Genetic Manipulation: The direct manipulation of one or more genes

This is an MCQ-based quiz for GRE on the topic of Genetic Manipulation.

This includes DNA isolation, Gene cloning, Gene design, Transformation, and Plant breeding.

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Which of the following is not a methodology to obtain either transient or stable knockout/ knockdown of a gene?

Morpholino shRNA interference Crispr-Cas9 Homologous recombination GAL4-UAS system

Genetically altering an animal to reduce the expression of a gene of interest can be a labor intensive process that does not necessarily produce complete loss of a gene. A genetic null is an animal in which the gene has been completely (or nearly completely) excised and as such, no protein is produced. A genetic hypomorph is an animal in which only part of a gene has been deleted and as such, a lower amount of protein or a dysfunctional protein is produced, but it is still there. Hypomorphs can be close to null, perhaps only retaining 5-10% of normal function, or they can be close to wild-type, retaining 80-90% of gene function and having mild mutant phenotypes. You are studying Gene H, a gene that regulates head size, and the more Gene H is expressed, the larger the organism"s head is. You have one animal that is null for Gene H, and one that is a hypomorph for Gene H. You compare the head sizes of these animals. Which of the following results is least likely to be true from your experiment? You can assume that a wild-type animal will have the largest head size of the three.

Both the null and hypomorph have smaller heads than the wild-type, and the null is smaller than the hypomorph, but only by about 5%. The null and the hypomorph have roughly the same head size, because the hypomorph is dysfunctional enough to disturb head size development. The null has a larger head than the hypomorph by about 10%. The null and the hypomorph cause smaller head size early in development, but the hypomorph head growth accelerates later in development. Both the null and hypomorph have smaller heads than the wild-type, but the null is the smallest by a very large factor, nearly 90% smaller than the hypomorph.

Which of the following techniques could help a researcher inhibit the expression of a target gene?

FPLC qPCR X-ray crystallography RNAi

Which of the following statements best describes the function of RNAi?

Interfere with translation by targeting specific tRNA molecules Globally interfere with translation by blocking all mRNA Interfere with translation by targeting ribosomes Interfere with translation by blocking a target mRNA

Which protein, associated with the RNA-inducing silencing complex (RISC), activates and cleaves mRNA in RNAi?

None of these RNA helicase Endonuclease Argonaute RNase III Dicer

Double stranded DNA Single stranded RNA DNA-protein complex Single sheet polypeptide Double stranded RNA

Many strains of the model organism Drosophila have been engineered to express RNAi transgenes; that is, these transgenes express a moiety that is capable of targeting specific mRNAs to be degraded. This effectively results in downregulation of certain genes, permitting scientists to study how loss of that gene effects the organism. Consider the following hypothetical situation. Gene A codes for the protein Enzyme A; that is, Gene A is expressed and is translated to make Enzyme A. You obtain a fly expressing an RNAi that targets Gene A"s mRNA. If you express this RNAi in a fly (Drosophila), which of the following is the most likely result you"d expect if you were able to monitor Enzyme A levels with a fluorescent antibody and compared a wild-type fly to one expressing the RNAi?

Enzyme A levels would be reduced in the RNAi expressing fly, resulting in less fluorescence in the RNAi expressing fly. Enzyme A levels would be increased and more fluorescence would be apparent in the RNAi expressing fly. Enzyme A levels would be decreased in both the wild-type and RNAi expressing flies. Enzyme A levels, and therefore fluorescence, would be decreased only in the nucleus of the RNAi expressing fly because this is where translation occurs. Enzyme A levels would be unchanged because RNAi targets mRNA, thus no differences in fluorescence would be apparent between wild-type and RNAi expressing flies.

Which term describes DNA that has been altered by genes from a different organism, typically from a different species?

DNA replication DNA fingerprinting DNA-DNA hybridization Recombinant DNA DNA sequencing

A scientist seeks to synthesize a rare human protein in lab. To accomplish this, she utilizes recombinant techniques to insert the DNA of a eukaryotic gene for the protein into bacterial plasmids. These plasmids are transformed into bacteria for expression. She is disappointed to discover that the gene product from the bacteria is not the correct protein. What corrective step could she take in the procedure to fix this issue?

Ligate the gene directly into the chromosome Insert mRNA into the plasmid instead of DNA Use archaea instead of bacteria Use a different genus bacteria Use cDNA for the gene instead of DNA

Dicer is an endonuclease that cleaves __________ during the process of RNA-interference.

Double-stranded DNA

Double-stranded RNA

Single-stranded RNA

Transcription factor mRNA

Single-stranded DNA

Quiz/Test Summary

Title: Genetic Manipulation: The direct manipulation of one or more genes

Questions: 10

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