Download The Nature of Things: The Immortal Thread

The Secret of Life: The Immortal Thread
1. What are the four letters in the DNA “alphabet”? What do these letters stand for?
2.
A = Adenine
3.
Show which letters of the “alphabet” are always paired together.
A bonds with T
T =Thymine
C =Cytosine
G = Guanine
C bonds with G
4. Explain why Dr. Karl Stetter is so interested in the bacteria that grow in hot springs?
Stetter’s interest in these bacteria is that they
can survive at all at such extreme temperatures
and in environments that would be toxic to
most living things. Furthermore, the fact that
the DNA is not destroyed and bacteria
reproduce asexually (and therefore change little
over time), provides a glimpse into what early
life forms on earth were like.
4. Why did Dr. Craig Venter choose brain tissue as his part of the human genome study?
Venter chose brain tissue to start searching for human
genes because as much as one third of human genes go
into making the brain.
FYI: Venter recently created a synthetic life form. He
removed DNA from a living bacteria and replaced it with a genome
that he created in the lab. This is like wiping a hard drive on a
computer clean and then replacing it with software of your own
choosing!
How does creating “synthetic life” make you feel? Why?
5. Why did Dr. John Sulston choose the roundworm species known as Caenorhabditis elegans to do his research?
Sulston chose this species because :
1. It has specialized cells and organs similar to
more complex organisms (such as ourselves).
2. The adult form consists of approximately 1,000
cells. This makes the study of individual cells and
the changes they go through, from embryo to adult
possible. What has been learned about this organism can act as a
model for how more advanced organisms develop.
6. How can we apply Sulston’s findings to what we know about the human organism?
By studying what goes wrong in the development from cell to tissue to
organ, we may apply that knowledge to similar pathways of
development in humans. In other words, Sulston’s methods can act
as a model for how to study more advanced organisms.
7. Briefly explain the procedure Dr. Paul Nurse performed on brewers yeast.
He took healthy yeast cells that could divide normally
and deliberately “broke” the way they work by
mutating the gene responsible for telling the cell when
to divide. He then added a “genetic soup” of human
genes to a solution containing the mutated yeast cells.
Some of the yeast cells incorporated a human gene into
their own DNA and were able to fix themselves,
dividing normally.
8. What is so astounding about Nurse’s results?
Nurse’s results showed that certain genes, important ones like those
that control cell division are conserved throughout time and from
species to species. He won a Nobel Prize for later finding a human
gene that performed the same function as that in the yeast cell. His
work further confirms the fact that all life shares a common
foundation.
9. David Suzuki, the narrator of the film, is a biologist and specializes in working with DNA. How did his personal
story illustrate the possible dangers and misuse of our understanding of DNA? Provide other examples showing
the pros and cons of this type of research.
Suzuki begins the program with a story of how his
parents (which were Japanese but Canadian
citizens) were placed in internment camps during
the WWII. Because of their ethnicity, they were
thought to be a threat. The rest of the program
goes on to give many example how DNA is what
links all life together and unites us. We must be
careful that real knowledge of how DNA works
does not lead to even more ignorance and
prejudice than we already have.