Science facts that amaze you?

fryup

exploding dust, amazing that such a common thing as dust can be so deadly in certain circumstances

https://www.youtube.com/watch?v=_bp9hGxPRlc

it tragically happened in england today

steddyeddy

The_Captain wrote: »

It's one of those things where there's no proof of it, but by induction and a knowledge of how evolution and hereditary genetics works, it's pretty much accepted that RNA came first.

It's unlikely that an incredibly complex double stranded nucleotide chain developed first and simplere single stranded RNA came later.
RNA contains genetic material, but it can also catalyse proteins, so it could have existed independently of DNA, replicating itself constantly and mutating itself rapidly due to the weakness/fragility of its bonds, with new strands and mutations developing all the time because of the amount of breaking down and rebuilding going on.

Although it gets quite hypothetical, it's assumed that RNA chains acted as a form of proto-life, with the same ecological drivers we have. They would have competed with other RNA strands to grow and replicate themselves, becoming more and more complex as time went on.

RNA chains would then (randomly) synthesise proteins that would improve their fitness compared to other RNA strands, and it's thought that these ribozymes eventually developed into DNA.

(Alternatively, RNA may have developed into DNA before forming the first cells/proto-cells. There's arguments to support it and no one is quite sure how RNA 'upgraded' itself into DNA within the constraints of natural evolution.)

Well the fact that's something's accepted by a lot of scientists isn't indicative of it's likelihood. The evidence does that.

Saying that the RNA world hypothesis is the best we currently have. Now saying that I have to take you up on your point that RNA is the simpler molecule. You said yourself it catalyses reactions unlike DNA, it contains an extra oxygen although it doesn't readily form double strands with other RNA molecules it can form a RNA-DNA hybrid with DNA.

It contains one extra oxygen than DNA and contains the base uracil which isn't found in DNA. What amazes me is in order to convert RNA into DNA i.e through the removal of one oxygen atom you need an enzyme called ribonucleotide reductase. This catalyses an incredibly complex set of reactions to remove one oxygen atom. So in order for there to have been DNA there must have been this enzyme.

Saying that the early environment might have been conducive to different oxidation states making the removal of an oxygen possible without the use of an enzyme.

There's quite a long tangent here if people are interested in the theory behind science. All science is based on a combination of deductive and inductive reasoning.
If you place your hand on a hot hob and burn it, deduction is working out that the hob burned your hand, while induction is working out that you will burn your hand if you touch hot oven hobs.

Induction essentially is using past experiences, or known outcomes, to make predictions about the future (although with RNA/DNA here we're using present day observances to make predictions about events billions of years in the past, but I'm sure you get what I mean).
We know the hob is hot, you know people have burned their hands on ovens in the past, but we're assuming we'll burn our hand if we put it on that hob based on past experience.

Bertrand Russell wrote about the problem of induction and how our faith in science may be misplaced.
He took a chicken as an example. The chicken is on a farm, with walls around it to keep predators out, the farmer feeds it, houses it, keeps it free from environmental hazards and anything that might cause that chicken harm. This little chicken scientist here might come up with a hypothesis "the farmer is a benevolent protector" and would test it. She'll try to put himself in harms way, but the farmer will keep her safe. She could intentionally break her own wing, but the farmer with fix him up. She could try to let predators in, and the farmer will shoot them before they can hurt the chicken.
Logically, the farmer is a great guy, doing everything he can to improve that chickens life. The chicken scientist could run trial after trial until he develops The Theory of Man: "Farmers protect chickens". All the observable evidence supports it, and it could go on like that for a year, with the chicken becoming more and more definite in it's beliefs as time goes on, it's had 365 days of evidence supporting its view and there's never been a shred of evidence that the farmer intends any harm towards that chicken.
On the 366th day, the farmer wrings it's neck and cooks it.

We may be in no better a position than the chicken which unexpectedly has its neck wrung.

With regards to abiogenesis, we're basing our hypotheses on the behaviour of present day RNA and DNA, and extrapolating that behaviour into what we think are the most likely conditions of Earth 4 billion years ago. There's a chance that there may have been an RNA precursor. RNA only exists today because it still has uses and advantages over DNA. If it didn't, it would have been completely replaced by DNA and we'd never know RNA existed.
There could have been all manner of proteins, pre-proteins and simple nucleic compounds in the early days of life but if they don't exist today, we'll never know about them

[/QUOTE]

Good post about the philosophy of science. Regarding abiogenesis I think we can say we just don't know at the moment. Although amino acids have been synthesised de novo using early earth conditions.

The_Captain

It's interesting that pretty much everything we know about prebiotics is based off the Miller-Urey experiment in the 1950s.

Even today, there's no clear consensus on what the early Earth conditions were in terms of the levels and composition of atmospheric content.

The modern take on it throws up more questions. Assuming that all amino acids on Earth were originally created on Earth (i.e. they didn't come here on an asteroid or some other extra-terrestrial source).

Why is all life based off 20 specific amino acids? Why aren't the others used? Why are L isomers so common while D isomers don't really occur naturally?

GerB40

The_Captain wrote: »

It's interesting that pretty much everything we know about prebiotics is based off the Miller-Urey experiment in the 1950s.

Even today, there's no clear consensus on what the early Earth conditions were in terms of the levels and composition of atmospheric content.

The modern take on it throws up more questions. Assuming that all amino acids on Earth were originally created on Earth (i.e. they didn't come here on an asteroid or some other extra-terrestrial source).

Why is all life based off 20 specific amino acids? Why aren't the others used? Why are L isomers so common while D isomers don't really occur naturally?

God did it..

osarusan

I've posted this before, but I'm constantly in awe of Paul bach-y-Rita and his work in neuroplasticity.

It seems to me to be such a great example of humanity's desire and ability to learn, try new things, solve problems, and help each other.

The Corinthian

Δt = t / SQRT(1 - (v^2 / c^2))

Rhys Essien

Cheese Wagstaff wrote: »

Not sure if it's strictly science, but I think this is a cool bit of information nonetheless:

Genghis Khan was so sexually prolific during his reign of terror, that the probability of any single person on the planet being a descendant of him is 0.005.

Speaking of Genghis Khan,every one of us has up to a billion atoms that once belonged to him.Likewise a billion more for Buddha,Beethoven and Shakespeare due to the fact that atoms are so vigorously recycled at death.

Every atom you possess has almost certainly passed through several stars and has been part of millions of organisms on its way to becoming you.

GerB40

Rhys Essien wrote: »

Speaking of Genghis Khan,every one of us has up to a billion atoms that once belonged to him.Likewise a billion more for Buddha,Beethoven and Shakespeare due to the fact that atoms are so vigorously recycled at death.

Every atom you possess has almost certainly passed through several stars and has been part of millions of organisms on its way to becoming you.

The same with water molecules. By the law of averages any time you drink tap water you're drinking molecules (I can't remember how many) that have passed through Ghengis Khan, Galileo, and basically any historical figure you can think of..

The_Captain

Not me, I've got one of those Brita filters

GrumpyMe

Rhys Essien wrote: »

...Genghis Khan,every one of us has up to a billion atoms that once belonged to him...

That could explain my temper,

Rhys Essien wrote: »

for Buddha

my girth,

Rhys Essien wrote: »

for Beethoven...

my hearing and

Rhys Essien wrote: »

and Shakespeare...

my bonce but only the shiny top!

fiachr_a

When people place metal objects on their skin and it sticks to them. I thought it was because they didn't wash and the sweat/dirt creates suction but they seem to have some kind of magnetic ability!

steddyeddy

The_Captain wrote: »

It's interesting that pretty much everything we know about prebiotics is based off the Miller-Urey experiment in the 1950s.

Even today, there's no clear consensus on what the early Earth conditions were in terms of the levels and composition of atmospheric content.

The modern take on it throws up more questions. Assuming that all amino acids on Earth were originally created on Earth (i.e. they didn't come here on an asteroid or some other extra-terrestrial source).

Why is all life based off 20 specific amino acids? Why aren't the others used? Why are L isomers so common while D isomers don't really occur naturally?

Well there are other amino acids for example selenocysteine uses a selenium atom instead of a sulpher atom in its side chain. Ornithine is another one. Formylmethionine is found in bacteria and immune cells sense this and migrate towards it in order to kill bacteria.

Some D-isomers do occur in nature but as you say the L form predominates. I think there is some evidence that the L form is energetically favorable relative to the D form. Just by a tiny fraction but it adds up with every amino acid.

_Tombstone_

Human vocal cords built from scratch in world first

Doctors have grown the world’s first vocal cords from scratch. The breakthrough could one day restore speech to people who have lost their own vocal cords through surgery or disease.

Doctors built the vocal cords using cells from human donors. The cells were coaxed into forming tissue that mimics vocal fold mucosa – the flaps in the larynx that vibrate to create the sounds of the human voice.

This is the latest success in the rapidly advancing field of tissue regeneration – the list of organs already includes kidneys, windpipes and hearts.

The donated vocal fold cells came from one cadaver and four patients who’d had their larynxes removed surgically for various reasons. The team grew the cells in the lab for two weeks to create 170 vocal folds, around 16 millimetres in length and a millimetre thick.

Researchers tested the vocal cords by attaching them to larynxes extracted from dogs. “We put the larynxes with the folds attached onto a fake windpipe and blew warm air through them,” said Nathan Welham at the University of Wisconsin School of Public Health in Madison, and head of the team behind the work. The result resembled a robotic kazoo, says Welham. “It was an eeee-like sound.”

The sound matches that made by natural human vocal folds in isolation, he explains, but a real human voice is generated through further modulation of sounds by other structures, such as the mouth and throat.

Hammer89

I still can't get my head around the fact we all started out as cumshots.