Question

Review Questions BIOL 260: Chapters 8-10, 13, 19 1. Consider a mutation involving the deletion of either 1, 2, or 3 nucleotides in the DNA of a bacterium. Which of these mutations (ie., deletion of 1, 2, or 3 nucleotides) would likely have the LEAST impact on the organism? Why? Include in your answer a comparison with the other two options to justify your reasoning. Think carefully about the impact each mutation would have on the ultimate protein coded for by the gene. 2. Spontaneous mutations of a single nucleotide, or point mutations, result from the incorporation of an incorrect nucleotide during DNA replication. Although these point mutations represent a change of the genotype of the organism, in some cases they may not change the phenotype, Please explain how this is possible. 3. Explain the process of gene expression. Include the components involved up through the final product 4. Consider all the E. coli bacteria of a particular strain and assume they all arose from a common ancestor and possess the exact same DNA in their chromosome. (Note that this is unlikely to really be true!) Explain why they could all have exactly the same DNA, but their RNA would likely vary widely from one cell in one location to another cell in another location Protein Synthesis & Mutations 5 6. Using the following coding DNA strand, give the mRNA sequence that would be transcribed and the primary structure of the polypeptide that would be synthesized (see the genetic code on the next page) DNA: 3' A GATTA CTCGA GCC GGG TAATC GG 5' mRNA: polypeptide: 6... Sickle-cell anemia is a genetic disorder, in which the sixth amino acid residue of the beta chain differs from normal, adult hemoglogin. Normal hemoglobin contains glutamic acid (Glu), where sickle-cell hemoglobin contains valine (Val). a. b. c. What are the codons for glutamic acid? What are the codons for valine? What base substitution mutation most likely occurred in the DNA in order to produce the allele for sickle-cell hemoglobin? Explain your answer.

Answer 1

The first part is not clear.

5)

the central dogma of the life defines that the protein is derived from the DNA information through a series of step.

transcription is the process by which DNA is read and corresponding mrnA/messenger RNA is produced. The mRNA should be in the 5'-3' diection inorder to poduce the potein so the template stand should hhave the polarity of 3'-5' so the anti sense stand is used in this case. its also worth noting that there is no thymine(T) in the RNA instead uracil(U) is pesent.

after the gene/DNA is transcripted to corresponding RNA, it is then converted to protein by the incorporation of the amino acids by tRNA by the process called translation.The triplet codon/ a group of 3 dna bases decide the amino acid.

AUG is the starting codon in universally and it is coded forr methionine. then elongation is carried out by tRNA and ribosomes and termination is done by the stop codons.

coming back to the question

the given sequence is in 3'-5' orientation which is the right strand to transcript.

template- 3' AGA TTA CTC GAG CCG GGT AAT CGG 5'

mRNA- 5' UCU AAU GAG CUC GGC CCA UUA GCC 5'

protein sequence- SER ASN GLU LEU GLY PRO LEU ALA.

6)

Second Letter Phe Tyr UGU Ser UUU UUC UUA UUG UCU UCC UCA UCG UAU UAC UAA UAG Leu Stop Stop UGC UGA UGG His CUU CUC CUA CUG CCU Leu CCC CCA CCG Pro CAU CAC CAA CAG CGU CGC CGA CGG 1st 3rd hoc | 0 Poc | 0 Poc|e Poc letter Asr letter A AUU AUC AUA AUG ACU lle ACC ACA Met ACG Thr AAU AAC AAA AAG AGU AGC AGA AGG GAU GAC Asp GUU GUC GUA GUG GCU GCC GCA GCG Val Ala GAA GAG GGU GGC GGA GGG Glu

Sickle cell anemia is a genetic disorrder where the oval shaped circular blood RBC is deformed to crescent/ sickle shape. The after effect of this defomation will make oxygen transport less efficient.

Codons of glutamic acid - GAA, GAG

Codons for valine- GUU, GUC, GUA, GUG

a single point mutation /a missense mutation in the beta-hemoglobin gene converts GAG codon into GUG, which encodes the amino acid valine instead of glutamic acid respecticvely.