An interesting phenomenon found in vertebrate DNAis the existence of pseudogenes, nonfunctional copiesof a gene found elsewhere in the genome. Some pseudogenes appear to have originated as double-strandedDNA copies of mature mRNA inserted into the chromosome; these copies later underwent mutations tomake them into pseudogenes.a. What sequence information might provide cluesthat the original source of some of these pseudogenes is cDNA copied in cells from mRNA andthen inserted into the genome?b. Would this mechanism of generating pseudogenesbe more likely to have operated if the pseudogenewas part of a gene family clustered in one region ofthe genome, or if it was instead part of a genefamily whose members are scattered around thegenome? Explain

An interesting phenomenon found in vertebrate DNAis the existence of pseudogenes, nonfunctional copiesof a gene found elsewhere in the genome. Some pseudogenes appear to have originated as double-strandedDNA copies of mature mRNA inserted into the chromosome; these copies later underwent mutations tomake them into pseudogenes.a. What sequence information might provide cluesthat the original source of some of these pseudogenes is cDNA copied in cells from mRNA andthen inserted into the genome?b. Would this mechanism of generating pseudogenesbe more likely to have operated if the pseudogenewas part of a gene family clustered in one region ofthe genome, or if it was instead part of a genefamily whose members are scattered around thegenome? Explain

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter11: Genome Alterations: Mutation And Epigenetics

Section: Chapter Questions

Problem 10QP: If the coding region of a gene (the exons) contains 2,100 base pairs of DNA, would a missense...

See similar textbooks

Similar questions

Trinucleotide repeat expansions (TNREs) are associated with severaldifferent human inherited diseases. Certain types of TNREsproduce a long stretch of the amino acid glutamine within theencoded protein. When a TNRE exerts its detrimental effect byproducing a glutamine stretch, are the following statements true orfalse?A. The TNRE is within the coding sequence of the gene.B. The TNRE prevents RNA polymerase from transcribing thegene properly.C. The trinucleotide sequence is CAG.D. The trinucleotide sequence is CCG.
Suppose you are a research assistant ina lab studying DNA-binding proteins. You have been giventhe amino acid sequences of all the proteins encoded bythe genome of a certain species and have been asked to findcandidate proteins that could bind DNA. What type of aminoacids would you expect to see in the DNA-binding regions ofsuch proteins? Explain your thinking.
Some exons in the human genome are quite small (lessthan 75 bp long). Identification of such “microexons” isdifficult because these distances are too short to reliablyuse ORF identification or codon bias to determine ifsmall genomic sequences are truly part of an mRNAand a polypeptide. What techniques of “gene finding”can be used to try to assess if a given region of 75 bpconstitutes an exon?
Researchers have successfully used gene therapy toameliorate some human genetic diseases by adding anormal gene copy to cells whose genomes originallyhad only nonfunctional mutant copies of that gene.For example, a form of blindness due to the lack of asingle protein called RPE65 has been reversed byintroduction of a normal RPE65 gene to cells of theretina of adults.a. The success of this gene therapy approach providesus with clues about the role of the RPE65 proteinin the retina. Do you think that RPE65 is neededfor the proper development of the human eye?b. Can you see a potential difficulty in applying this genetherapy approach for diseases like microcephaly?
If the coding region of a gene (the exons) contains 2,100 base pairs of DNA, would a missense mutation cause a protein to be shorter, longer, or the same length as the normal 700 amino acid proteins? What would be the effect of a nonsense mutation? A sense mutation?
Most laboratory strains of E. coli contain site-specific DNA methylases. The methylase encodedby the dam gene (Dam methylase) transfers a methyl group from S-adenosylmethionine (SAM) tothe N6 position of the adenine residues in the sequence GATC. The Dcm methylase (encoded bythe dcm gene) methylates the internal cytosine residues in the sequences CCAGG and CCTGG atthe C5 position.The E. coli strain used in this experiment is mutated so Dcm and Dam methylases are notfunctional. What is the advantage of using dcm or dam mutants when the E. coli will be a host torecombinant DNA? HINT – If the E. coli methylates the DNA in these cells, then how would thisaffect the activity of restriction endonucleases
. You are studying proteins having roles in translation inthe mouse. By BLAST analysis of the predicted proteinsof the mouse genome, you identify a set of mouse genesthat encode proteins with sequences similar to those ofknown eukaryotic translation-initiation factors. You areinterested in determining the phenotypes associatedwith loss-of-function mutations of these genes.a. Would you use forward- or reverse-genetics approaches to identify these mutations?b. Briefly outline two different approaches that youmight use to look for loss-of-function phenotypes in oneof these genes.
a. Very few if any eukaryotic genes contain tractswith more than 25 As or Ts in a row, yet almost alleukaryotic mRNAs have a tract with more than100 As in a row. How is this possible?b. Scientists know the nucleotide sequences that directthe termination of bacterial gene transcription, butthey generally have little idea about the nature ofthe nucleotide sequences that direct transcriptiontermination in eukaryotic cells. Explain the basisof this statement.
A mutant DNA strand was transcribed then translated to proteins. a. What is the protein product of the mutant DNA strand? The sequence of the mutant strand is shown below: 5'-TGCCATAACTGTTCGTACTGGCAAATTGCC-3' 3'-ACGGTATTGACAAGCATGACCGTTTAACGG-5' b. The mutation altered the sequence of the wild type template DNA such that a degenerate codon for a basic amino acid in the wild type was converted to a non-degenerate codon resulting in the sequence for the mutant strand shown. What was the original amino acid? c. Compare the charges and pl of the mutant peptide and the normal (wild- type) peptide at physiological pH?
An investigator was interested in studying UAG nonsense suppressor mutations in bacteria. In one speciesof bacteria, she was able to select two different mutants of this type, one in a tRNATyr gene and the otherin a tRNAGln gene, but in a second species, she wasnot able to obtain any such nonsense suppressor mutations, even after very extensive effort. What couldexplain the difference between the two species?
Predict the amino acid sequence produced during translationof the short theoretical mRNA sequences below. (Notethat the second sequence was formed from the first by a deletionof only one nucleotide.) What type of mutation gave rise tosequence 2? Sequence 1: 5'@AUGCCGGAUUAUAGUUGA@3' Sequence 2: 5'@AUGCCGGAUUAAGUUGA@3'
Some molecules found in foods are known to be capable ofdriving DNA methylation or DNA demethylation. For example,folic acid (a vitamin), vitamin B12, and choline are thought toincrease methylation. Based on this consideration, why wouldit be important to avoid eating excessive quantities of suchmolecules (while being certain to eat sufficient quantities forhealth)?