AP Bio epigenetics and DNA methylation practice questions

Define epigenetics.

The study of heritable changes in gene expression without altering the DNA sequence.

True or False: DNA methylation is a permanent modification.

False. DNA methylation can be reversible and is influenced by environmental factors.

What is the role of DNA methylation?

It typically represses gene transcription by preventing RNA polymerase from accessing the DNA.

Fill in the blank: Epigenetic changes can be caused by ______.

Environmental factors, diet, stress, and aging.

Compare methylation in embryonic vs. adult cells.

Embryonic cells have less methylation; adult cells show more methylation patterns that regulate differentiation.

How does DNA methylation affect transcription factors?

Methylation can block transcription factors from binding to promoter regions, inhibiting gene expression.

What is an example of an environmental factor affecting epigenetics?

Dietary components like folate or toxins such as heavy metals can alter DNA methylation patterns.

True or False: All genes are equally affected by DNA methylation.

False. Some genes are more sensitive to methylation changes, influencing their expression significantly.

What can result from abnormal DNA methylation?

Can lead to diseases such as cancer by activating oncogenes or silencing tumor suppressor genes.

Define the term 'histone modification'.

Chemical changes to histone proteins that affect chromatin structure and gene expression.

How does demethylation occur?

Through enzymatic processes involving demethylases that remove methyl groups from DNA.

What is the connection between aging and epigenetics?

Aging can lead to global hypomethylation and site-specific hypermethylation, affecting gene expression.

Fill in the blank: The main enzymes involved in adding methyl groups are called ______.

DNA methyltransferases.

Explain the phenomenon of genomic imprinting.

Differential expression of a gene depending on whether it is inherited from the mother or father.

Define DNA methylation.

The addition of a methyl group to DNA, typically at cytosine residues, affecting gene expression without altering the DNA sequence.

True or False: DNA methylation is heritable.

True. Methylation patterns can be passed from one generation to the next, influencing gene expression in offspring.

Compare euchromatin and heterochromatin.

Euchromatin: active, loosely packed, accessible for transcription. Heterochromatin: inactive, tightly packed, less accessible.

Fill in the blank: Methylation typically occurs at the ____ base in mammals.

cytosine.

What effect does DNA methylation have on gene expression?

Generally reduces gene expression by inhibiting transcription factor binding and RNA polymerase access.

Identify a consequence of increased DNA methylation in cancer cells.

Increased methylation can lead to silencing of tumor suppressor genes, contributing to tumorigenesis.

Causation: How does environmental stress affect DNA methylation?

Environmental stress can lead to changes in DNA methylation patterns, potentially altering gene expression and phenotype.

List three factors influencing DNA methylation patterns.

1. Environmental factors 2. Age 3. Diet.

What role does the enzyme DNA methyltransferase play?

It catalyzes the transfer of methyl groups to DNA, establishing and maintaining methylation patterns.

True or False: All genes are equally affected by methylation.

False. Methylation affects gene expression variably; some genes are more sensitive to these changes than others.

Discuss the significance of CpG islands in methylation.

CpG islands are regions with a high frequency of CpG sites, often found near gene promoters, crucial for regulating gene expression.

What is the role of demethylation in development?

Demethylation is essential for gene activation during development, allowing expression of genes necessary for cell differentiation.

Explain how methylation can affect phenotype.

Methylation can silence genes, leading to changes in traits and characteristics without altering the underlying DNA sequence.

Describe the relationship between epigenetics and phenotype.

Epigenetics involves changes in gene expression and regulation, influencing an organism's phenotype without changes to the DNA sequence.