Questions on "Random" Mutations

Taylor 31 wrote: Quite understandable - it can definitely be difficult to comprehend. I’ve seen a really nice movie of it, which you can see too on Carl Sagan’s Cosmos series, Episode #8 (which is on disk #5), titled "Travels in Space & Time", and goes from 48:50 to 54:25. Another (though not exactly identical) set of line art drawings for the flip-movie, also in Sagan’s Cosmos series, can be found on disk #2, episode #2, "One Voice in the Cosmic Fugue", between 25:44 and 32:10. You can buy the set on amazon, and It’s well worth it - a huge amount of science (and wonder to go along with it), packed into and intriguing and historic series.How it works is amazing, yet simple when you think about it. To make more “information”, to go from a bacteria on up, even to a whale, just duplicate, mutate, and repeat.First, understand the basic types of mutations:Here are some basic types of mutations and how they work:
Duplication of a stretch of DNA. This is like accidentally copying part of a book twice. Example - when making a copy of a book that has chapters 1, 2, 3,4,5,6,7,8,9,10,11, 12, you end up with a book that has chapters 1, 2, 3,4,5,6,7, 3,4,5,6,7, 8,9,10,11, 12
Deletion of a base pair. AATCTGTC becomes ATCTGTC
Addition of base pair AATCTGTC becomes ACATCTGTC
Transposition (like a mirror) AATCTGTC becomes CTGTCTAA
Change of a base pair (perhaps the most common, it’s what is usually talked about) AATCTGTC becomes AATGTGTC
All of these can have no effect, an effect which is selected for, or an affect which is selected against.To add information, first, take a functional gene, and make an extra copy using the duplication mutation. That won’t hurt the organism, since the second copy is simply redundant. Then use any of the other mutation methods so as to make the second copy do something new (such as make the bacteria tend to cluster with others). The organism still has the original copy doing whatever it is supposed to do, but now has the added ability of whatever the new gene does (such as digesting nylon, as in a species of bacteria).
The process can also add entire chromosomes in Eukaryotes.Thus, “additional information” is easy, and in fact inevitable. The process can grow up from a single DNA strand up to the 46 whole chromosomes of a human, containing literally billions of base pairs.Another good resource to start with is this basic book on evolution: http://www.amazon.com/Evolution-Triumph-Idea-Carl-Zimmerand the Sagan series: http://www.amazon.com/Cosmos-Carl-Sagan-DVD-SetHave a fun day--EquinoxEdited by Equinox, : typo (I said that humans have 4 whole chromosomes!) : DEdited by AdminAsgara, : geez I wish ppl would learn how to shorten long urls....

Taylor 31 wrote: Thanks! Mutations happen due to mutagens (chemical or physical things that cause mutation, see Mutagen - Wikipedia - also see the wiki page on mutation to see a diagram of the types of mutation I was describing, such as duplication, etc), ***and*** also just from simple copying errors when the DNA duplicates. There are indeed a lot of mutagens, including the cosmic rays from distant stars that have constantly streamed into earth throughout it’s history, and many common chemicals. Also, don’t forget the huge amount of copying that is done in the course of life - mistakes happen in copying, leading to a constant stream of mutations.Yep. Tremendous is a large amount, but the number of mutations over history is so big that we really don’t have a word for it. Nosy ned gave a good stab at this, but let me try a different angle. First, let’s just look at the time from 3 billion until 2 billion years ago. Nothing but bacteria on earth. Bacterial clumps were all over (many have been fossilized - they are called stromatolites). Bacteria are a few microns in size (let’s say about 10). So that means a 1 meter diameter clump has around 100,000^3 = 10 ^15 bacteria. You’ll need around 20 million to go around the earth in a single line (20,000 km/ 1 meter), so there could be at least millions of these on earth back then - let’s use 40 million as a conservative estimate. Now, bacteria copy and split at varying rates, which can be as fast as once every half hour. Let’s use just once every 12 hours as a very conservative estimate. So that’s 40 million of clumps * 10^15 per clump, copying twice a day, for a billion years (which is over 300 billion days) = around 10^33 copying events! That’s 1,000,000,000,000,000,000,000,000,000,000,000. Now each of those times the whole bacteria genome had to be copied - even if a mistake only happened in two or 5 locations each time, that’s still a tremendous number of mutations - and I only counted the time from 3 to 2 billion years ago, long before even a simple worm evolved.In humans, as has been already mentioned, there are estimated to be 10 to 100 mutations with every birth (!) - though I’ve heard estimates before of as low a s 2 or 3, and of course most of those are in junk DNA or otherwise have no effect. Yep. But remember that it takes many, many mutations to add up to, say a feather, or an eye, or an antelope. Think of the mutations to make a beak - one mutation makes the nose a tiny bit longer, the next a tiny bit longer, the next a tiny bit shorter (but that offspring dies for lack of food so we are back at the previous step), then the next makes the nose a tiny bit longer, and then a tiny bit harder, and on and on for hundreds of little steps. Selection constantly weeds out the mutations that don’t push things in the beneficial direction, and over millions of years (and millions of generations), we see huge changes, new features (made from old ones), and such. Could someone post an example of a new function arising, say breasts from sebaceious glands, flight from running, echolocation from calls, eyes from no0eyes or such? I’m out of time myself.Have a fun day!-Equinox