Flipped lesson 7

Epigenetics Overview

• Epigenetics refers to heritable changes in gene expression that do not involve changes to the underlying DNA sequence.
• It involves mechanisms that regulate gene activity, affecting how genes are turned on or off.

CPG Islands

• CPG islands are regions of DNA with a high frequency of cytosine and guanine nucleotides occurring adjacent to each other.
• Often found near gene promoters, these regions are important for gene regulation.

Biochemical Basis

• The biochemical basis of epigenetics is related to modifications such as DNA methylation and histone modification.
• These modifications can alter chromatin structure, thereby influencing gene expression without altering the DNA sequence.

Gene 'Switched Off' State

• A gene may be 'switched off' due to hypermethylation of its promoter region, which prevents transcription factors from binding and initiating gene expression.

X Chromosome Inactivation

• In X chromosome inactivation, one of the two X chromosomes in females is randomly inactivated to ensure dosage compensation between males and females.
• It ensures that females and males have similar gene dosage from X-linked genes.

Imprinting

• Genomic imprinting involves the differential expression of genes depending on their parental origin, where only one allele is expressed while the other is silenced.

X-inactivation Truths

• The statement that "one X chromosome is inactivated in females" is true regarding X-inactivation.
• A common misconception is that all genes on the inactive X chromosome are completely silenced, whereas some escape inactivation.

Biallelic and Monoallelic Expression

• Biallelic expression refers to the expression of both alleles of a gene, ensuring that both parental contributions are utilized in protein production.
• Monoallelic expression occurs when only one allele of a gene is expressed, commonly seen in imprinted genes and certain cases of X-inactivation.

Skewed X-inactivation in Women

• Skewed X-inactivation can lead to an overexpression or underexpression of X-linked genes, potentially contributing to varying phenotypic traits or diseases in women.

Duchenne Muscular Dystrophy (DMD)

• Duchenne Muscular Dystrophy is a genetic disorder characterized by progressive muscle degeneration and weakness, primarily affecting males due to mutations in the dystrophin gene on the X chromosome.

General Facts about Epigenetics

• Epigenetic mechanisms can influence development, differentiation, and responses to environmental factors.
• These changes can be reversible and potentially passed on to subsequent generations, impacting health and disease susceptibility.

Test your knowledge of epigenetics with this quiz. Explore the concept of heritable changes in gene expression and the impact of chemical modifications on gene sequences. Understand how epigenetics is related to chromatin confirmation and its enduring effects on cell life.