Human Molecular Genetics Assignment 3 (Week 3)

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1 Human Molecular Genetics Assignment 3 (Week 3) Q1. Which one of the following is an effect of a genetic mutation? a. Prevent the synthesis of a normal protein. b. Alters the function of the resulting protein c. Alters the stability of the resulting mrna d. All the above A genetic mutation such as a non-sense mutation can affect the stability of an mrna as it may affect the post-transcriptional regulations necessary for mrna stability. Also, such a mutation would result in a truncated protein due to premature termination. Also, a genetic mutation such as missense can affect the function of a protein as it may change the coding frame of the protein Q2. Among the types of mutations listed below, identify the mutational type that could possibly represent a gain-of-function effect. a. Non-sense mutation b. Gene deletion c. Splicing mutation d. Missense mutation Among the listed mutations, the missense mutation is most likely to result in a gain-offunction effect as the resulting protein could acquire a novel function. The other mutations are most likely to cause loss-of-function effect. Q3. A mutation originates during meiosis while a mutation originates during mitosis. a. germ line, somatic b. germ line, spontaneous c. deletion, chromosomal d. spontaneous, point Answer: A Germ line mutations the mutations that are transmitted through generation, occur during meiosis, while somatic mutations, those that are not transmitted, occur during mitosis and their presence might be restricted a group tissue or cells. Q4. Which one of the following mutation could be present in a mutational hotspot? a. gene deletion b. point mutation c. chromosomal translocation d. all the above

2 A mutational hotspot is a region of DNA that exhibits an unusually high propensity to mutate. All the mutations listed above could fall in the hotspot. Q5. The term non-allelic homologous recombination refers to: a. recombination between two alleles of the same gene present on the homologous chromosomes b. recombination between two segments that show high sequence similarity but are located on two different chromosomes. c. recombination between two non-alleles located on the homologous chromosomes d. none of the above Non-allelic homologous recombination happens between the non-alleles of the homologous chromosomes, as a result there could be gain of some segment in one of the homologues, and loss in the other. Q6. Which of the following statements correctly define the term Founder-Effect Mutation : a. a mutation present in the DNA of an individual who discovered a new population b. mutation that appeared in the DNA of one or more individuals who are founders of a distinct population c. mutation that changed population so different from the original population, therefore the latter is now a new species. d. a mutation which serves as signature sequence to identify all individuals belonging to a specific population. Founder effect occurs when a new population is established by a very small number of individuals from a larger population. When a mutation occurs in one of the individuals founding this new population, it s called Founder-Effect Mutation. Q7. Dynamic mutations refers to a. a mutation process wherein a defect in one gene induce a defect in another gene. b. a mutational process wherein the repeating unit in a repeat locus expands in successive generation. c. a mutation that appears in a generation and disappears in the next generation. d. a mutations which manifest only in alternate generation A very special genetic mechanism whereby a run of tandemly repeated nucleotides, such as CAGCAGCAGCAGCAG, is meiotically unstable. For instance, a repeat locus with 40 CAG repeating units can expand to 80 repeat units in the next generation. Q8. Which one of the following statements accurately represents the process involved in the generation of a transgenic animal via pronuclear injection? a. Foreign RNA in all the cells. b. Foreign DNA only in the somatic cells c. Foreign DNA in all the cell d. Foreign DNA only in the germ cells

3 Generation of a transgenic animal via pronuclear injection results in the integration of the foreign DNA in all the cells of the animals. Q9. Which one of the following statements distinguishes a conditional knockout mouse from a global knockout mouse? a. a targeting construct is used to replace/modify a gene b. the targeting construct can inactivate the gene c. the gene is inactivated in a specific type of cells/organ. d. the gene is inactivated in all cells of the organism Conditional knockout technology inactivates a gene in a specific cell or tissue since the expression of the deactivation cassette is under a gene or tissue specific promoter. However, in global knockout mouse the inactivation is occurs in all cell types. Q10. The process by which the target gene is altered in a knockout mouse involves a. chromosomal translocation b. non-homologous recombination c. homologous recombination d. random genomic integration Answer C The gene of interest undergoes homologous recombination with a new DNA sequence which is very highly similar to the gene of interest and its immediate neighbor sequence are, except that the region for the gene of interest is swapped by an antibiotic resistance marker

4 Q11-Q12: the schematic give below identifies key steps in the creation knockout mice model for biomedical investigations. Based on your understanding answer the questions give below: Q11: The term foster mother refers to: a. Biological mother to the offspring born to this animal b. A pseudo-pregnant female accepting embryos of another female of the same species c. A pseudo-pregnant female accepting embryos of another female of a different species d. A mother who takes care of offspring born to another female. The genetically altered stem cells are transferred into a developing embryo that is transferred into the uterus of a mother called foster mother, and she is not the biological mother of the embryos implanted.

5 Q12: The term chimera mouse refers to: a. A mutant mouse b. A mouse born to parents belonging to two different species c. A mouse born to parents belonging to two different strains of mouse d. A mouse having some part of its tissues derived a from a source other than the biological parents A chimeric mouse is an organism that is composed of two or more different populations of genetically distinct cells that originated from different zygotes.