Genetics Lecture 6: Epigenetics II: Transgenerational Inheritance, Genomic Imprinting, and Detection Techniques

Vocabulary practice flashcards covering mammalian epigenetic reprogramming, transgenerational inheritance, epimutations, genomic imprinting, evolutionary hypotheses, and molecular methods for detecting epigenetic modifications.

Somatic Epigenetic Inheritance

The mitotic transmission of epigenetic marks from parent cells to daughter cells during division within an organism, enabling cell differentiation and maintenance of cell fate throughout development.

Transgenerational Epigenetic Inheritance

The transmission of epigenetic modifications and associated phenotypic states from parent to offspring through the germline (gametes) that persists across generations without altering the underlying DNA sequence.

Epigenetic Reprogramming

The genome-wide erasure and resetting of accumulated epigenetic marks that occurs twice in mammalian life cycles: during gamete formation (primordial germ cells) and in the early embryo following fertilization (preimplantation blastocyst).

Epimutation

A heritable, stable change in gene expression and phenotype that results from an epigenetic modification (such as altered DNA methylation) rather than a alteration in the primary nucleotide sequence of the DNA.

Lcyc

The gene controlling floral symmetry in toadflax (Linaria vulgaris); its epigenetic silencing by extensive DNA methylation converts the wild-type bilaterally symmetric flower into the radially symmetric peloric toadflax phenotype.

Genomic Imprinting

An epigenetic mechanism in mammals whereby a gene is expressed in a parent-of-origin specific manner, resulting in the monoallelic expression of either the maternally or paternally inherited copy while the other is silenced.

Imprinted Allele

The specific parental copy of a gene that is epigenetically silenced (turned off) and not expressed in the offspring.

Functional Hemizygosity

The genetic state characteristic of imprinted loci in which only one functional allele is expressed in a diploid organism, rendering classic concepts of genetic dominance and recessiveness inapplicable.

Imprinting Control Region (ICR)

A specialized cis-regulatory DNA sequence exhibiting allele-specific DNA methylation that coordinates and directs the parent-of-origin specific expression of an entire cluster of imprinted genes.

IGF2 (Insulin-like Growth Factor 2)

An essential fetal growth and development gene in mammals that is maternally imprinted (silenced on the maternal chromosome), meaning only the paternally inherited allele is expressed.

Parental Conflict Hypothesis

An evolutionary hypothesis explaining genomic imprinting in placental mammals, proposing that paternally expressed genes evolve to maximize maternal resource extraction for fetal growth, while maternally expressed genes evolve to conserve maternal resources.

Prader-Willi and Angelman Syndromes

Reciprocal human neurodevelopmental disorders caused by microdeletions or defects in an imprinted region on chromosome 15, occurring when the single un-imprinted, active parental allele is missing or disrupted.

Methylation-Sensitive PCR

A method used to assess DNA methylation by treating genomic DNA with a methylation-sensitive restriction enzyme prior to PCR; unmethylated recognition sites are cleaved (preventing PCR amplification), whereas methylated sites remain intact and amplify successfully.

Bisulfite Sequencing

A chemical profiling method for DNA methylation wherein sodium bisulfite converts unmethylated cytosines into uracils (read as thymines following PCR), leaving 5-methylcytosines unmodified and readable as cytosines during subsequent sequencing.

Chromatin Immunoprecipitation (ChIP)

A biochemical technique used to map histone modifications and protein-DNA interactions by chemically cross-linking protein to DNA, fragmenting chromatin, immunoprecipitating targets with specific antibodies, and purifying the bound DNA for analysis via PCR, microarray, or NGS.