Concept explainers
You are studying mutations in a bacterial gene that codes for an enzyme whose amino acid sequence is known. In the wild-type protein, proline is the fifth amino acid from the amino terminal end. In one of your mutants with nonfunctional enzyme, you find a serine at position number 5. You subject this mutant to further mutagenesis and recover three different strains. Strain A has a proline at position number 5 and acts just like a wild-type strain. Strain B has tryptophan at position number 5 and also acts like wild type. Strain C has no detectable enzyme function at any temperature, and you can’t recover any protein that resembles the enzyme. You mutagenize strain C and recover a strain (C-1) that has enzyme function. The second mutation in C-1 that is responsible for the recovery of enzyme function does not map at the enzyme locus.
a | What is the |
b | Why does strain B have a wild-type |
c | What is the nature of the mutation in strain C? |
d | What is the second mutation that arose in C-1? |
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Chapter 8 Solutions
ND STONY BROOK UNIVERSITY LOOSELEAF GENETICS: FROM GENES TO GENOMES
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- There are five substitution mutations in the dark-colored mutant Mc1r gene. Compare the DNA sequence of the light-colored wild-type Mc1r gene with the DNA sequence of the dark-colored mutant Mc1r gene. Indicate the locations of the five mutations by changing the font color to YELLOW for the five single DNA nucleotides that are mutated in the mutant Mc1r gene table. Using the information in the introduction, determine whether each of these mutations is a silent, missense, or nonsense mutation. Using the mutant Mc1r gene data, fill in the columns (including DNA, mRNA, and amino acid) in gene table 2 that contain a silent mutation with BLUE. Likewise, fill in the columns that contain a missense mutation with RED. Shade any columns that contain nonsense mutations with GREEN. Then Of the five mutations you identified in the mutant Mc1r gene, how many are: substitutions insertions deletions (Enter a number on each line.) 2. Of the five mutations…arrow_forwardAfter Drosophila DNA has been treated with a restriction enzyme, the fragments are inserted into plasmids and selected as clones in E. coli. With the use of this “shotgun” technique, every DNA sequence of Drosophila in a library can be recovered.a. How would you identify a clone that contains DNA encoding the protein actin, whose amino acid sequence is known?b. How would you identify a clone encoding a specific tRNA?arrow_forwardAs part of a project investigating potential new drug targets in the fight against malaria, you are seeking to clone the gene for a protein from the malaria parasite Plasmodium falciparum. You wish to express this protein in BL21 (DE3) cells, a standard laboratory strain of Escherichia coli. After purification of your protein, you run an SDS-PAGE gel and notice that the major band has lower molecular weight than expected, so you fear you are getting a truncated version. (a) Give TWO possible causes of your protein becoming truncated. explainarrow_forward
- As part of a project investigating potential new drug targets in the fight against malaria, you are seeking to clone the gene for a protein from the malaria parasite Plasmodium falciparum. You wish to express this protein in BL21 (DE3) cells, a standard laboratory strain of Escherichia coli. After purification of your protein, you run an SDS-PAGE gel and notice that the major band has lower molecular weight than expected, so you fear you are getting a truncated version. 1. What technique could you use to confirm that you are obtaining a shortened version of your intended protein? explainarrow_forwardYou are interested in studying resistance to heavy metals and have selected the yeast Saccharomyces cerevisea to conduct your studies. You have recovered a deletion mutant that does not tolerate high concentrations of zinc (grows poorly in zinc containing media ) and have designated the mutant pgz-1 (for poor growth in zinc ). (a) What is the advantage to the type of mutant used in this work? What class of mutagen was likely use to generate pgz-1? ( b) Do you expect the PGZ gene to be expressed in your mutant? Explain.arrow_forwardThe sequence at one end of one strand of the Drosophilatransposon Mariner is shown below (dots indicatesequences within the transposon):5′ TTAGTTTGGCAAATATCTCCCTTCCGCCTTTTTGATCTTATGT... 3′You obtain a mutant bacterial strain tagged with anengineered Mariner transposon, cut the genomicDNA from this strain with the restriction enzymeMboI (whose recognition site is ^GATC), and circularize the resultant DNA fragments by diluting therestriction enzyme digest and adding DNA ligase.a. Design two 17 bp PCR primers that you could useto identify (by inverse PCR) the gene into whichthe transposon inserted.b. What DNA sequence will be amplified from thecircularized fragments of the mutant genome?Show the extent of this DNA sequence on a mapof the genome of the mutant strain, indicating thelocations of the transposon insertion and any relevant sites for the enzyme MboI.arrow_forward
- The DNA sequence of one strand of a gene from threeindependently isolated mutants is given here (5′ endsare at left). Using this information, what is the sequence of the wild-type gene in this region?mutant 1 ACCGTAATCGACTGGTAAACTTTGCGCGmutant 2 ACCGTAGTCGACCGGTAAACTTTGCGCGmutant 3 ACCGTAGTCGACTGGTTAACTTTGCGCGarrow_forwardA molecular geneticist hopes to find a gene gene in human liver cells that codes for an important blood clotting protein. He knows that the nucleotides sequence of a small part of the gene is GTGGACTGACA. briefly explain how to obtain the desired genearrow_forwardSuppose a researcher previously cloned gene Y into M13 bacteriophage vector. Gene Y encodes a product called peptide Y. A region of gene Y contains the DNA sequence ATG-CGC-GAA-CTG-GTG-AAC-TAA. The researcher wishes to change a Val residue to an Ala residue in this region of peptide Y using site-directed mutagenesis. What should be the sequence of the mutant oligonucleotide primer in this region? You may use a codon table. mutant oligonucleotide primer sequence: GGC-GGC-GAA-CTG-GTG-AAC-TAA Incorrectarrow_forward
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