Anonymous asked in Science & MathematicsBiology · 1 decade ago

A portion of a specific DNA molecule consists of the following seq. of nucleotide triplets:TAC GAA CTT CGC?

This DNA sequence codes for the following short polypeptides: Methionine-leucine-glutamic acid-proline-arginine Describe the steps in the synthesis of this polypeptide. What would be the effect of a deleltion or an addition in one of the DNA nucleotides? What would be the effect of a substitution in one of the nucleotides?

2 Answers

  • 1 decade ago
    Best Answer

    Central dogma could also be known as protein synthesis. It involves three stages they are known as replication of DNA, transcription of the DNA to the mRNA and finally, the translation of mRNA into proteins.

    In replication, the DNA will copies itself. The process will start with helicase unwinding the double stranded DNA. Copying will be done from a 5 prime to 3 prime. During the process of copying, there will be a leading strand and a lagging strand. The leading strand will be copying in a continuous movement whereas the lagging strand will only copy segment be segment. The DNA liagase will then join the segments.

    Transcription is the process of rewriting. This is necessary as the DNA is unable to leave the nucleus to carry the information to the cytoplasm. The mRNA will be the messanger to bring the information to the cytoplasm. The mRNA will only start rewriting the codes after detecting the start codon. This process will stop when the stop codon is dectected. AFter the process is stopped, it will detach itself and undergo a process known as splicing. During splicing, the unwanted or nonsence segment of DNA also known as the introns will be removed. Splicing is important to prevent unwanted message from producing abnormal proteins. After splicing, the mRNA will move to the cytoplasm.

    Finally, translation will take place. The two important components are the mRNA template and the ribosome. Amino acid will production when the ribosome recognises the start codon from the mRNA template. After the first amino acid is produced, the tRNA will come to match it while the ribosome moves on to the second set of codon and second set of the amino acid will be matched with the second tRNA. The third tRNA will be matched to the third amino acid by the same process. When three amino acid is matched my the tRNA, amino acid 1 will bond with amino acid 2 and amino acid 2 will bond with amino acid 3. This chain is called the polypeptite chain or also known as protein. This process will carry on until the ribosome dectects the stop codon..

    If anyone of the DNA nucleotides is added or deleted or replaced, abnormal proteins may be produced. Some of the triple coden produces the same type of coden, thus, some of these changes of the nucleotides may produce the same type of proteins. However, during the splicing stage, the abnormal nucleotides may be spotted and removed.

  • 1 decade ago

    If there is a deletion or an addition, then there will be what is referred to as a "Frameshift" mutation. This is where the codons are all one nucleotide off of the correct sequence. This could have drastic effects on what amino acids are produced.

    Substitution of one of the nucleotides would only have an effect on the codon where it occured. Therefore, only one amino could possibly be incorrect. If the substitution occurs in the 3rd nucleotide of the codon, then there is usually not a problem as the same amino acid is still produced.

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