| From: spud(adonai) ® | 19/01/2001
11:50:47 |
| Subject: DNA and Genetics |
post id:
210381 |
| Do identical twins have the same
dna? A friend of mine thinks they do, but i said they don't as their fingerprints are different, thus there would have to be small differences between the two on the genetic level (besides the fingerprints). | |
| From: Drues ® | 19/01/2001
11:52:52 |
| Subject: re: DNA and Genetics |
post id:
210382 |
| Yes. Same DNA. But if you want to be a train-spotter about it, their DNA becomes more dissimilar as they get older because of random mutations, etc. | |
| From: J.F. ® | 19/01/2001
12:54:44 |
| Subject: re: DNA and Genetics |
post id:
210419 |
| I believe there is an element of
randomness, as well as some genetic determinism, in the fine details of
our body morphology. I have not studied fingerprints, but I used to do a lot of venepuncture on staff + patients many years ago. There was amazing variability in the precise location of veins between people, even between R + L arms in the same person, which may be assumed to be genetically identical. Look at your own forearms, wrists + back of your 2 hands to see what I mean. I would expect that randomness is involved in the fine detail of fingerprints, too. Compare the fingerprints on R + L index + other fingers, thumbs + toes, + you will surely see what I mean. I believe that there is some heritability of the frequency/ tendency to have types of patterns, ie whorls, loops + whatever else, though. | |
| From: Ordinary Person ® | 19/01/2001
13:02:57 |
| Subject: re: DNA and Genetics |
post id:
210426 |
| It has been suggested that
fingerprints are "epigenetic"; they are imprinted by random effects in the
womb. They are not brought about by DNA. Identical twins' DNA really is identical to start with. There is always the possibility of mutations throughout life, but this will not generally be the cause of the visible differences between identical twins; the fingerprints, birthmarks, slight difference in stature etc are non-genetic. | |
| From: Carmel ® | 19/01/2001
13:09:15 |
| Subject: re: DNA and Genetics |
post id:
210429 |
| There is always
the possibility of mutations throughout life Actually, more like a certainty, but it won't cause you to suddenly sprout a second or third head. These small mutations that occur throughout life include sunlight induced mutations as well as other carcinogens like cigarettes... Most mutations develop into cancers. Some, can lead other diseases however (although, like some cancers tend to have a genetic pre-disposition). Oh, OP, you have mail. | |
| From: lentil | 19/01/2001
15:15:01 |
| Subject: re: DNA and Genetics |
post id:
210515 |
| "Do identical twins have
identical fingerprints ? Even monozygotic twins (identical twins from the same egg) have slightly different fingerprints. Fingerprints form before birth and their shape is generally believed to be influenced by nutrition and the growth of fingers during the 13th week of pregnancy. Although they do follow patterns they are thought to grow in a more chaotic manner rather than on any basis of genetics. Even blood pressure is thought to play a role. As the fingers form, pads of skin develop on the ends of the fingers which eventually develop ridges. Foetuses with higher blood pressure will have swollen finger pads so the patterns formed are more likely to be whorls. Although fingers will become scared or blemished during life, the patterns themselves in forensic terms remain unaltered. Finger prints are always unique, not only to the individual but to the digit as well. While certain correlation of patterns often exists in the prints of twins, there the likeness ends." | |
| From: boxhead ® | 20/01/2001
3:17:36 |
| Subject: re: DNA and Genetics |
post id:
211119 |
| Most mutations
develop into cancers. Some, can lead other diseases however (although,
like some cancers tend to have a genetic pre-disposition). If we eradicate cancer will we stop evolving? Hi Carmel, Your statement got me thinking, (tic) we shouldn't wear sunscreen or stop smoking if we want the human race to evolve as quick as possible.(/tic) Seriously though, is cancer a side effect of the random mutations that drive evolution? boxhead® | |
| From: Dr. Ed G (Avatar) | 20/01/2001
3:41:27 |
| Subject: re: DNA and Genetics |
post id:
211123 |
| Yes, cancer is unequivocally the
downside of our ability to evolve. Without mutation there's no cancer, but
also there's no variation and consequently no evolution... and anything
that doesn't evolve to adapt to a (inevitably) changing environment become
extinct. However, mutation is only useful from an evolutionary perspective if it affects the germ cells (sperm and ova). So increasing mutation by cigarette smoking or other carcinogens or mutagens which do not effect these cells (except as a result of metastasis in which a primary cancer cell becomes a different type of cancer) serves only to kill the individual with no direct upsides for the species (apart from decreasing the surplus population... to quote Dickens). Soupie twist, Ed G. 
| |
| From: J.F. ® | 20/01/2001
10:51:34 |
| Subject: re: DNA and Genetics |
post id:
211160 |
| "Seriously though, is cancer a
side effect of the random mutations that drive evolution?" Carmel may be busy, so I will answer this now. When people use the word "mutation" without any qualifier, it is generally assumed to be referring to mutations in "GERM cells" (ova, sperm) that provide the DNA for the next generation of offspring. In cancer, however, there are "SOMATIC cells" mutating. These are body cells = lung, skin, and other cells which do not form offspring. Somatic mutations may accumulate in a long - lived somatic cell, until it becomes cancerous. It may then be destroyed by the immune syatem, or be programmed to die, which is ideal. I think it is now widely accepted that the transformation to become a cancer cell requires more than one change in the cell---- it requires multiple "hits" People (like me) in whom all their somatic cells lack one of the 2 copies of a vital cancer- suppressing gene, are at increased risk of certain cancers; one of the "hits" has, in effect, already happened. Examples OTTOMH include Wilm's tumour of the kidney, familial/ multiple Retinoblastoma, Gorlin's syndrome (mine; it is also called BCNS), and probably some of the breast + bowel cancers that seem to run in families. If anything "drives" evolution, I would say that it is selective pressure. Most mutations are deleterious, but a very very few provide necessary + valuable genetic diversity, that selection can work on | |