Today, May 11 (second Sunday in May) it is Mother's Day. While the exact date for this day differs depending where in the world one is, the one thing all Mother's Days have in common, irrespective of the when and where they take place is that it is a celebration honouring mothers and motherhood, maternal bonds, and the influence of mothers in society. While there are many good reasons to be grateful and honour our mothers for their important contributions, there is one, perhaps less known, "gift" that every woman and man inherits from their biological mothers. An inheritance that binds the human race together and tells a story of our common ancestry.
The mitochondria is the power plant in our cells and is a key organelle involved in cellular respiration. As it happens, mitochondria contain DNA (why is a different story, but it has to do with the origins of this organelle). While the amount of DNA found in the mitochondria is small compared to the DNA found in the nucleus, mitochondrial DNA (aka mtDNA) has some rather unique properties. In contrast to nuclear DNA, mitochondrial DNA does not undergo recombination. As a result the only source of new genetic variability in mtDNA are mutations. Furthermore, in most animals, most plants and in fungi mtDNA is maternally inherited. In other words, you (independent of your sex) got your mtDNA from your mother and as a result mtDNA inheritance is non-Mendelian (remember your Punnett Square; well, it only works for determining inheritance patterns for alleles located in the nuclear DNA). As it turns out these two unique feature of mtDNA (no recombination and maternal inheritance) have many uses, for example mtDNA can be used for studying the evolutionary relationships (phylogeny) of organisms. Biologists can determine and then compare mtDNA sequences among different species and use the comparisons to build an evolutionary tree for the species examined. Mitochondrial DNA has also been used to trace human maternal lineage far (very far) back in time showing that the most recent woman from whom all living humans today descend, on their mother’s side, and through the mothers of those mothers, and so on, back until all lines converge on one female that lived approximately 100,000–200,000 years ago in East Africa. Of course there were other human females around at that time, but this is the only one whose offspring survived and reproduced giving rise to today's human population. In other words, this female is the mother of us all.
Sorry dads, while this obviously does not diminish your importance and your contributions to your children, this is one gift that only mothers can give her children. So, thanks mom!
Science classrooms are unique learning environments unlike any other classrooms. As a matter of fact, some things only happen in science classrooms. Here is a collection of event that happened in my own science classroom over the last school year. It's a growing list, so check back for updates.
Report from yours truly live-tweeting and navigating the melee at GETCA 2015 (Annual Greater Edmonton Teachers' Conference).
Can a pencil be more than just your average run of the mill pencil? The legendary Palomino Blackwing Pearl can take a student or teacher's writing to new heights. We have taken a batch of the Pearls for a spin and are blown away by how much writing and sketching can be transformed by this unassuming pencil.
Dr. Pineda's Classroom is going YouTube with the release of its first screencast on the exciting topic of calculating percents. Only time will tell if this is the start of something big and shiny or just a passing fad.
After several weeks working on setting up habitats for new classroom animals the big day finally arrived. The newest addition to our classroom include aquatic denizens in our new aquarium and a teenage bearded dragon with lots of attitude and no table manners.