DNA STUD or DNA DUD: See how you rate!

seqWell recently posted a series of 6 questions to help scientists test whether they are a DNA STUD or DNA DUD when it comes to their knowledge of DNA.   Check out the questions and answers below!

Question 1: Nucleic acids were discovered by a single man? (T/F) – True

You may believe that James Watson and Francis Crick, aided by Rosalind Franklin’s research, discovered DNA in the 1950s, but in fact, they discovered the double helix structure of DNA. It was Friedrich Miescher who first identified nucleic acids in 1869 and dubbed them “nuclein”. This name was later changed to “nucleic acid” and eventually to “deoxyribonucleic acid,” or DNA.  Many other scientists produced foundational knowledge between 1869 and the 1950s that Watson and Crick harnessed for the groundbreaking discovery of DNA’s helical structure. Read more…

Source: https://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397/

Question 2: What is the approximate percentage of DNA that humans share with bananas?

Answer 1: 25%
Answer 2: 60%
Answer 3: 75%
Answer 4: 90%

There is truth to the amazing statistic that we share 60% of our DNA with bananas, but we’ll admit a range of numbers have been reported. Here’s where we got our answer. It originated from a 2013 National Human Genome Research Institute (NHGRI) program led by Dr. Lawrence Brody.  A quote from Dr Brody about the study:  “…they took all of the banana genes and compared them one at a time to human genes. From that, they culled a degree of similarity (if the banana had the gene but the human didn’t, that didn’t get counted). About 60 percent of our genes have a recognizable counterpart in the banana genome! Of those 60 percent, the proteins encoded by them are roughly 40 percent identical when we compare the amino acid sequence of the human protein to its equivalent in the banana”.

Sources: https://science.howstuffworks.com/life/genetic/people-bananas-share-dna.htm, https://www.pfizer.com/news/articles/how_genetically_related_are_we_to_bananas

Question 3:  Many types of selfish DNA have been discovered. Which of these is NOT a selfish genetic element?

Answer 1: Transposable elements
Answer 2: B chromosome
Answer 3: Killer plasmids
Answer 4: Segregation-enhancing elements

Selfish genetic elements (SGEs) – also referred to as selfish genes, selfish DNA, or parasitic DNA – are genetic segments that can increase the rate of their own transmission, even if they have no positive effect on fitness. The observation of SGEs was made almost a century ago, but it wasn’t until two papers were published back-to-back in Nature (1, 2) in 1980 that SGEs gained widespread exposure. Since then, there has been an explosion in SGE research, with a diverse range of SGEs reported and found in most groups of organisms. These include (among other examples) transposable elements, B chromosomes, and Killer plasmids. Originally thought to be genetic oddities without relevance, they are now recognized to affect a large number of biological processes.

Sources: https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007700, https://www.pnas.org/doi/10.1073/pnas.1102343108

Question 4: Which fact about Octopus DNA is INCORRECT?   Octopi…

Answer 1: Have proteins humans don’t
Answer 2: Can edit their own DNA
Answer 3: Lack mitochondrial DNA
Answer 4: Have many transposons

It was a trick question as there were actually two facts that were incorrect, but that gave everyone a 50% chance of answering correctly!

To quote a 2015 NIH article entitled Untangling the Octopus Genome: “The octopus seems almost like an alien species…It can climb walls and open jars. And its nervous system contains nearly half a billion neurons, more than 6 times the number in a mouse brain.” In 2015, scientists sequenced, analyzed, and published in Nature their findings regarding the genome of the California two-spot octopus. In this article, the authors estimated that the octopus genome contains over 33,000 protein-encoding genes while the human genome contains approximately 20,500 protein-encoding genes. Another notable fact in the publication – nearly 50% of the octopi’s genome is composed of transposable elements!

What about the two incorrect facts? There are no reports that octopi lack mitochondrial DNA. Now the tricky answer. A study reported in Cell demonstrates that Octopi can edit their RNA, but not their DNA.

Sources: https://www.nih.gov/news-events/nih-research-matters/untangling-octopus-genome, https://www.cell.com/cell/fulltext/S0092-8674(17)30344-6

Question 5: The vast majority of human DNA is…?

Answer 1: Right-handed
Answer 2: Left-handed

While Watson and Crick reported the structure of “right-handed DNA” in 1953 (referred to as the B form, or B-DNA), two other forms A-DNA and Z-DNA do exist. Right-handed B-DNA, however, is by far the most common.

Source: https://www.nature.com/scitable/topicpage/discovery-of-dna-structure-and-function-watson-397/

Question 6: How much money did it cost to generate the first human genome sequence as part of the Human Genome Project (HGP)?

Answer 1: $500 million – $1 billion
Answer 2: $1.1 billion – $5 billion
Answer 3: $5.1 billion – $15 billion
Answer 4: > $15 million

Estimates of this monumental step in sequencing the first human genome can vary. Our question and answer were taken directly from NHGRI’s The Cost of Sequencing a Human Genome.

“Once significant human genome sequencing began for the human genome project (HGP), a ‘draft’ human genome sequence was produced over a 15-month period (from April 1999 to June 2000). The estimated cost for generating that initial ‘draft’ human genome sequence is ~$300 million worldwide, of which NIH provided roughly 50-60%.

The HGP then proceeded to refine the ‘draft’ and produce a ‘finished’ human genome sequence (as described above), which was achieved by 2003. The estimated cost for advancing the ‘draft’ human genome sequence to the ‘finished’ sequence is ~$150 million worldwide. Of note, generating the final human genome sequence by the HGP also relied on the sequences of small targeted regions of the human genome that were generated before the HGP’s main production-sequencing phase; it is impossible to estimate the costs associated with these various other genome-sequencing efforts, but they likely total in the tens of millions of dollars.”

The above explanation illustrates the difficulty in coming up with a single, accurate number for the cost of generating that first human genome sequence as part of the HGP.  Such a calculation requires a clear delineation about what does and does not get ‘counted’ in the estimate; further, most of the cost estimates for individual components can only be given as ranges. At the lower bound, it would seem that this cost figure is at least $500 million; at the upper bound, this cost figure could be as high as $1 billion. The truth is likely somewhere in between.

The above estimated cost for generating the first human genome sequence by the HGP should not be confused with the total cost of the HGP. The originally projected cost for the U.S.’s contribution to the HGP was $3 billion. In actuality, the Project ended up taking less time (~13 years rather than ~15 years) and requiring less funding – ~$2.7 billion. But the latter number represents the total U.S. funding for a wide range of scientific activities under the HGP’s umbrella beyond human genome sequencing, including technology development, physical and genetic mapping, model organism genome mapping and sequencing, bioethics research, and program management.”

Source: https://www.genome.gov/about-genomics/fact-sheets/Sequencing-Human-Genome-cost