Conclusion
It is clearly seen that the amount of time the organ
has been dead has a great impact among the DNA it produces. DNA is no longer
produced after death, mainly because cells die and cannot keep dividing
itselfs. Moreover, there is surprisingly a great amount of DNA extracted,
taking into consideration that the organs we used weighed approximately 100 to
125 grams. In week 1 we extracted about 25 grams, which is more or less 25% of
the whole mass of the organ. This reveals the big amount of DNA which is present
in each organ.
Logically, as time
goes on, cells start to decompose and destroy, as a consequence, DNA decomposes
with them. We know that DNA is saved in the nucleus in eukaryotic cells, but
after cell death, the decomposition begins at the nucleus, and, therefore, in
the strands of DNA.
There is a big
distinction between DNA produced after the organs being dead in weeks 2 and 3.
After this, the decrease of the amount of DNA starts to become lower and lower,
probably because there is a larger amount of bacteria which keep the organ
surrounded and not affected by climatological changes.
Also, there are
less bacteria in the organ in week 1 than in week 5 because they are much less
time exposed to the outside world. The bacteria do not just protect the organ
and eat it, but also they produce DNA, which can alter our experiment.
This experiment
could be used in the future for therapeutic cloning, for example, because with
strands of DNA we could create whole new organs which would be very useful to
other people. Furthermore, we could create new proteins and hormones
changing the order of nucleotides. This would use a different aminoacid than an
expected, so, a new protein.
Some materials
have a specific function, for example, parsley is necessary because it softens
the solution. Alcohol and dish washer are essential. The dish washer breaks
down the molecules of DNA, separating them from the rest of cells. The alcohol
being poured slowly down the sides makes a solution which is completely
heterogeneous, and, according to a principle in physics, the thing that has
more volume, in this case, DNA, will come out and try to mix with the lighter
part, the alcohol. This makes us have DNA which can easily be taken out of the
beaker now.
The video shows
the experiment done, and now it is corrected.
Evaluation
Weak points
- Possibly we did not
extract as much DNA as it was possible, mainly because as we stirred the
organ, we were supposed to only use the liquid part, the solid part we did
not have to use. Therefore, more DNA which could be found there could be
extracted.
- We stirred the testicles for a longer amount of time than estimated
because there was very little liquid and the quantity of DNA would be
clearly reduced.
- In some cases we poured more amount of a certain material than needed,
since we saw that perhaps some substances could still be found in the
beaker.
- It is possible that stirring the solution too hard may have affected
the molecules of DNA, and consequently, not have produced as much as it
should.
- The main weak point is
that we cannot know if the DNA came from the organ which we had or from
the bacteria which surrounded it. Due to the fact that DNA is universal
for all living beings, DNA from a bacteria is equal to DNA from an animal.
Therefore, the bacteria are a variable that we cannot control and that
have a very big impact on our experiment.
- We could not know when the animal had been killed, because the butcher
did not know, so the time we give is very relative.
Improvements
- We should have spent more
time trying to make all the substances pass through in order to have a
larger amount of liquid.
- We should have cut the organ several times so that it would be much
easier to stir, and avoid the breaking of the molecules.
- Putting the organ in water an hour before the experiment took place
was an improvement that we should have thought about earlier because it
would have saved us a lot of time.
- Making sure that putting the exact amount of liquid to not make any
mistakes is a good improvement because it will make our experiment
quicker, as there will be a less amount of things to clean.
- To improve the quantity of DNA, and also to reduce the chances of
possible errors, we could have mixed the mixture more gently. Furthermore,
the mixture has got to be completely homogeneous, which did not completely
be.
- Comparing our results after having done the complete research would be
helpful because we would make sure there were no silly mistakes which
could affect our complete experiment.
- To improve the quality of the experiment, before starting to stir the
organs, we could have cleaned them to reduce the amount of bacteria in the
organs, and therefore, more “pure” DNA.
- We could have put in a better way the DNA in the microscope because
some parts were thicker than others and it was hard to see through the
microscope.
Limitations
- One of the main problems
we had was that the mixer was broken by other students, so we spent two
weeks not being able of doing the experiment. However, we met at Pablo’s
house and did it there because his mother did not let him bring another
mixer to school.
- We have had less time in some lessons because we had to go and buy the
organs, which took a while. In the meantime, the other person prepared the
materials.
- The laboratory was, at times, very crowded and we could not do the
experiment correctly because there was not enough amount of space.
