Question 1

Which of the following best describes the structural organization of bacterial chromosomes compared to eukaryotic chromosomes?

Accepted Answer

Bacterial chromosomes are circular, double-stranded DNA molecules compacted into a nucleoid and associated with histone-like proteins.

Question 2

Polytene chromosomes are unique because they:

Accepted Answer

Represent paired homologs that undergo many rounds of replication without strand separation or cytoplasmic division.

Question 3

Which chemical modification of histone tails is most directly associated with activation of gene expression?

Accepted Answer

Acetylation by histone acetyltransferases (HATs)

Question 4

A mutation in the lacI gene of the lac operon results in:

Accepted Answer

Constitutive expression of the operon, regardless of lactose presence.

Question 5

Which equation correctly represents the reaction catalyzed by aminoacyl tRNA synthetase during tRNA charging?

Accepted Answer

$$\mathrm{Amino\ acid} + \mathrm{tRNA} + \mathrm{ATP} \rightarrow \mathrm{Aminoacyl\ tRNA} + \mathrm{AMP} + \mathrm{PP_i}$$

Question 6

Which of the following statements about mitochondrial DNA (mtDNA) is correct?

Accepted Answer

mtDNA is typically a double-stranded closed circle, lacks chromosomal proteins, and is inherited maternally.

Question 7

Which feature of the genetic code allows for multiple codons to specify the same amino acid?

Accepted Answer

Degeneracy

Question 8

In eukaryotic transcription, what is the function of the TATA box?

Accepted Answer

It serves as a core promoter element where transcription factors and RNA polymerase II assemble to initiate transcription.

Question 9

Which of the following best explains the effect of DNA methylation on gene expression?

Accepted Answer

DNA methylation generally represses gene expression by compacting chromatin and preventing transcription factor binding.

Question 10

Which of the following is a consequence of protein misfolding in humans?

Accepted Answer

Formation of abnormal protein aggregates linked to diseases such as Alzheimer's and Parkinson's

Question 11

Which equation represents the formation of a peptide bond between two amino acids?

Accepted Answer

$$\mathrm{Amino\ acid}_1 + \mathrm{Amino\ acid}_2 \rightarrow \mathrm{Dipeptide} + \mathrm{H_2O}$$

Question 12

Which of the following is a function of the Shine–Dalgarno sequence in bacterial translation?

Accepted Answer

It base pairs with 16S rRNA to facilitate initiation of translation.

Question 13

Which of the following best describes the role of enhancers in eukaryotic gene regulation?

Accepted Answer

Enhancers are cis-acting elements that increase the rate of transcription and can confer tissue-specific expression.

Question 14

Which of the following statements about alternative splicing is correct?

Accepted Answer

Alternative splicing allows a single gene to produce multiple protein isoforms with different functions.

Question 15

Which of the following is a key difference between gene regulation in bacteria and eukaryotes?

Accepted Answer

Bacterial gene regulation is primarily linked to metabolic need, while eukaryotic gene regulation occurs at multiple levels including chromatin structure and RNA processing.

Question 16

Which of the following best describes the function of the CAP-cAMP complex in the regulation of the lac operon?

Accepted Answer

It stimulates transcription of the lac operon in the absence of glucose by facilitating RNA polymerase binding.

Question 17

Which of the following is a real-world application of genomics and bioinformatics?

Accepted Answer

Predicting amino acid sequences and deducing evolutionary relationships between genes.

Question 18

Which of the following statements about the Human Genome Project is correct?

Accepted Answer

The Human Genome Project revealed that less than 2% of the genome codes for proteins and that there are about 20,000 protein-coding genes.

Chromosome Structure, DNA Organization, and Gene Expression

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