Q.1 What is the primary mechanism by which epigenetic changes alter gene expression?
Changing the DNA sequence
Modifying histones and DNA methylation
Altering mRNA sequence
Deleting genes
Explanation - Epigenetic changes regulate gene expression without altering the DNA sequence, mainly via histone modifications and DNA methylation.
Correct answer is: Modifying histones and DNA methylation
Q.2 DNA methylation typically occurs on which nucleotide?
Adenine
Cytosine
Guanine
Thymine
Explanation - DNA methylation commonly occurs at cytosine residues, especially in CpG dinucleotides, leading to gene silencing.
Correct answer is: Cytosine
Q.3 Which of the following is an example of a histone modification?
DNA mutation
Histone acetylation
mRNA splicing
Chromosome duplication
Explanation - Histone acetylation is a post-translational modification that typically opens chromatin structure, promoting transcription.
Correct answer is: Histone acetylation
Q.4 Epigenetic changes can be influenced by:
Diet and environment
Only genetic mutations
DNA replication errors
mRNA stability
Explanation - Environmental factors such as nutrition, stress, and toxins can influence epigenetic modifications, affecting gene expression.
Correct answer is: Diet and environment
Q.5 Which enzyme adds methyl groups to DNA?
DNA polymerase
DNA methyltransferase
Histone deacetylase
RNA polymerase
Explanation - DNA methyltransferases catalyze the transfer of methyl groups to cytosine residues in DNA, affecting gene expression.
Correct answer is: DNA methyltransferase
Q.6 Genomic imprinting is an example of:
Mutation
Epigenetic regulation
Transcription factor activity
Recombination
Explanation - Genomic imprinting involves parent-of-origin-specific gene expression regulated by DNA methylation and other epigenetic mechanisms.
Correct answer is: Epigenetic regulation
Q.7 Which histone modification is generally associated with gene activation?
Histone methylation
Histone phosphorylation
Histone acetylation
DNA methylation
Explanation - Acetylation of histone tails neutralizes positive charges, loosening chromatin and allowing transcription.
Correct answer is: Histone acetylation
Q.8 Which type of RNA is often involved in epigenetic gene silencing?
mRNA
tRNA
microRNA
rRNA
Explanation - MicroRNAs can bind target mRNAs to inhibit translation or induce degradation, contributing to epigenetic regulation.
Correct answer is: microRNA
Q.9 Epigenetic changes are generally:
Permanent and unchangeable
Reversible and dynamic
Caused only by mutations
Always inherited
Explanation - Epigenetic modifications can be added or removed in response to environmental signals and developmental cues.
Correct answer is: Reversible and dynamic
Q.10 Which of the following diseases is strongly linked to epigenetic dysregulation?
Sickle cell anemia
Cancer
Cystic fibrosis
Hemophilia
Explanation - Aberrant DNA methylation and histone modifications can lead to activation of oncogenes or silencing of tumor suppressor genes.
Correct answer is: Cancer
Q.11 Histone deacetylases (HDACs) generally:
Activate gene transcription
Silence gene expression
Mutate DNA sequences
Increase mRNA stability
Explanation - HDACs remove acetyl groups from histones, tightening chromatin structure and repressing transcription.
Correct answer is: Silence gene expression
Q.12 Which term describes heritable changes in gene expression without changes in the DNA sequence?
Genetic mutation
Epigenetics
Transcription
Translation
Explanation - Epigenetics refers to heritable modifications in gene activity that do not involve changes in the nucleotide sequence.
Correct answer is: Epigenetics
Q.13 Which diet-related factor can affect DNA methylation patterns?
Folate levels
Calcium intake
Vitamin D only
Sodium intake
Explanation - Folate is a key methyl donor for DNA methylation, influencing gene expression and epigenetic regulation.
Correct answer is: Folate levels
Q.14 X-chromosome inactivation in females is an example of:
Genetic mutation
Epigenetic regulation
Chromosomal deletion
Gene duplication
Explanation - X-chromosome inactivation involves DNA methylation and histone modifications to silence one X chromosome in females.
Correct answer is: Epigenetic regulation
Q.15 Which of the following can reverse DNA methylation?
DNA polymerase
TET enzymes
Histone acetylase
RNA polymerase
Explanation - TET enzymes oxidize methylcytosine, initiating active DNA demethylation and restoring gene activity.
Correct answer is: TET enzymes
Q.16 Which of these is NOT a common epigenetic mechanism?
DNA methylation
Histone modification
Non-coding RNA regulation
Frameshift mutation
Explanation - Frameshift mutations alter DNA sequences directly and are genetic, not epigenetic, changes.
Correct answer is: Frameshift mutation
Q.17 Environmental stress can influence epigenetic patterns through:
Mutations in coding regions
Alteration of DNA methylation and histone marks
Changes in tRNA structure
Chromosome number alteration
Explanation - Stress can modify epigenetic marks, affecting gene expression without changing the DNA sequence.
Correct answer is: Alteration of DNA methylation and histone marks
Q.18 Which of the following is a known effect of histone methylation?
Always activates transcription
Always silences transcription
Can either activate or repress transcription depending on the site
Degrades mRNA
Explanation - Histone methylation effects depend on which residues are modified; some promote transcription, others repress it.
Correct answer is: Can either activate or repress transcription depending on the site
Q.19 Which epigenetic mechanism is commonly targeted in cancer therapy?
DNA replication
DNA methylation and histone deacetylation
Spliceosome activity
Chromosomal translocations
Explanation - Drugs like HDAC inhibitors and DNA methyltransferase inhibitors reverse aberrant epigenetic silencing in cancer cells.
Correct answer is: DNA methylation and histone deacetylation
Q.20 Non-coding RNAs such as lncRNAs can:
Code for proteins
Regulate gene expression epigenetically
Directly alter DNA sequence
Replicate DNA
Explanation - Long non-coding RNAs (lncRNAs) interact with chromatin and proteins to regulate gene expression without changing DNA sequence.
Correct answer is: Regulate gene expression epigenetically
Q.21 Which of the following statements about epigenetic inheritance is true?
Epigenetic marks are never passed to offspring
Some epigenetic marks can be inherited across generations
DNA sequence changes are necessary for inheritance
Only mutations cause inheritance
Explanation - Certain epigenetic modifications, like DNA methylation, can be transmitted to offspring, influencing gene expression.
Correct answer is: Some epigenetic marks can be inherited across generations
Q.22 The 'histone code' hypothesis suggests that:
DNA sequence alone determines gene expression
Combinations of histone modifications regulate gene expression
All histones are identical
RNA polymerase modifies histones
Explanation - The histone code proposes that specific patterns of histone modifications convey regulatory information for transcription.
Correct answer is: Combinations of histone modifications regulate gene expression
Q.23 Which type of epigenetic therapy is FDA-approved for some cancers?
DNA methyltransferase inhibitors
Histone acetylase activators
RNA polymerase inhibitors
CRISPR-Cas9 editing
Explanation - Drugs like azacitidine inhibit DNA methyltransferases, reactivating silenced tumor suppressor genes in certain cancers.
Correct answer is: DNA methyltransferase inhibitors
Q.24 Which of the following is true regarding epigenetic drugs?
They permanently change DNA sequence
They modify chromatin structure and gene expression
They only target mRNA
They induce frameshift mutations
Explanation - Epigenetic drugs act by reversing abnormal chromatin modifications, altering gene activity without changing the underlying DNA.
Correct answer is: They modify chromatin structure and gene expression