Question

 

In this discussion, you will explore how DNA information is turned into specific proteins. What is transcription and translation? What are the different types of mutations? In our next discussion, we will look at how these mutations, when occurring in specific genes, can lead to cancer.

Instructions

1. For your initial post, compete all of the following:

   Part 1

   1. Describe the basics of transcription and translation. Where in human cells does each of these processes occur?
   2. What are start and stop codons?
   3. What are insertion, deletion, and substitution mutations?
   4. What are frameshift, missense, nonsense, and silent mutations?
   5. Which type of mutation is most likely to cause a change in a protein’s structure and function (frameshift, missense, nonsense, and or silent mutations)? What is least likely to change the protein’s structure and function? Explain.

   Part 2

   1. Write your own sequence of DNA that could be turned into a protein. This should be approximately 30 letters long (10 codons). It should be in the format 3’ AAG CCC ….. 5’
   2. Be sure to include a start codon of “TAC” and a stop codon of your choice. Do not do any transcribing or translating at this time. Just include the DNA sequence in the 3’ to 5’ direction.
   3. Write a mutated sequence based on your first sequence above with either an insertion, deletion, or substitution mutations. Do not write anywhere what type of mutation has occurred. Just write the sequence itself.

Answer 1

PART 1

A.The production of RNA copies of DNA templates is known as transcription.It is catalysed by RNA polymerase or transcriptase.Three steps in transcription are :Iniation,elongation and termination.Transcription begins with the attachment of RNA polymerase enzyme with the promoter region of transcription unit and comes to an end when core enzyme reaches the terminator sites and diisociate from the DNA.

Translation is the process of converting mRNA(messenger RNA) to aminoacids encoded in them.Ribosomes begin to read the mRNA sequence from the 5' to 3' end.To convert themRNA inti protein,tRNA is used to read the mRNA sequence ,3 nucleotides at a time.

In eukaryotic cell,transcription occurs in nucleus and translation in cytoplasm.In prokaryotes both transcription and translation are coupled.

b.Start codon represents the 3 nucleotide sequence of the mRNA at which translation begins.The commmon start codon is AUG that also codes for methionine in eukaryotes.Stop codon represents the 3 nucleotide sequence in the mRNA where thetranslation stops.Stop codon includes UGA,UAA and UAG are the stop codons.

c.Insertion mutation is the mutation that occurs due to the addition of one or more nucleotide base pairs into the DNA sequence..This ncreasess the number of DNA basees in a gene.Deletion mutation is he mutation that ocurs due to the removel or deletion of nucleotide base pairs from the DNA sequence.Deletions occur when some errors occurs such that some nucleoyide may not be copied durind DNA replication.Substitution mutation is the mutation thet occurs when one of the base pair is removed and replaced with another base pair.This can change a codon and produce a different amino acid and bring slight changes in the protein.

d.Frameshift mutation is a genetic mutation.The entire frame for reading the codon is shifted.The insertion or deletion of bases can change the reading frame,resulting in a different translation than the original.

In missense mutation,a single nucleotide base changes due to misincorporation of nucleotide during DNA replication or during transcription or due to any mutagens.Due to this a different aminoacid gets substituted in the resulting protein.This can produce defective proteins.

The nonsense mutation converts a codon that encodes an aminoacid into a discontinue codon or stop codon .single mutation in the base in the DNA results in the termination of the translation of the mRNA.

Silent mutation occur when there is a misincorporation of nucleotide in DNA results in no change in the aminoacid sequence during protein synthesis.

e.Missense mutation is most likely to cause change in the protein's structure and function.Because missense mutation results in the substitution of an aminoacid by an entirely different amino acid in the protein.This substituted amino acid can make the protein defective or malformed.

Silent mutation is least likely to change the protein's styructure anmd function.Because eventhough there is a change in the bases,there is no change in the amino acid sequence.

part 2

A. 3' AAG CCC CCA AAA CAC AAG GGC GAA GCA TCA 5'

B. 3' ATC CCC CCA AAA CAC AAG GCG GAA GCA TAC 5'

C.3' AAG CCC CAA AAA ACA CAA GGG CGA AGC ATC A 5'