Saturday, December 17, 2011

What genetics should all our students learn? ("Stop, we're teaching the wrong stuff!")

Several years ago I was asked to take charge of developing a new second-year 'fundamentals of genetics' course, to replace our program's long-standing third-year course (a legacy from David Suzuki and Tony Griffiths).  So I put together a committee of genetics instructors (profs, sessionals, a TA), and we developed a new set of learning objectives and an ordered list of topics to be covered (a syllabus).  The committee then disbanded , leaving me to implement its work, first as a small pilot class (last winter) and then as a regular course (just finished).

We thought we had been quite radical, because we'd made a very big change in how our course would teach the two big concepts students needed to master - how genotype determines phenotype and how genetic information is inherited.  Traditional genetics courses start with Mendel, and, following in Mendel's footsteps, use analysis of crosses to reveal all the basic concepts of classical genetics; this is Suzuki's 'Genetic Analysis' approach.  Our new syllabus began not with Mendel but with three weeks about how genotype determines phenotype (no crosses yet), followed by two weeks just about how inheritance works (leaving phenotypes out entirely)  Only then would it introduce Mendelian genetics, and then use the standard genetic analysis framework to teach the more complex concepts.

It wasn't until I started to teach the pilot section that I realized we'd been much too conservative.  We'd simply assumed that the goal was to teach students the standard 'classical genetics' concepts.  But what we should have done is first thought long and hard about what students should be learning in a modern 'fundamentals of genetics' course.  That is, what genetics facts and concepts will our students actually use, not just in later courses but in the rest of their lives?

Way back, the answer was that students needed to learn genetic analysis, for two reasons:  First, analysis of how phenotypes are inherited in crosses used to be the most powerful tool for understanding how organisms work.  Even if students weren't going to go on to do this analysis themselves, as biologists they needed to understand how it was done.  And following in the footsteps of the great geneticists was thought to be the best way to learn it.  Second, genetic analysis is hard, and learning to do it trains the mind in rigorous thinking.  Genetics students' experience at solving complex genetic problems was expected to make them better at solving all kinds of problems, in everyday life as well as academia.

Although genetics has changed dramatically, this motivation has largely been left unquestioned.  Although I didn't buy the 'following in the footsteps' part, I accepted the rest.  But the importance of classical genetic analysis to biology is shrinking day by day, displaced by powerful molecular methods.  Worse, improved understanding of students' learning suggests that most genetics students pass their exams using pattern-matching rather than the general problem-solving skills we thought they were developing.

So, what should today's biology students take away from a 'fundamentals of genetics' course?  What will they use in later courses?  What will they use in the rest of their lives?  Are there other concepts that every educated person know about?

So here's a partial list of learning objectives for a modern course in the fundamentals of genetics.  Yes, I know these aren't all phrased as actions students should be able to do, they aren't in a sensible order, the list is incomplete, and the syntax isn't even consistent.  PLEASE give me suggestions for improvement in the comments.
  • Students should be able to detect basic errors in news coverage of genetics stories.
  • Students should be able to understand why a genetic test or sequencing aids medical diagnosis and treatment.
  • They should understand how genetic differences affect health risks.
  • Which genetic principles apply to all organisms.
  • The extent to which the differences between individuals (humans and other species) are due to differences in their genes.
  • How the phenotypes of diploid organisms are affected by interactions between different versions of a single genes, and between different versions of different genes.
  • How offspring inherit genetic information from their parents (how meiosis and mating work).
  • How genes and genomes change over the generations and over evolutionary time.
  • At a simple level, how control of gene expression leads to differentiated phenotypes (a special case of gene interactions).
  • They should be able to think about ethical and societal issues arising from genetics.


Dave Bridges said...

its hard to do/interpret genetics without a strong understanding of probability. I would probably incorporate somehow before genetic analysis that to make sure that students can understand the basic statistics.

What about, more generally how genetic information is encoded and passed along (also some mention of genomics)

John Timmer said...

I think one thing that confuses many people is the difference between the phenomena of genetics - basically, how we see inheritance having an effect - and genetics as a tool, with things like genetic screens, breeding of double knockouts, epistasis, etc. They are very different things, and i don't think most students end up appreciating that.

jchoigt said...

I agree with Dave Bridges about stats. I would also add, along that vein, fundamentals of population and quantitative genetics, as well as linkage analysis. I think the revolution in DNA sequencing makes these skills MORE important, not less.

biopunk said...

I'll also urge the stats recommendation.

And a refresher on natural selection or evolutionary theory might help while discussing conserved sequences, etc.

Hopefully, avoiding the big picture getting lost in the minutiae...

Nicole said...

Thanks for this! I'm a new sessional instructor, just recently hired to teach "Genetics Analysis" (3rd year - lectures and labs), and I'm looking for ways to incorporate real-world perspectives and implications into the current course. I don't have full freedom to re-vamp the course (and don't necessarily think it needs a full overhaul), but your key take-home messages are really helpful. I'll also take the recommendations to drive home the stats fundamentals into consideration as I structure my lessons. Any additional comments/suggestions are hugely appreciated.

Rosie Redfield said...

I think the big issue isn't statistics but the absolute fundamentals of probability. Many students don't realize that each meiosis is an independent toss of the coin (or even that each toss of the coin is an independent toss of the coin). And given the probabilities of two independent events, they can't calculate the probability that neither will happen.

Mike the Mad Biologist said...

Another thing that should be covered (and perhaps it falls under the first point) is basic quantitative genetics (i.e., heritability). The human genetics work of the last decade is predicated on the idea of heritability, and students should understand what that is and what it actually measures.

Mika Sissonen said...

Hi Rosie - I found your blog via links from a story about your newsmaker award from Nature (congratulations!) after I recognized your name...I think I was in one of your classes at UBC in the mid '90s.

Your "what should we teach?" question caught my eye in particular - a year or so ago I read The Selfish Gene by Richard Dawkins, and it stunned me for two reasons: first, for its clear explanation of the importance of the "replicator" concept and how that turns the concept of human life on its head, and second, for the fact that this bigger-picture view of replicators driving life hadn't dawned on me through all the various genetics classes I took.

So my suggestion would be, in addition to all the stuff you teach about human genetics in particular, to also talk about - for perhaps at least a full one-hour class - the importance of the concept of replication in general, and how it's affected by the longevity, fecundity, and copying fidelity of whatever is being copied.

Rosie Redfield said...

@Mike, Dave and others,

Reading James Gleick's brilliant book The Information has shown me the centrality of concepts of information ad replication to genetics, and one of my very first lectures next term will try to frame the whole course in these terms.

(I'm now expanding this blog post into a short article for PLoS Biology's education section.)

Iddo Friedberg said...

The connection between sex, genetics & evolution. Cannot be stressed enough. (1) Sex is the primary contributor to genetic variation; (2) variation is the material upon which evolution is acting; and to complete the circle:(3) the evolution of sex as a diversity-generating mechanism (Red Queen or whathaveyou).

Francine Marques said...

I totally agree that basic genetic courses should be re-structured on the basis that there is too much free information available everywhere these days, and we should help students to develop critical thinking and evaluation of sources of information (if reliable or not), rather than be focussing on very specific contend. As teachers we should guide them on where to look for reliable information, and be critical even with journal articles, as there are several not reliable these days, such as highlighted recently by Dr John Bohannon ( In my opinion, courses should focus on basic genetics, in order to provide students with a basis for critical analysis, defining and introducing these terms, but also relating how they apply to their lives – this has been one of the points my students highlighted last semester, that they would like to relate the contend to their lives more than currently available in the course. I thought I was doing a good job giving them heaps of examples, but apparently not – they want more details on how that apply to them and perhaps their families and friends, so maybe focusing on monogenic traits present in the class and calculating genetic probability would be an example. Definitely they should be able to understand and discuss ethical issues arising from genetic discoveries. I think what we also need is more active learning as a way to make students actively participate and generate discussions. Another way is giving basic genetics in the classroom and then providing links to videos on YouTube and compulsory online discussion boards.