Genetics 2024 Section 12

In a forward genetic screen for maternal effect genes in Drosophila, why is the analysis delayed until the F4 generation?

• A) Maternal effect genes are not expressed until the F4 generation.
• B) The F4 generation is the earliest stage at which the phenotype becomes apparent.
• C) Maternal gene products stored in the egg are not translated until the F4 generation.
• D) The delay allows for the identification of genes important for early embryonic development.
• None of the Above

A sample of Chlamydomonas was transformed to contain a Bleomycin-resistance gene. The sample was then plated on an agar plate containing the bleomycin antibiotic, and incubated for 2 weeks. The transformed cells survived and divided into colonies. A colony exhibiting a change in phenotype (abnormally long flagella) was identified and selected. This colony was genetically screened and the location of the bleomycin-resistance insert was found to be in the LF3 gene responsible for proper flagellar growth, disrupting its function. The WT LF3 gene codes for a protein that prevents the flagella from becoming too long. What is this an example of?

• Reverse genetics; homologous recombination; gain of function.
• Forward genetics; screening; loss of function.
• Forward genetics; selection; gain of function.
• Forward genetics; selection; loss of function.
• Reverse genetics; homologous recombination; loss of function.

You are studying a gene in fruit flies critical for eye development and wing development, called EYEW. Through functional complementation, you have identified two conserved regions in the EYEW protein. In the plasmid carrying the EYEW gene, you create two mutations: the first mutation removes the first conserved region, and the second mutation removes the second conserved region. Surprisingly, the mutation in the first conserved region does not rescue the eyeless or wingless phenotype, while the mutation in the second conserved region successfully rescues eye development, but does not rescue wing development. These two mutant alleles are examples of_____.

• A. a loss-of-function allele and a dominant-negative allele
• B. two loss-of-function alleles.
• C. a gain-of-function allele and a functional allele.
• D. a loss-of-function allele and a functional allele
• E. a loss-of-function allele and a hypomorphic allele.

In a switch regulation: Signal ---> Gene A ---| Gene B ---> Gene C ---> response Based on this information, which of the following statements are correct? i. In a switch regulation, epistatic means upstream because when a mutation occurs in Gene B and Gene C, Gene B is masked by the mutation in Gene C ii. If Gene B is epistatic to Gene A, and a mutation in Gene A on its own causes an ON response, then a mutant Gene B on its own must also cause an ON response iii. The gene product of Gene A is inhibiting Gene B, this is shown through the flat ended arrow

• Only i
• Only iii
• i and iii
• ii and iii
• All 3

In a complementation analysis experiment involving leucine mutants, researchers observe two independent mutant alleles, leucine 1 and leucine 2. If these mutations are confirmed to be in the same gene, what is the likely outcome?

• A. Complementation will occur, leading to a wild-type phenotype.
• B. Complementation will not occur, resulting in a mutant phenotype.
• C. Complementation is possible, but only if a diploid configuration with leu+ is established.
• D. Complementation depends on the presence of additional mutations in other genes.
• E. None of the above

If the siRNA and miRNA (and all its components needed for RNAi were included) were isolated and blindly placed in two different solutions, how could you tell which solution was from a siRNA or a miRNA RNA interference?

• One solution contains the Dicer protein whereas the other solution does not
• The siRNA solution will have single-stranded RNA whereas the miRNA solution will have double-stranded RNA
• One solution is encoded by a specific gene in the genome whereas the other solution originated from the insertion of a plasmid
• The target RNA will be cleaved out in one solution but not the other
• There will be large fragments paired with Argonaute in one solution and small fragments paired with Argonaute in the other solution

In some cats, they develop a fur pattern that makes the patch of fur on their paws white, making them look like they are wearing 'white socks'. Lets say a specific gene 'WS' was identified to be responsible for the unique pattern in cats by supressing the expression of colour at the location of the cat's paws. You took the 'WS' to analyze and attempted to knock out 5 locations of the gene to see which part of the gene is complement for the cat's 'white socks'. The following are the phenotypes of 5 kittens (Knocking out the genes will not hurt them in anyway and they would become future adorable trouble makers/angels at nice homes). Location 1 on 'WS': Kitten had no 'white socks' Location 2 on 'WS': Kitten had no 'white socks' Location 3 on 'WS': kitten had 'white socks' Location 4 on 'WS': Kitten had no white socks' Location 5 on 'WS': Kitten had 'white socks' Which of the locations of the 'WS' is not essential for the 'WS' function?

• A. Location 1,2
• B. Location 3,4,5
• C. Location 3,5
• D. Location 1,2,4
• E. None of the above

What is the role of maternal effect genes in the development of Drosophila melanogaster?

• They determine the final adult structure of the fly.
• They are responsible for the segmentation of the embryo.
• They set up the broad anterior and posterior regions in the fruit fly embryo.
• They directly regulate the development of the eye and wing patterns in adult flies.
• They activate the zygotic genes necessary for the embryo's further development.

In which of the following situations would the forward genetics approach be the most appropriate tool for analysis?

• Studying the function of a known gene in an organism for a resulting phenotype.
• Studying the factors involved in the rate of transcription of a gene in response to external stimuli.
• Identifying the genetic mutations that have resulted in a hereditary disease without knowing the direct gene that has been mutated.
• Identifying how mutations in a gene, which could cause a gain-of-function or loss-of-function allele, alters the overall phenotype present in the organism.
• None of the above.

If two dogs that are affected by progressive retinal atrophy were crossed with one another, and the entire progeny was not affected by progressive retinal atrophy, which of the following statement is true?

• A. The two dogs had mutations in the same locus
• B. The two dogs had mutations in different loci
• C. The mutations in the two dogs are dominant
• D. You cannot tell from this information given
• .