Tutorial3.13 Quiz

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The mechanisms involved in siRNA and miRNA share some fundamental similarities despite their unique roles. What component/characteristic below is not directly involved in both siRNA and miRNA mechanisms of action?

• A) Argonaute Protein
• B) RISC Complex
• C) Dicer Protein
• D) Imperfect target sequence binding
• E) ~20 nucleotide long fragments

Methylase is an enzyme that acts during the process of restriction modification immunity. What would be the result if methylase underwent a loss of function mutation?

• A. The restriction enzyme would not be able to recognize the bacteriophage DNA and would not cut its phage DNA
• B. The bacterial cell would be unable to inject its DNA into the bacterial cell to propagate its phage cells
• C. The structural integrity of the cell wall of the bacteria will be significantly decreased without methylase
• D. The genomic DNA would be cut up at sites recognized by the restriction enzyme as a result of not being methylated
• E. The bacteriophage would be able to inject its DNA directly into the genomic DNA of the bacteria

In the study of unicellular organisms, what would be the most relevant expect molecular implication (if any exist), if there was a deletion mutation of the Dicer gene?

• Loss of mRNA polarity
• Accumulation of miRNA precursors
• Loss of pre-miRNA
• Overproduction of siRNA and miRNA
• None of the above

What would happen if there was a mutation that resulted in the absence of a PAM sequence in the phage DNA?

• Cas would not be able to bind and cut up fragments of the DNA inevitably disrupting the CRISPR-Cas9 system
• CRISPR-Cas9 system would become more efficient and target the phage better
• There would be no change that would occur to the Cas9 system
• The Cas enzyme would target another region of the phage DNA and cut it up into fragments
• A fragment of the phage DNA would be inserted into the genomic DNA

Which of the following describes the main difference between forward and reverse genetics?

• A) Forward genetics starts with a known gene to understand its effects on traits, while reverse genetics starts with a known trait to identify the responsible gene.
• B) Forward genetics begins with altering gene expression, while reverse genetics focuses on observing natural variations.
• C) Forward genetics uses DNA transformation, while reverse genetics uses RNA-mediates methods.
• D) Forward genetics studies gene functions, while reverse genetics studies phenotypical traits.
• E) None of the above

Which of the following statements best describes complementation in genetics?

• 1) Complementation occurs when two parents with homozygous dominant alleles produce offspring with a mutant phenotype.
• 2) Complementation takes place when two parents with homozygous recessive mutations on the same allele produce offspring with a wild-type phenotype.
• 3) In complementation, heterozygous offspring exhibit a mutant phenotype when mutations are allelic.
• 4) Complementation refers to the production of mutant offspring when two parents with heterozygous alleles are crossed.
• 5) Complementation refers to a genetic process when two organisms with different homozygous recessive mutations that produce the same mutant phenotype have offspring that express the wild-type phenotype when mated or crossed.

Which statement about forward and reverse genetics is incorrect?

• Researchers mutate a plant species and isolate individuals with increased herbicide resistance. This is an example of forward genetics.
• Reintroducing DNA is a common practice for most reverse genetic approaches
• Forward genetics typically starts with a phenotype and aims to identify the gene responsible for it
• CRISPR-Cas9 is commonly used in forward genetics
• Transposons and site specific recombination are common aspects of reverse genetics

Which statement best describes the differences between miRNA and siRNA?

• A) miRNAs are processed from long double-stranded RNA precursors, while siRNA are processed from hairpin-shaped RNA structures.
• B) miRNAs generally bind to perfectly complementary sequences in target mRNAs, leading to their degradation, while siRNAs bind to multiple mRNAs due to imperfect complementary and inhibit translation
• C) miRNAs play key roles in defending against viral infections by degrading viral RNA, while siRNAs are primarily involved in regulating developmental and metabolic processes.
• D) miRNAs often target multiple mRNAs due to imperfect complementarity to inhibit translation.While, siRNAs have a high degree of complementarity with their target mRNA and typically lead to mRNA cleavage and degradation.
• E) none of the above