total92 total

Semiconservative DNA ReplicationSemiconservative DNA Replication The replication of DNA in this manner is considered to The replication of DNA in this manner is considered to

be be semisemiconservativeconservative because the because the resulting 2 resulting 2 molecules of double stranded DNA contain one molecules of double stranded DNA contain one ““originaloriginal” strand and one “” strand and one “newnew” strand” strand

DNA Replication: Enzymes DNA Replication: Enzymes involvedinvolved

Initiator proteins (DNApol clamp loader)Initiator proteins (DNApol clamp loader) HelicasesHelicases SSBPs (single-stranded binding proteins)SSBPs (single-stranded binding proteins) Topoisomerase I & IITopoisomerase I & II DNApol I – repairDNApol I – repair DNApol II – cleans up Okazaki fragmentsDNApol II – cleans up Okazaki fragments DNApol III – main polymeraseDNApol III – main polymerase DNA primase DNA primase DNA ligaseDNA ligase

Reverse transcriptionReverse transcription

It’s the process by whichthe genetic It’s the process by whichthe genetic information from RNA will be assembled information from RNA will be assembled into new DNA .into new DNA .

Reverse transcription is the transfer of Reverse transcription is the transfer of information from RNA to DNA .information from RNA to DNA .

This is known to occur in the case of This is known to occur in the case of reteroviruses such as a HIV and it’s also reteroviruses such as a HIV and it’s also occur in the case of telomere synthesis.occur in the case of telomere synthesis.

ReferncesRefernces

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