life

[jimmer]

is it possible to create life in a laboratory?

[j2buttonsw]

I guess it depends on how you define "life". In 1953, a young chemist named Stanley Miller carried out a historic experiment at the University of Chicago. He attempted to recreate the conditions during the Earth's early days by sparking electricity through a mixture of water and gases sealed in a flask. When Miller analysed the results, he was pleased to find traces of amino acids, the building blocks of proteins. Today, molecular biologists have been making strides with a top-down approach, breaking apart the innards of bacteria and viruses, and reassembling the components. Just last month, Craig Venter, famous for his pioneering work on the human genome project, announced his intention to create a brand new life form. Venter plans to strip down and reconstruct the genome of Mycoplasma genitalium, a primitive microbe that inhabits the genital tract. However, this isn't making life so much as rearranging it. In other words, they use the products of living organisms to re-make living organisms. They remain a long way from being able to put together a living cell from scratch.

[jimmer]

thanks. so this guy miller created ammino acids in a laboratory. does this have to mix with carbon to make life? thanks jim

[j2buttonsw]

Amino acids are the building blocks of proteins and contain carbon (along with nitrogen, hydrogen, oxygen and occasionally sulphur). Proteins are responsible for the control of the thousands of chemical reactions called life. The sequence of amino acids in a given protein is determined by DNA. A living cell is best thought of as a supercomputer - an information processing and replicating system of astonishing complexity. DNA is not a special life-giving molecule, but a genetic databank that transmits its information using a mathematical code. Most of the workings of the cell are best described, not in terms of material stuff - hardware - but as information, or software. Trying to make life by mixing chemicals in a test tube is like soldering switches and wires in an attempt to produce Windows 98. It won't work because it addresses the problem at the wrong conceptual level.

[jimmer]

ok thanks. so are you saying that it is not possible to create life in a laboratory without creating this DNA cell first? how is DNA created

[j2buttonsw]

DNA are polmers (like proteins) and are made up of 4 bases (guanine, thymine, cytosine and adenine) linked by a sugar-phosphate backbone. The order of the 4 bases ultimately determines what the amino acid sequence will be. The idea of DNA is that it is a replicatable blueprint of the cell's contents since to be called living, you must be able to do two things: reproduce and metabolise. One can sythesise from scratch DNA of a give sequence (by so-called gene machines) but it is very complex and difficult to achieve. Rather than creating DNA de novo, scientists generally cut and paste known DNA sequences to form "new" genes. But, as has been said, you can't dump loads of genes into a test-tube and expect life: it is far more complicated than that.

[jimmer]

i get your point. but i was lead to believe that on upcoming misions to europa and mars we are likely to find some new life forms because life would finda way to exist in all types of conditions. is there a gap in scientific knowledge that needs to be filled before we can create life or do you believe that given the right ingredients nature will sort the puzzle out for us? jim

[incitatus]

Is a virus alive? Recently molecular bilogists recreated the genetic sequence of polio in the lab. If you stuck this into a cell it would make the polio virus, which could then reproduce in the normal way.

[jimmer]

i don't know but it's a bloody good question. is a virus alive?

[j2buttonsw]

A virus can certainly reproduce but whether it can "metabolise" independent of its host is up for debate. To get off the DNA/RNA based organisms, can you describe prions as living?

[anthomson]

I seem to remember reading in a Stephen Hawkings book that it is quite possible that Earth is the only place in the universe where life may have started. Considering how complex cell reproduction is I can well believe it. Quite a sobering thought.

[incitatus]

j2- another good question. a bit sobering if not, though. its like having a major disease crisis caused by rampaging eggwhite. ant-hawking was just guessing and he knew it. noone knows what the statistics on life formation are like. they may be bad or good. for all we know every star has slime growing round it.