QUiz_section 024

A researcher is interested in studying genes involved in muscle development in zebrafish. They randomly induce mutations using a chemical mutagen and then screen for fish with abnormal muscle structure. After identifying mutants, they use genetic mapping to determine which genes are responsible for the phenotype. Which type of genetic approach is the researcher using?

• A) Forward genetics, because the experiment starts with a known gene and investigates its function.
• B) Reverse genetics, because the experiment starts with a known gene and investigates its function.
• C) Neither forward nor reverse genetics, because the mutations were induced randomly.
• D) Both forward and reverse genetics, because the researcher studies both genes and phenotypes.
• E) Forward genetics, because the experiment starts with a phenotype and then identifies the genes responsible.

In which of the following will beta-galactosidase be produced only when lactose is present?

• A: Is o+ Z+ / I- oc Z+
• B: I+ oc Z- / I+ o+ Z+
• C: I- o+ Z- / I- oc Z-
• D: I+ oc Z+ / I- o+ Z-
• E: Is oc Z- / I+ o+ Z+

Which statement accurately describes a characteristic of eukaryotic enhancers?

• They must be adjacent to the promotor they regulate
• They require direct contact with RNA polymerase to function
• They can enhance transcription from a distance, regardless of orientation
• They are always located within the coding region of the gene they regulate
• They only function in prokaryotic cells

A researcher is sequencing a eukaryotic genome that contains many repetitive regions. They initially used Illumina sequencing but struggled with correctly assembling these repetitive sequences. What would be the best sequencing strategy to resolve these repeats, and why?

• Increase the number of reads in Illumina sequencing to ensure higher coverage
• Use PacBio or Nanopore sequencing to obtain longer reads
• Shorten the read length in Illumina sequencing to improve base accuracy
• Use Sanger sequencing for its high accuracy despite its short read lengths
• Increase the number of adaptors to improve DNA fragment binding

At what level of gene expression is HB mRNA regulated when 4EHP is involved? 4EHP is involved in a complex that can bind to the 5’ cap of HB mRNA.

• Transcriptional regulation, as 4EHP prevents RNA polymerase from binding to DNA.
• Splicing regulation, as 4EHP alters the mRNA sequence before translation.
• Translational regulation, as 4EHP prevents the mRNA from being translated into protein.
• Post-translational regulation, as 4EHP modifies the protein after it is made.
• Translational regulation, as 4EHP allows the mRNA to be translated into protein.

What event likely triggered the endosymbiosis of bacteria into ancestral eukaryotic cells ~1 billion years ago?

• The rise of photosynthetic algae that produced oxygen
• The advantage of ancestral cells which incorporated bacteria that utilized aerobic glycolysis.
• The advantage of bacterial genes that permitted growth under low oxygen conditions.
• None of the above
• All of the above

A researcher is studying a genetic disorder caused by mutations in the PAX6 gene, which is involved in eye development. Individuals who are heterozygous for a loss-of-function mutation in PAX6 develop aniridia (absence of the iris), while homozygous individuals for the mutation exhibit severe eye defects and early lethality. What does this suggest about the inheritance pattern of the PAX6 gene?

• Haplosufficient, because one functional copy of PAX6 can compensate for the loss of the other.
• Haploinsufficient, because one functional copy is not enough to maintain the normal phenotype, leading to a dominant disorder.
• Gain-of-function, because the mutation enhances PAX6 activity, resulting in eye malformations.
• D) Recessive loss-of-function, because the phenotype only appears in individuals who are homozygous for the mutation.