Epigenetics is a field of molecular biology that studies the changes in gene expression that are not connected to any modifications in DNA nucleotide sequence. This B. Sc. Thesis offers a review of epigenetic mechanisms (DNA methylation, histone modifications, miRNA), explains their underlying function and influence in gene expression which determines phenotype of the organism. In the thesis, we focused on epigenetic modifications of gametes and their precursors. It summarizes the course of gametogenesis, more accurately spermatogenesis, its epigenetic regulation (cell specification, eraser of imprinted genes, epigenome reprogramming, chromosome condensation) and their role in epigenome response to the changes in environment. Factors like diet, stress, herbicides/pesticides, including the developmental stage and age of the organism, temperature, lifestyle and medical condition can reflect in changed epigenetic profile and consequently in both parental and offspring phenotype. The B. Sc. Thesis summarizes direct changes in F0/Fn generation epigenome that arise as a consequence of environmental influence on the epigenetic profile, which can not be erased by germ cell reprogramming and is thus transgenerationally inherited and transmited between generations.
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