Concept explainers
As shown in Figure 14.12, four regions within the trpL mRNA can form stem-loops. Let’s suppose that mutations have been previously identified that prevent the ability of a particular region to form a stem-loop with a complementary region. For example, a region 1 mutant cannot form a 1-2 stem-loop, but it can still form a 2-3 or 3-4 stem-loop. Likewise, a region 4 mutant can form a 1-2 or 2-3 stem-loop but not a 3-4 stem-loop. Under each of the following sets of conditions, would attenuation occur?
A. Region 1 is mutant, tryptophan is high, and translation is not occurring.
B. Region 2 is mutant, tryptophan is low, and translation is occurring.
C. Region 3 is mutant, tryptophan is high, and translation is not occurring.
D. Region 4 is mutant, tryptophan is low, and translation is not occurring.
Want to see the full answer?
Check out a sample textbook solutionChapter 14 Solutions
Genetics: Analysis and Principles
- The following figure represents the primary transcript of a typical eukaryotic protein-coding gene: Polyadenylation site Exon 1 Intron 1 Exon 2 Intron 2 Еxon 3 bp: 1 50 600 945 1205 1393 1725 a. What is the size in bases of the fully processed, mature mRNA? Assume a poly (A) tail of 200 adenine residues in your calculations. b. This primary transcript is responsible for the production of a 294 amino acid protein in the liver and a 270 amino acid protein in the brain. Explain how this is possible. 2.arrow_forwardConsider the now dominant variant of the SARS-CoV-2 called the D614G mutation: a) The mutation changes an Aspartate (D, Asp) to a Glycine (G, Gly) at nucleotide position 614 (that’s why it’s called the D614G mutant) in the S1 subunit of the Spike protein. Using only the information above and a codon table, what are the mRNA codon sequences of the 2019-dominant and 2020-dominant Spike proteins? Note the figure above is not needed toanswer the question. Report in 5’ to 3' orientation __________________________________________ b) What type of substitution is this? In your answer, address the following: • The expected substitution in base sequence (e.g., A à C)• If the mutation is synonymous, nonsynonymous, or a frameshift• If the mutation is a transition or a transversion c) The mutation increases infectivity by reducing the stability of the Spike protein such that it can remain in the open conformation more often. The open conformation increases the chances of binding to the host ACE2…arrow_forwardA group of researchers are trying to find out whether a specific intron follows the splicing mechanism for Group I or Group II introns. They start out with two samples, each containing sufficient buffer conditions for self-splicing to occur, and a strand of mRNA that is 4,500 nt long that includes the intron of interest, which is 500 nt long (see schematic below). Sample 1 has nothing else added, whereas sample 2 has additional free guanosines. Intron 1,000 nt 500 nt 3,000 nt After incubating the samples for a sufficient amount of time for the reaction to occur, the researchers visualize the products from both samples on a DNA agarose gel, and then conclude that the intron is a Group II intron. a) Please predict the results from the DNA gel for both samples 1 and 2 by drawing the bands in the blank gel with DNA ladder provided below: How many bands are seen for each sample? What are the lengths of the bands? Sample 1 b) 5,000 nt 4,000 nt 3,000 nt 1,000 nt 500 nt 250 nt Sample 2 Draw…arrow_forward
- Knowing that the genetic code is almost universal, a scientist uses molecular biological methods to insert the human β-globin gene (Shown in Figure 17.11) into bacterial cells, hoping the cells will express it and synthesize functional β-globin protein. Instead, the protein produced is nonfunctional and is found to contain many fewer amino acids than does β-globin made by a eukaryotic cell. Explain why.arrow_forwardTay Sachs disease is an autosomal recessive disease in which a protein – Hex A - is abnormal. To make the Hex A protein: The promoter and transcription termination sites are 33,000 base pairs apart. The Hex A protein has 600 amino acids 5’ and 3’ UTR’s are each 500 bp long. a)How many base pairs would you expect in the final mRNA? Show your work b)How many bases were spliced out? Show your workarrow_forwardThe primary protein structure is shown in Figure 9-3(a).Where in the mRNA (near the 5′or 3′end) would a mutation in R2 be encoded?arrow_forward
- a) Two of the following three mRNA sequences code for the same protein. Delete the sequence which does NOT code for the same protein as the other two. [ /1] #1 UUU CCU AGU GGU #2 UUC CCA AGC GGC #3 UUC CCG AGA GGA b) Despite the fact that one of the mRNA sequences above codes for a different protein, it IS possible that it will be translated into the same protein as the other two. Based on what you have learned in this unit, explain how this might happen.arrow_forwardThe IMD2 promoter contains three upstream transcription start sites (TSS) that are utilized under high GTP conditions and a single downstream TSS (-106) that is normally only utilized under low GTP conditions. In a wild type cell, expression of IMD2 mRNA only occurs if transcription initiates from the -106 TSS. In 300 words or less, describe: 1.) The normal function of Ssl2, and 2.) why a mutation in Ssl2, that increases its catalytic rate, would allow expression of the IMD2 ORF under high GTP conditions. (Conditions under which the IMD2 ORF is NOT expressed in the wild type.)arrow_forwardConsider the following mRNA base sequence 5' CUG-CAC 3' (a) What dipeptide is coded for by this mRNA? (b) What dipeptide is formed if a mutation converts CUG to CUU? (c) What dipeptide is formed if a mutation converts CAC to CGC? (d) What dipeptide is formed if a mutation converts CUG to CUU and CAC to CGC?arrow_forward
- The following logo plot represents the preferred cis-regulatory sequences (i.e. transcription factor binding site) of bHLH transcription factor FOSL1. C 1 2 3 4 5 6 7 8 9 10 11 position Would you expect this sequence to be recognized by a monomer, a homodimer, or a heterodimer of the protein? Explain your answer. (short phrases are sufficient; please write your answer into the template below) A- В I A -l expect FOSL1 to bind as a: (monomer, homodimer, heterodimer; please choose) B - short explanation: information content (bit) !!arrow_forwardShown here is a theoretical viral mRNA sequence 5′-AUGCAUACCUAUGAGACCCUUGGA-3′ (a) Assuming that it could arise from overlapping genes, how many different polypeptide sequences can be produced? Using the chart in Figure 12–7, what are the sequences? (b) A base-substitution mutation that altered the sequence in part (a) eliminated the synthesis of all but one polypeptide. The altered sequence is shown below. Use Figure 12–7 to determine why it was altered. 5′-AUGCAUACCUAUGUGACCCUUGGA-3′arrow_forwardImagine you are going to label a gene associated with apoptosis in Symbiodiniaceae with a Yellow Fluorescent Protein (YFP). To generate the YFP, you know the pre-MRNA looks as follows: Unspliced YFP premature mRNA Сap 5' UTR Exon 1 Intron Exon 2 Intron Exon 3 3' UTR Poly-A tail If Exon 2 is also required for mRNA stability, what can be predicted from the possible spliced alternative isoforms formed? One of the isoforms will not have a poly-A tail O The alternative splicing of YFP pre-MRNA prevents 5'-capping The MRNA isoform without Exon 2 will be degraded faster than the other isoform Exon 2 will be added to isoform B later to correct the mistake in splicing The protein translated from one of the mRNA isoforms will possess an additional functional domainarrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education