Fall Callback 2020
Yesterday (12/1/2020), from 3:30-5:00pm, we had our Fall 2020 edition of our programs callback [for middle school students], this time held virtually and led by Professor Jamie Henzy and 4th year Health Science undergraduate student Teddi Stanley. 13 students came to learn about DNA and biology research at Northeastern.
The students started with some background on what DNA (Deoxyribonucleic acid) is, presented by Teddi (What is DNA?). Next, students did a DNA extraction experiment, using salt, water, dish soap, and rubbing alcohol to extract DNA from their saliva (and in Professor Henzy’s case: peaches). The alcohol effectively breaks down the cells and allows the DNA to come out – appearing as a gooey clear/whiteish slime/gel substance. Throughout the callback, Professor Henzy and Teddi explained more about what was going on in the experiment and answered questions about DNA and biology, with some of the interesting questions/answers below (with some additional info added by me):
Q: Is this what DNA actually looks like?
A: Sort of. The slime like substance is actually lots and lots of DNA strands, as DNA itself is incredibly small. To see individual DNA strands, you would need an incredibly strong microscope, a scanning electron microscope. These are large and expensive – often found in biology labs to conduct research on tiny things.
DNA Structure
DNA is made up of 4 bases, or letters: A (adenine), C (cytosine), T (thymine), and G (guanine). These letters pair up into base pairs as a double helix. There are a LOT of letters in the human genome, ~3.1 billion of them. These letters are stored in volumes of books (Chromosomes): humans normally have 23 pairs (46 total), but the number varies by organism (List of organisms by chromosome count). You can view the genome of various organisms using the NIH Genome Data Viewer, although it is quite technical.
Q: How do we examine DNA?
A: We use a process known as DNA sequencing: looking at the amount and determining the order of letters in the DNA. You might have heard of the Human Genome Project, which set out to sequence the entire human genome. This process took 13 years (starting in 1990), costing about $1 billion dollars. Technology has advanced rapidly and sequencing the genome of a human today takes about a day and costs less than $1000. Today you can have your own genome (or parts of it) sequenced by a variety of companies (23andMe, AncestryDNA, Nebula Genomics), although there are definitely privacy concerns related to this.
Q: What is the di
fference between DNA and RNA?
A: DNA can be seen as the instruction manual, but you can’t remove it from the library. RNA (ribonucleic acid) is similar, expect it’s a copy of a page from the library – it can be written on and disposed of as needed. More technical: RNA is made up of letters, using the same A, C, and G letters, however the T is replaced by a U (uracil), and unlike DNA, it is a single strand of DNA (although it folds back on itself, making it look similar to a double helix). The upcoming COVID-19 vaccines use mRNA (messenger RNA, a subtype of RNA) to teach our cells how to make a substance it can use to fight against the Coronavirus: learn more here.
Q: How much DNA do we share with our siblings?
A: We share about 50% of our DNA with our siblings. We also share about 50% of our genes (what is a gene?” with bananas. However, this is a misleading statistic (we don’t look more like bananas then our siblings), as genes make up just a small part of of our DNA, so effectively we share only about 1% of our DNA with bananas. We also share 96% of our genes with chimpanzees, 90% with cats, 85% with mice, and 61% with fruit flies.
Q: I heard a story awhile back about glow in the dark rabbits, can I make myself glow in the dark too?
A: The story is definitely true – as this was a research project in the early 2010s, although the ultimate goal of the project was actually to create a technique “that could one day lead to animals capable of producing medicines in their milk”, which would drive down the cost of drug manufacture. We can do these things by taking a sequence (a recipe), usually a snippet of RNA, from one organism and putting it into another organism. A particularly useful process used in biology research is to modify things in a specific way (such as making them glow) so that scientists can see the effects of their research better: these are called reporter genes.
You may have also heard about GMOs, or genetically modified organisms, which are organisms that have had their genetic material altered in some way. This term is often thrown around by the media and politicians, with arguments for and against their use. A film I strongly recommend watching related to this topic is Food Evolution, which shows both sides of the GMO argument and advocates data analysis and critical thinking.
There are definitely ethics (is something right or wrong) questions related to DNA modifications of animals, and particularly humans (such as by using CRISPR gene editing). Human germline engineering, i.e. editing the human genome in a way that it can be passed on to your children, is considered by the majority of the scientific community and general public a red line that should not be crossed.
Q: What else can we do with DNA/RNA:
A: Professor Henzy was recently a judge in an agar art (also called germ painting) contest – wherein contestants use genetically modified microbes as their paint and agar as their canvas. Check out the ASM 2020 Agar Art Contest (public voting is currently open)!
