If the amino acid sequence of the two organisms are similar , would their DNA be also similar ? why ?

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Yes. If the amino acid sequence of two organisms are similar, then the organisms’ DNA sequences would also be similar. The central dogma of biology states that DNA contains the key for RNA, which then codes for proteins.

Transcription and translation are the two phases of protein synthesis.

During transcription, the two strands of DNA unwind. One of the strands serves as a template to make an mRNA strand. Each set of three nucleotides on an mRNA is called a codon. These codons will be important in the second phase of protein synthesis called translation.

After the mRNA is created during transcription, it migrates to the cytoplasm via a nuclear pore.  

During translation, mRNA, ribosomes, rRNA, tRNA, and amino acids work together to make the protein strand.

Once in the cytoplasm, the mRNA and ribosomes attach. The ribosomes serve as scaffolds that match the codons on mRNAs to the anticodons on the tRNAs. Anticodons are sets of three nucleotides on the base of a tRNA that are complementary to mRNA codons.

As the ribosome moves down the mRNA during translation, additional tRNA anticodons are matched with the complementary mRNA codons. On the top of tRNA are amino acids. In this way, amino acids that form a protein are arranged in the correct order.  When two amino acids are adjacent to one another, a peptide bond forms. The polypeptide chain continues to grow until a stop codon is reached.

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