Moalem discusses throughout chapter 1 about how some
diseases were actually helpful in the past.
For example, on page 21, even though cystic fibrosis is a deadly disease
today, people with cystic fibrosis were more protected from tuberculosis than people
without cystic fibrosis between 1600 and 1900.
This relates to the big idea 1, because the existence of these harmful
diseases today create variations which explains speciation and extinction. People with cystic fibrosis exist today,
because without people with cystic fibrosis, much more people would have died. Without any medical knowledge or genetic
variations, if all people were without cystic fibrosis, tuberculosis could have
led to an extinction. Thus, some
mutations proved to be helpful in some time or environment enabling people with
cystic fibrosis to be more likely to survive than people without cystic
fibrosis. This also explains why the
percentage of hemochromatosis carriers increased since 1347 and 1350 when the
number of death from the plague was at the highest according to page 15. Even though hemochromatosis is a deadly
disease today, hemochromatosis was a helpful mutation in the past that
ultimately made people with hemochromatosis to be more likely to survive and
pass on their traits, creating directional mode of selection. Back when the plague was prevalent, creating a different, unsanitary environment than today, natural
selection favored people with hemochromatosis enabling the population with
hemochromatosis to increase. How does this explain how more single-celled
life forms that could survive in harsh environment evolved into complex animals
today? What kinds of common mutations or differences
are seen between complex organisms and simple organisms? Looking at these differences, what environment
factors and/or changes could have made being a more complex organism more favorable
in survival?
(Woosik Choi: wchoi3@students.d125.org)
Well, this explains that more single-celled life forms could survive in a harsh environment today because they have become accustomed to the human body. A living pathogen or bacteria that has penetrated a humans defense system would become more accustomed to living in conditions that complex animals live in today. Some mutations could have arisen here solely due to natural factors. It is easier for a single cell organism to be mutated because it has less DNA and RNA therefore a higher percentage of mutations or more severe mutations would occur compared to a multi-cellular organism. This directly relates to the study of genetics and inheritance because it discusses how diseases can be caused by mutations, but it also connects to the current lessons, of antibodes and prevention of disease. This connects to Big Idea 1 because the disease evolve along with the multi-cellular organisms, all organisms go through an evolutionary proccess, as Dr. Moalem states on page 15.
ReplyDeleteAndrew Komarov
akomaro4@students.d125.org
Well, this explains that more single-celled life forms could survive in a harsh environment today because they have become accustomed to the human body. A living pathogen or bacteria that has penetrated a humans defense system would become more accustomed to living in conditions that complex animals live in today. Some mutations could have arisen here solely due to natural factors. It is easier for a single cell organism to be mutated because it has less DNA and RNA therefore a higher percentage of mutations or more severe mutations would occur compared to a multi-cellular organism. This directly relates to the study of genetics and inheritance because it discusses how diseases can be caused by mutations, but it also connects to the current lessons, of antibodes and prevention of disease. This connects to Big Idea 1 because the disease evolve along with the multi-cellular organisms, all organisms go through an evolutionary proccess, as Dr. Moalem states on page 15.
ReplyDeleteThe environment obviously plays a large role in chanigng a person's DNA, because there are very many mutagens in nature. Although this may not apply to humans, but for an animal, "an animal's environment constantly presents challenges-such as finding food, avoiding predators, and recovering from diseases." (Science Reference Center) Mutations in current times usually arise later in life, but mutations may occur at a young age, and only present themselves later in life. "Since most new mutations are harmful and since mutations with effects late in life tend not to be weeded out, late-acting harmful mutations can accumulate over time. They are virtually immune to elimination by natural selection, which may be why certain diseases, like cancer, occur predominantly in old age." (science reference center)
Of course it is different with animals and single-celled organisms like bacteria, because one simple mutation may not harm a multi-cellular organism because it is built with more antibodies, because of all the different pathogens that it has interacted with previously. Also, one mutation will not certaintly harm a multi-cellular organism because it has many other cells that may not be harmed. A single-celled organism on the other hand may be destroyed by a mutation because it only has to attack one single cell to kill the organism.
To evolve, it is more favorable to be a multi-cellular organism, because you have a higher chance of surviving over time, but your reproduction rate is lower than a single-celled organism. It is important to know that all of the antibodies that a multi-cellular organism builds up over time will save it's life in the long term, because it will have more resistance to deadly disease.
Andrew Komarov
akomaro4@students.d125.org
Outside Source:
Natural History; Feb92, Vol. 101 Issue 2, Special section p24, 19p, 8 Color Photographs