Hopwin wrote:
TheRiov wrote:
ok so using that logic, cells that do not have 46 total chromosomes are not human life?
Hopwin wrote:
TheRiov wrote:
using that logic Elmarieh, why are eggs not life?
Because they are haploid?Essentially the same reason viruses are not "life", they are DNA code snippets incapable of splitting or reproduction. Once they combine and become a complete cell, begin dividing and metabolizing adenosine triphosphate they are alive.
Clearer for you?
Actually that's not true Hopwin. Eggs, and sperm, are cells that metabolize ADP and divide via meiosis. The reason eggs and sperm aren't separate lifeforms is because they don't meet all the requirements of the biological definition of life. Those are homeostatis (the ability of an organism to regulate itself in an environment), organization (being composed of cell(s) and/or higher levels), metabolism (the ability to break down and create energy and chemicals through reactions), growth, adaptation, response to stimuli, and reproduction (at some stage of develop). Eggs and sperm aren't life because they fail to reproduce on their own, adapt on their own, and respond to stimuli without an organism controlling those functions.
The problem with that definition, though, is what about viruses? Viruses don't meet those criteria, therefore we don't consider them life. They respond a lot like life, though, except they can't reproduce without a host cell, nor do they show complex organization, metabolism, growth, or homeostatic functions. But they respond to stimuli and do adapt. They're an interesting case, but I do not believe they should be considered life.
But how does this apply to zygotes? Zygotes clearly show homeostatis in the womb by regulating heart rate and such. They can metabolize like any other organism. They do grow of course and the cells differentiate over time. They can adapt to situations, such as producing more or fewer proteins and enzymes. They respond to stimuli. This can be measured by how attentive fetuses and zygotes are when music is played for instance. They cannot reproduce, but at some point in their develop they will have that ability, so the definition is still applicable. The only point is that they cannot do it on their own. The mother must protect the zygote and help it with certain processes. But what about a sterile human that cannot reproduce? Aren't they still life? Therefore, the definition cannot be applied to an individual case. It needs to be applied to a grouping. Thus, I believe we're still in a gray area for zygotes. This is why I believe we should err on the side of caution. It's nearly impossible to say when it is life and not life, so playing it safe is the best option in my mind.