Question 1

Which of the following best describes the concept of 'junk DNA' as it has evolved in genetics research from the 1970s to the present?

Accepted Answer

Many regions previously labeled as 'junk DNA' have regulatory or structural roles, and only a minority of non-coding DNA is truly functionless.

Question 2

The lac operon in E. coli is an example of an inducible system. Which of the following statements about its regulation is correct?

Accepted Answer

Transcription of the lac operon is activated when lactose is present and glucose is absent, due to the combined action of the CAP-cAMP complex and the removal of the lac repressor.

Question 3

Which experiment would best test whether a region of DNA labeled as 'junk' has a functional role in gene regulation?

Accepted Answer

CRISPR-Cas9 deletion of the region followed by analysis of gene expression changes.

Question 4

A mutation in the operator region of the lac operon prevents the lac repressor from binding. What is the expected outcome?

Accepted Answer

Transcription of the lac operon will occur even in the absence of lactose.

Question 5

Which of the following elements in a gene are considered non-coding but essential for regulation?

Accepted Answer

Promoters and enhancers

Question 6

In eukaryotic gene regulation, what is the primary difference between cis-acting and trans-acting elements?

Accepted Answer

Cis-acting elements are adjacent to the gene they regulate, while trans-acting elements are diffusible molecules that can act at a distance.

Question 7

Which of the following best explains why bacteria prefer glucose over lactose as an energy source?

Accepted Answer

Glucose metabolism is more energy-efficient and does not require the induction of additional enzymes.

Question 8

A researcher uses F' plasmids to test lac operon model in E. coli. What is the purpose of this experiment?

Accepted Answer

To determine if a wild-type copy of a gene on the F' plasmid can complement a mutant allele on the chromosome.

Question 9

Which of the following sequences is most likely to be a consensus sequence for transcription initiation in eukaryotes?

Accepted Answer

$$	ext{TATAAA}$$

Question 10

Alternative splicing allows for:

Accepted Answer

The production of multiple protein isoforms from a single gene.

Question 11

Which of the following is true regarding the role of repetitive DNA in gene regulation?

Accepted Answer

Repetitive DNA can regulate gene expression by influencing chromatin structure and transcription factor binding.

Question 12

Which of the following best describes the function of the lacZ gene in the lac operon?

Accepted Answer

It encodes an enzyme that converts lactose to glucose and galactose.

Question 13

What is the effect of CAP (catabolite-activating protein) binding to cAMP in the regulation of the lac operon?

Accepted Answer

It promotes transcription of the lac operon by facilitating RNA polymerase binding.

Question 14

Which of the following statements about transcription termination in eukaryotes is correct?

Accepted Answer

Transcription termination involves cleavage and polyadenylation at the $$	ext{AAUAAA}$$ signal.

Question 15

A DNA sequence is given: 5'-TATACGACCAGTCCGTAA-3' (coding strand). What is the amino acid sequence starting from the first ATG?

Accepted Answer

Question 16

Which of the following is a real-world application of understanding non-coding DNA function?

Accepted Answer

Identifying regulatory mutations that cause human diseases such as cancer.

Question 17

Which of the following statements about enhancers is correct?

Accepted Answer

Enhancers can regulate transcription from a distance by looping to interact with promoter regions.

Question 18

In the context of gene regulation, what does combinatorial control refer to?

Accepted Answer

The integration of multiple transcription factors and regulatory elements to precisely control gene expression.

Question 19

Which of the following is true about the role of polyadenylation in mRNA processing?

Accepted Answer

Polyadenylation stabilizes mRNA and facilitates its export from the nucleus.

Question 20

A mutation in a trans-acting factor that binds to an enhancer region would most likely result in:

Accepted Answer

Altered expression of multiple genes regulated by that enhancer.

Gene Regulation, Non-Coding DNA, and the Lac Operon: Key Concepts in Genetics

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