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Author Topic:   Evolution is True Because Life Needs It
Percy
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Posts: 22359
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


Message 175 of 188 (671505)
08-26-2012 6:30 PM
Reply to: Message 174 by barnes
08-26-2012 6:04 PM


Re: Silly creationist story
Hi Barnes,
Cancer is a disease that causes cells to grow uncontrollably. Checking out the Wikipedia entry, the causes can be genetic, but there are many other causes.
A genetic change (mutation) can cause cancer, but usually not. Cellular reproduction almost always includes at least a few mutations, and the vast majority of cells are not cancerous. Every fish, reptile and mammal began as a single cell that split many, many times to become billions of cells. Almost every cell division resulted in a at least a few mutations, yet cancer is rare.
A cell's internal machinery does possess mechanisms protecting itself from genetic accidents, but mutations slip through nonetheless.
barnes writes:
Adaptation precludes no physical change but improvements relative to the environment.
Adaptational change below the species level most definitely includes physical changes. For example, the finches of the Galapagos that have been studied so extensively change the size and shape of their beaks in response to environmental factors.
If you want to see how to produce quotes then click the "peek" button for this message to see an example.
--Percy

This message is a reply to:
 Message 174 by barnes, posted 08-26-2012 6:04 PM barnes has not replied

Replies to this message:
 Message 177 by foreveryoung, posted 08-26-2012 8:42 PM Percy has replied

  
Percy
Member
Posts: 22359
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


Message 178 of 188 (671522)
08-26-2012 9:30 PM
Reply to: Message 177 by foreveryoung
08-26-2012 8:42 PM


Re: Silly creationist story

This message is a reply to:
 Message 177 by foreveryoung, posted 08-26-2012 8:42 PM foreveryoung has replied

Replies to this message:
 Message 179 by foreveryoung, posted 08-26-2012 9:59 PM Percy has replied

  
Percy
Member
Posts: 22359
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


Message 180 of 188 (671526)
08-26-2012 10:17 PM
Reply to: Message 179 by foreveryoung
08-26-2012 9:59 PM


Re: Silly creationist story
Hi ForEverYoung,
You forgot the quote codes.
foreveryoung writes:
There is nothing in that article which supports your claim that mutations occur roughly everytime a cell divides.
Sure there is:
Wikipedia article on mutation rates writes:
Using data available from whole genome sequencing, the human genome mutation rate is similarly estimated to be ~1.110-8 per site per generation.
The human genome has about 3.2 billion sites (base pairs), so doing the multiplication we find that the number of mutations that can be expected in every newborn is about 35. The odds of a newborn with no mutations is (1 - 1.110-8)3.2109, which is about 510-16 or less than one in every quadrillion births.
--Percy

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 Message 179 by foreveryoung, posted 08-26-2012 9:59 PM foreveryoung has replied

Replies to this message:
 Message 181 by foreveryoung, posted 08-26-2012 10:46 PM Percy has replied
 Message 184 by Dr Adequate, posted 08-26-2012 11:48 PM Percy has seen this message but not replied

  
Percy
Member
Posts: 22359
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


(1)
Message 182 of 188 (671530)
08-26-2012 11:26 PM
Reply to: Message 181 by foreveryoung
08-26-2012 10:46 PM


Re: Silly creationist story
Hi ForEverYoung,
Cell division is not a perfect process. It requires copying the DNA, and occasional copying errors are nearly inevitable. The production of both gamete and somatic cells will almost always include mutations. Here's the full paragraph describing specific mutation rates from that webpage at Wikipedia:
Wikipedia on Mutation Rates writes:
In general, the mutation rate in unicellular eukaryotes and bacteria is roughly 0.003 mutations per genome per generation. The highest per base pair per generation mutation rates are found in viruses, which can have either RNA or DNA genomes. DNA viruses have mutation rates between 10−6 to 10−8 mutations per base per generation, and RNA viruses have mutation rates between 10−3 to 10−5 per base per generation. Human mitochondrial DNA has been estimated to have mutation rates of ~3 or ~2.710−5 per base per 20 year generation (depending on the method of estimation); these rates are considered to be significantly higher than rates of human genomic mutation at ~2.510−8 per base per generation. Using data available from whole genome sequencing, the human genome mutation rate is similarly estimated to be ~1.110−8 per site per generation.
It doesn't matter whether it's viruses or prokaryotes or eukaryotes or gametes, there will almost always be mutations because the mutation rate is non-zero and the number of base pairs is at least in the millions and often in the billions. The includes the production of eukaryotic cells during fetal development and subsequent growth during life for human beings.
--Percy

This message is a reply to:
 Message 181 by foreveryoung, posted 08-26-2012 10:46 PM foreveryoung has replied

Replies to this message:
 Message 183 by foreveryoung, posted 08-26-2012 11:37 PM Percy has replied

  
Percy
Member
Posts: 22359
From: New Hampshire
Joined: 12-23-2000
Member Rating: 4.7


Message 186 of 188 (671536)
08-27-2012 12:18 AM
Reply to: Message 183 by foreveryoung
08-26-2012 11:37 PM


Re: Silly creationist story
foreveryoung writes:
When you multiply the size of the human genome by the mutation rate per site per generation you get 35 mutations per genome per generation. How many cell divisions occur in one spot in the human body in a 20 year generation? If it is significantly greater than 35 than you don't have a mutation roughly occurring everytime a cell divides. For example if one spot in the body has cell division occurring 3500 times in a 20 year period, you have mutations occurring one time in every 100 cell divisions.
Dr Adequate mentioned some important clarifications. My example was not for somatic cells but for gametes and the process of human reproduction. I used that example because Wikipedia provided figures for that and not for somatic cells, but the principles are the same. The copying of genetic material, whether free DNA, nuclear DNA, mitochondrial DNA, or RNA, is not perfect. Occasional errors creep in, and in the vast majority of circumstances they do not cause cancer.
--Percy

This message is a reply to:
 Message 183 by foreveryoung, posted 08-26-2012 11:37 PM foreveryoung has not replied

  
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