Epigenetics (WJEC A-level biology)

This lesson describes how epigenetics is the control of gene expression by factors other than changes in the DNA sequence. The PowerPoint and accompanying resources have been planned to cover the content of point (h) from topic 3 of A2 unit 4 of the WJEC A-level biology specification.

As shown in the cover image, the lesson began with a challenge, where the students had to recognise that the prefix epi could go before 4 terms. They will learn that this prefix means on or above in Greek meaning epigenetics can be described as factors causing changes to gene function beyond the genetic code. One of several discussion periods is used to encourage them to identify what is not involved here (i.e. gene mutations), and so, epigenetics is introduced as heritable changes in gene function without changes to the base sequence.

Moving forwards, the process of DNA methylation is introduced, and students are challenged to predict how the addition of a methyl group could inhibit transcription before they have to use their prior knowledge of key terms to complete a passage about this concept. The details of a study which considered the correlation between DNA methylation and atherosclerosis are provided to broaden their knowledge and then they have to answer questions about the study using their knowledge of content from previously covered topics.

The remainder of the lesson discusses acetylation and students will learn that the removal of acetyl groups from histones causes the chromatin to become highly condensed and prevents the transcription of the gene.