Concept explainers
Many human genes are known to have homologs in the mouse genome. One approach to investigating human hereditary disease is to produce mutations of the mouse homologs of human genes by methods that can precisely target specific
a. Numerous studies of mutations of the mouse homologs of human genes have yielded valuable information about how gene mutations influence the human disease process. In general terms, describe how and why creating mutations of the mouse homologs can give information about human hereditary disease processes.
b. Despite the homologies that exist between human and mouse genes, some attempts to study human hereditary disease processes by inducing mutations in mouse genes indicate there is little to be learned about human disease in this way. In general terms, describe how and why the study of mouse gene mutations might fail to produce useful information about human disease processes.
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Genetic Analysis: An Integrated Approach (2nd Edition)
- 1). In the absence of this enzyme, a substance called ceroid lipofuscin accumulates in lysosomes in the brain, resulting in seizures, blindness, decline in cognitive function and motor skills, dementia, and death by the late teens or early 20’s. The TPP1 gene is 6695 bp in length. Think about the characteristics of Batten disease, and then suggest an approach to gene therapy that might be effective for this specific genetic disorder. You may assume that your research team is working in the U.S. and your research is funded by a grant from the National Institutes of Health (NIH). Other scientists have suggested that it might be possible to use CRISPR to treat this genetic disorder in affected individuals. (i) First, what is CRISPR? (BRIEFLY describe what it is and how it works). (ii) Briefly describe how CRISPR could be utilized in treating genetic conditions such as Batten disease.arrow_forwardMutations within the genes for ARSs, are known to be cause certain human maladies, such as the neurodegenerative disorder Charcot-Marie-Tooth (CMT) disease along with other central nervous system dysfunctions, and cancer. Interestingly, not all those who possess mutations within specific ARS genes do not display the disease phenotype. Provide at least one reason why a person might survive. Remember, do not just name a concept. Describe the concept and then explain WHY (on a molecular level) this explanation holds true.arrow_forwardAn example sequence corresponds to human sickle cell beta-globin mRNA and that this disease results from a point mutation in the β globin gene. In the following section, you will compare sickle cell and normal β globin sequences to reveal the nature of the sickle cell mutation at the protein level. To do this you need to find at least one sequence representing the normal beta globin gene. Open a new window and visit the NCBI home page(http://www.ncbi.nlm.nih.gov) and select “Nucleotide” from the drop menu associated with the top search box. Then enter the search term: HBB . Note that lots of irrelevant results are returned so let's apply some “Filters” (available by clicking in the left-hand sidebar) to focus on RefSeq entries for Homo sapiens. Remember that we are after mRNA so we can compare to the mRNA sequence from part 1 above. QUESTION #1: What is the ACCESSION number of the “Homo sapiens hemoglobin, beta (HBB), mRNA” entry? NOTE: Boolean operators (NOT, AND, OR) as…arrow_forward
- It has been noted that most transposons in humans and other organisms are located in noncoding regions of the genome regions such as introns, pseudogenes, and stretches of particular types of repetitive DNA. There are several ways to interpret this observation. Describe two possible interpretations. Which interpretation do you favor? Why?arrow_forwardDNA hypermethylation (an excess of methylation) is associated with many neurological disorders, including a potential role in Alzheimer's disease. a. When comparing individuals with and without Alzheimer's, which of the following 'omics techniques (exome sequencing, whole genome sequencing, transcriptomics, or proteomics) would you expect to be the most informative if your goal is to locate potentially causative methylation differences? Briefly justify your answer. b. The pdCas9-Tet1-CD enzyme (Xu et al Cell Discov. 2016) fuses an enzyme that can carry out cytosine demethylation to a mutant version of the CRISPR/Cas9 enzyme that localizes to DNA using a guide RNA in exactly the same manner as we discussed in class for standard Cas9, except that this version does not cut the genome. This demethylase enzyme can then act to remove DNA methylation proximal to where it is stably bound. Imagine that you have identified a gene that is hypermethylated specifically in patients with Alzheimer's…arrow_forwardHuntington’s disease is a hereditary central nervous system disorder characterized by tandem repeats of the sequence 5'-CAG-3' in the gene that encodes a protein called huntingtin. The disease is progressive from generation to generation, meaning that in later generations the number of CAG repeats increases and the age of onset of symptoms decreases. Refer to Figure 21.4 and describe the sort of evidence supporting the generational increase in the number of CAG repeats.arrow_forward
- Scientists have observed that individuals with LOW birthweight are MORE likely to become obese as teenagers. To study this observation in more depth, a scientist compared the methylation of the promoter region of the leptin gene in low birthweight (LBW) and normal birthweight (NBW) individuals by treating isolated DNA from these individuals with bisulfite and comparing the results to untreated DNA. The results are shown below. What conclusion can you draw? Untreated: ATTCGATTCGCGAA Treated NBW: ATTCGATTCGCGAA Treated LBW: ATTTGATTCGTGAA Scientists have observed that individuals with LOW birthweight are MORE likely to become obese as teenagers. To study this observation in more depth, a scientist compared the methylation of the promoter region of the leptin gene in low birthweight (LBW) and normal birthweight (NBW) individuals by treating isolated DNA from these individuals with bisulfite and comparing the results to untreated DNA. The results are shown below. What…arrow_forwarda. Describe two ways you could potentially make atransgene that would inhibit the function of a specific gene in a transgenic organism. (Hint: For oneof these techniques, recall the discussion of RNAinterference in Chapter 17.)b. Discuss how you could use either of these methodsto construct a mouse model for a recessive humangenetic condition associated with a loss of function, such as cystic fibrosis.arrow_forwardGenes with highly similar sequence are often located adjacent one another in the genome. Gene duplication commonly arises from errors in replication. When the organization of such adjacent genes is in an inverted orientation, this can reduce the expression of other genes that have similar sequence and are located on other chromosomes. Explain the mechanism of how this generally occurs. Please state the answer in details: what is the mechanism? How it happens? Why this happens? When it happens? And every other necessary information.arrow_forward
- The table below shows different types of mutations in different positions in four genes. Choose the letter (A to E), from the drop-down menu, that represents the most likely type of protein that will be produced from each of these mutated genes. A: completely normal protein B: functional protein with ONE amino acid different from normal C: non-functional protein with ONE amino acid different from normal D: non-functional protein with MANY amino acids different from normal E: no protein at all Answer Type of mutation Position of mutation in gene (A, B, C, D, or E) before the part of the gene that specifies the active site of the enzyme 2 base pair insertion Inonsense immediately before the stop codon in the part of the gene that specifies the active site of the enzyme silent 1 base pair insertion in an intronarrow_forwardThe accompanying photo shows a sequencing gel from the original study that first sequenced the cystic fibrosis gene (J. R. Riordan et al. 1989. Science 245:1066–1073). From the photo, determine the sequence of the normal copy of the gene and the sequence of the mutated copy of the gene. Identify the location of the mutation that causes cystic fibrosis. (Hint: The CF mutation is a 3-bp deletion.)arrow_forwardUsing sickle-cell anemia as an example, describe what is meant by a molecular or genetic disease. What are the similarities and dissimilarities between this type of a disorder and a disease caused by an invading microorganism?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning