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Author Topic:   Life - an Unequivicol Definition
Member (Idle past 378 days)
Posts: 179
From: Scotland
Joined: 05-08-2006

Message 291 of 374 (774259)
12-15-2015 10:59 AM
Reply to: Message 267 by AlphaOmegakid
12-10-2015 9:50 AM

This paragraph states my claims clearly. But apparently you have a low reading comprehension or you ignore my argument completely. A virion outside a host cell is non-living by my definition. When a virus enters the cell, it is the cell that is alive, not the virus by my definition. The virus is a poison to the cell. The virus causes the cell to multiply the chemical poison. The cell explodes and the non-living chemical poison is released into the environment. At no time, and unequvically does my definition declare a virus alive.

But then where does the bacterium Chlamydia trachomatis fit into your definition? This is a obligate intracellular pathogen that cannot survive outside the host cell. This is due to the fact that it lacks the ability to synthesise nucleotides, which are required for not only the formation of ATP and NAD but also in order to replicate it’s own genome. These components required for metabolism and cell division it must extract from it’s host cell. Of course this bacterium eventually needs to infect other cells, so it forms elementary bodies which are metabolically inert, that will survive the external environment. These burst out of the host cell, killing it.
And just out of interest there are viruses, such as Hepatitis B and C, which produce virions without killing the host cell. It is actually the immune systems reaction to the virus presence that results in the host cells death.

Then we have Mimi virus, one of the largest viruses discovered, which has a genome of 1,181,404bp with 979 protein-coding genes. These include genes which were previously thought to be only encoded by cellular organisms. As a comparison, the Chlamydia trachomatis genome is 1,042,519bp long with 894 protein-coding genes.

I would like to know why you place so much significance on ATP? It is just a currency within the cell to transfer energy from exothermic reactions to endothermic reactions. Even the molecule itself is cobbled together from individual molecules common in the cell i.e. the adenosine (or guanosine in GTP) nucleotide base and phosphate backbone from DNA.

Final question is, if an organism is capable of completely taking over another organisms protein synthesis mechanisms, does it need to produce it’s own ATP?

This message is a reply to:
 Message 267 by AlphaOmegakid, posted 12-10-2015 9:50 AM AlphaOmegakid has not yet responded

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