Epigenetics: true or false?

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Correct answers: 

2. Epigenetics modulates gene expression without modifying the genome.
5. Unlike genetics, epigenetic mechanisms are reversible.

Whereas genetics focuses on the study of genes, epigenetics is concerned with an additional “layer” of information that defines how these genes are used by a cell—or not used at all. For example, the same bee larva will develop into a queen or a worker depending on how it is fed. This is caste polyethism … which can be reversible: a worker can start laying eggs if her ovaries are no longer inhibited by queen pheromones.

After emergence, the worker first acts as a cleaner, then a nurse, a builder … and finally a forager. This is age polyethism … which can also be reversible: an old winter bee can become a nurse again at the end of January, when egg laying resumes.

Methylation is a chemical modification of DNA involving the attachment or substitution of a methyl group on certain nucleic bases. More simply, some parts of the DNA can be temporarily masked or covered (by methylation) and thus prevented from producing certain proteins/enzymes, thereby modifying the insect itself or its behavior. This involves the expression of the same overall genetic code, but environmental factors select one expression over another, each being available within the “genetic database.” In other words, epigenetics governs how the genotype is used to create a phenotype.

The genotype, or genetic heritage, refers to the full set of hereditary characteristics, whether observable or not. By contrast, the phenotype refers to the characteristics that can be observed or the appearance, such as eye color in humans.

For further reading:

►Epigenetics conducts genetics
► Introduction to bee genetics
► DNA adaptation according to role
► Epigenetics
► The bee genome
► Genetics or epigenetics
► Differentiation of bees into queens and workers: an epigenetic question