In another life, I taught high school biology and had a lot of fun doing it. I had my students do the Cell City when we worked with organelles in the cell, and once we got to the genetics unit, we did something fun called Dragon Genetics. In this activity, students would pair up (one was the mommy dragon, the other the daddy dragon) and throw “chromosome” sticks to see what traits they would “pass on” to their theoretical dragon baby. The activity is quite simple once students understood basic Mendelian genetics (and some of the non-Mendelian patterns as well), and even my son was able to draw his own dragon baby when I had him be my guinea pig while he was still in elementary school. (Figure 1) There were some amazingly creative dragons adorning my classroom, and I hope you can share the Dragon Genetics activity with any teacher friends as we discuss non-Mendelian traits and disease here. As we celebrate the beautifully-designed experiments by Gregor Mendel that led to the modern study of genetics and genomics, we might also be reminded that patterns of inheritance, like many things in life, are far from binary.

Foreword

To start, put yourself in a hypothetical situation: you have an identical twin brother who was secretly transferred to another family when you were less than a year old. His new family was poor, and your family was rich and therefore the environment in which you grew up was much better than his. After 50 years, by chance, you both happen to meet and it turns out that you look quite different from one another and are in different states of health; he is short and is suffering from heart disease, while you are tall, healthy, and are training to run a marathon. So, what was it that made you two so different, in light of the fact that your genetic materials are completely identical?

Anyone who is remotely interested in biology, or has perhaps scrolled through fitness websites to get in shape, has come across the word "protein". There is, however, much more to proteins than simply being a key player in maintaining active lifestyles. Proteins are ubiquitous in the cells of the body and are the driving force for key cellular processes. In order for proteins to carry out their duties, they need to be well-armed to execute their functions. This process of making the protein competent is achieved through specific post translational modifications (PTMs). The star of the PTMs is a cellular process called phosphorylation. The conventional methods adopted for quantifying phosphorylation are highly labor intensive. The development of phospho-specific antibodies has allowed for a huge sigh of relief from researchers due to their reputation of being quick, and detecting only phosphorylated forms of proteins in a complex mixture of phosphorylated and non-phosphorylated forms.

The Hippo signal is very conservative in evolution. It regulates organ size and tissue stability by regulating cell proliferation, apoptosis, and stem cell renewal. The core process of Hippo signaling is a kinase tandem process, Mst1/2 and Sav1 form a complex, phosphorylate and activate Lats1/2; Lats1/2 kinase then phosphorylates and inhibits transcriptional coactivators Yap and Taz. Yap and Taz are the most important effectors downstream of the Hippo pathway. Upon dephosphorylation, Yap and Taz translocate to the nucleus and interact with TEAD1-4 or other transcription factors (such as CTGF) to induce gene expression, thereby initiating cell proliferation and inhibiting apoptosis.

Long-interspersed nuclear elements (LINEs) are genetic components found in higher eukaryotes. They are retrotranposons, meaning that they are transcribed into mRNA and then translated into proteins that act as a reverse transcriptase. The reverse transcriptase makes a copy of the LINE DNA which can then be integrated into the genome at a new site. The only active LINE in humans is LINE-1. It has been associated with oncogenesis and Haemophilia A, a diseased caused by insertional mutagenesis.

DNA methyltransferase (DNMT) is an important family of enzymes that catalyze and maintain DNA methylation, a common marker in the epigenetic silencing of target genes. The enzymes play a key role in the regulation of gene expression and genomic imprinting/development.