Quiz_section 013

Congratulations! You have discovered a new organism and have sequenced its singular strand of double-stranded DNA. Interestingly, this organism has no DNA repair mechanisms yet it still exists. You are keeping your DNA sample in a cabinet with all of your other genetics supplies, including your mutagens. Unfortunately, you knock the cabinet over and an unknown mutagen manages to contaminate your sample. When you sequence the contaminated sample DNA after one replication cycle, you notice that you now have two strands of DNA with the following sequences: ACGTAG and ACGTAG TGACTC TGCATC The original sequence, which you had recorded on your computer, was: ACGTAG TGCATC What contaminated your sample?

• Base analogs
• Hydroxylamine
• Nitrous acid
• Oxidative radicals
• Intercalating agents

A scientist is studying two genes, that are involved in cell cycle regulation. The following mutations are observed in tumor cells: Mutation A (gene 1): Results in a gain-of-function, causing excessive cell division even in the absence of growth signals. Mutation B (gene 2): Results in a loss-of-function, preventing the cell from stopping division when DNA damage is detected. Further analysis shows that one normal copy of gene 1 is enough to maintain cell cycle control, but when both copies are mutated, uncontrolled division occurs. Which of the following best classifies gene 1 and gene 2 before mutation, and their roles in cancer development?

• gene 1 is a proto-oncogene that became an oncogene; gene 2 is a tumor-suppressor gene following the two-hit hypothesis.
• gene 1 is a tumor-suppressor gene that became an oncogene; gene 2 is a proto-oncogene that follows the two-hit hypothesis.
• gene 1 is an oncogene from the start; gene 2 is a tumor-suppressor gene that follows haploinsufficiency.
• gene 1 is a proto-oncogene that became an oncogene; gene 2 is a tumor-suppressor gene but does not follow the two-hit hypothesis.
• genes 1 and 2 are both tumor suppressor genes, following the two-hit hypothesis

A pythons genomes, which is double stranded, is approx 1,400,000,000 bases long. You have the sequence ACGTTCGGACTA. Assuming an equal ratio of A, T, G, C in the genome, how many times would you expect this sequence to occur randomly?

• 143
• 167
• 223
• 159
• 8

The MIT gene is a made-up gene that is present in all bacteria and is associated/involved in signaling the bacteria to undergo mitosis/cell division. Scientists observe that cancerous cells tend to be much smaller than regular cells and divide much more quickly because of a mutation to this gene that forms a new allele. When looking at the cancer cell, the MIT levels/number of protein and transcript are at their normal levels. Fill in the sentence: The mutated MIT allele is likely ____ at the ____ level of gene expression, meaning that it is a _____ allele and a _____.

• Upregulated; translational; gain-of-function; tumor-suppressor gene
• Upregulated; splicing; gain-of-function; oncogene
• Downregulated; transcriptional; loss-of-function; tumor-suppressor gene
• Upregulated; translational; gain-of-function; oncogene
• Upregulated; post-translational (protein activity); gain-of-function; oncogene

In a bacterial strain with the genotype I⁺ Oᶜ Z⁺/I⁺ O⁺ Z⁻, which of the following statements best describes the expected phenotype regarding beta-galactosidase production

• A) Beta-galactosidase is only expressed when lactose is present.
• B) Beta-galactosidase is never expressed due to the presence of a loss-of-function mutation.
• C) Beta-galactosidase is expressed only in the absence of glucose, but not in the presence of lactose.
• D) Beta-galactosidase is never expressed.
• E) Beta-galactosidase is constitutively expressed, regardless of lactose presence.

When sequencing the genome of a unicorn, you have generated a total of 5 000 000 reads, each being 105 base pairs long. The unicorn's genome is 40 000 000 base pairs long. How many bases within the genome were not sequenced?

• 65
• 80
• 100
• 87
• 1

Which of the following is a key characteristic of PacBio sequencing?

• It relies on chain-termination using fluorescently labeled dideoxynucleotides.
• It generates very short reads with high accuracy.
• It utilizes single-molecule, real-time sequencing to produce long reads.
• It primarily focuses on detecting specific target sequences using hybridization.
• It amplifies DNA through bridge PCR on a solid surface before sequencing.