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Old 10-11-2014, 04:51 PM
 
Location: Westeros
90 posts, read 88,195 times
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Quote:
Originally Posted by ncole1 View Post
Well, I had watched some video on Youtube a while back about sulfur-reducing bacteria and some basic biochemical synthesis cycles, but I didn't quite follow it all. What are the chemical cycles to get from inorganic molecules to chemicals making up a cell, that are in place today?

I know that it's not hard to get to protein once you have amino acids, and to get DNA from its bases, but do bacteria living today really synthesize those things from scratch, like nucleic acids, and if so, what is the chemical pathway, and what carbon-containing molecule is the source? HCN? CH4? What is the sulfur source? H2S?

If you had a vat of just HCN, CH4, HCHO, H2S, etc. with no DNA or protein, and put the right bacteria in it, could they consume the available energy and multiply successfully?

What about if you started with the chemicals in the Miller-Urey experiment and their products? Any amino acids produced inorganically would presumably have equal mixtures of left-and right-handed molecules. Can presently living bacteria make use of the right chirality without the wrong handedness molecules getting in the cycle and messing it up?
Well, we're pretty sure that ALL life on Earth came from a combo of 20 or so amino acids that were the pre-cursors of proteins needed for cells to form, multiply and evolve. But I have to disagree with you that once ya get the aminos "it's not that hard to get proteins." Maybe not when they're made in animal cells, like in us, but insofar as the "primordial soup" scenario, this process has proved tricky.

But anyway..according to my favorite theory, chemical evolution occurred in four stages....

In the first stage of chemical evolution, molecules in the primitive environment formed simple organic substances, such as amino acids. (This concept was first proposed in the 1940s in a book entitled, "The Origin of Life on Earth," written by a Russian scientist who's name escapes me. Sorry. But He considered hydrogen, ammonia, water vapor, and methane to be components in the early atmosphere. Oxygen was lacking in this chemically-reducing environment. He stated that ultraviolet radiation from the Sun provided the energy for the transformation of these substances into organic molecules.
Scientists today think that such "spontaneous synthesis" occurred only in the primitive environment. Abiogenesis became impossible when photosynthetic cells added oxygen to the atmosphere. The oxygen in the atmosphere gave rise to the ozone layer which then shielded Earth from ultraviolet radiation. IMHO:THIS was the crucial step! Indispensable! No it = No US!
Newer versions of this theory still contend that the primitive atmosphere also contained carbon monoxide, carbon dioxide, nitrogen, hydrogen sulfide, and hydrogen. (Guess what?--Present-day volcanoes emit these substances)... pretty good point for validity!

The 1955 Miller-Ulrey experiment, for example, that you mentioned, tried to re-create early Earth's atmosphere about 3.5 billion yrs. ago with only water, hydrogen, ammonia, and methane and an electrical charge standing in for lightning, and produced complex organic compounds like amino acids. Now, scientists have learned more about the environmental and atmospheric conditions on early Earth and now think that the conditions used by Miller-Urey were quite a little skewed. (IMHO: coulda been their electrical charge not producing the ozone burning like reallighteningdoes) BUT, since Miller and Urey, many scientists have performed experiments using more accurate environmental conditions and exploring alternate scenarios for these reactions. These experiments yielded similar results - complex molecules could have formed in the conditions on early Earth.

all this work might help us learn the functioning of the RNA world too... For example, my former professor and biochemist, Andy Ellington, told me he thinks that in the early RNA world, RNA copied itself, not by matching individual units of the molecules (like modern DNA), but by matching short strings of units — it's a kinda like assembling a house from prefab walls instead of brick by brick. He's studying this idea by performing experiments to search for molecules that copy themselves like this and to study how they evolve. cool stuff!

Lastly: check out what this genomist named Venter has done (he of the Venter Genomics Insitute) with synthetic chemicals successfully used to create bacteria.I think he just did something very similar to your Q about a vat with no porteins or aminos, but only HCN, CH4, HCHO, H2S, etc...

http://blogs.plos.org/dnascience/201...-created-life/

finally: congrats! you have succssfully taken to the limits of my chemistry chops! From your question I'm thinkin' you are pretty well-versed in that discipline (you know about left-hand and right-hand molecules!) so...you have your own ideas on all this. I'd be interested in hearing them! kyle ruffin

Last edited by Ruffin_Ready; 10-11-2014 at 06:05 PM..
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Old 10-13-2014, 12:03 AM
 
Location: Auckland, New Zealand
5,508 posts, read 2,589,479 times
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Thanks, Ruffin_Ready.

Great thread!

May I ask about our Neanderthal friends? I saw a programme in which the Neanderthal was presented as having ginger hair and a pale skin, this information coming from DNA analyses. Is this factual or wishful thinking/guesswork? The program on the whole made sense to me but am I to believe the ginger hair and pale skin bit? It wouldn't surprise me since many people with the Neanderthal brow also have ginger hair and freckled pale skin. (Apparently, ginger haired, freckled skinned people have tougher skin than other people).
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Old 10-13-2014, 03:38 AM
Yac
 
5,874 posts, read 6,289,698 times
I read about it in iirc Focus: History (Polish edition), according to the theory presented Neanderthals had bigger brains, but also had much bigger eyes and too much brainpower was used up to .. well, use them. In comparison, Homo Sapiens had relatively more "free" brain power, despite having a smaller brain.
And yes, as you can see, I'm no scientists so please be gentle if I didn't use the terms correctly, I hope what I meant is clear
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Old 10-13-2014, 11:36 AM
 
Location: Westeros
90 posts, read 88,195 times
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Quote:
Originally Posted by Yac View Post
I read about it in iirc Focus: History (Polish edition), according to the theory presented Neanderthals had bigger brains, but also had much bigger eyes and too much brainpower was used up to .. well, use them. In comparison, Homo Sapiens had relatively more "free" brain power, despite having a smaller brain.
And yes, as you can see, I'm no scientists so please be gentle if I didn't use the terms correctly, I hope what I meant is clear

Hey Yac!!

No, no, your science is just fine and you seem to have understood exactly what you saw on the Focus programme.

Yeah, our Nenanderthal cousins DID have bigger skulls and overall larger brains than AMH's (anatomically modern humans) did, and do now. But! What ended-up being the crucial factor as to who finally prevailed--homo sapiens or them--is which part of the brain was better developed between the two groups.
See, the Neanders never really learned to improve socially, the way we did, which indicates that their big ol' brains developed very differently. We believe that they were more focused on pure individual survival, and not so much as developing groups or a society. They learned the hard way: "No man is an island." LOL

Neanders were bigger, stockier, physically stronger, more robust, and had more lean body mass (muscle) than AMHH's. So, like you said, Yac, a great deal of their brainpower went into controlling that body's robusticity. Their brains invested a lot of their power to the somatic nervous system (SoNs) which controls your muscle reflexes, coordination and body control. Also, Neander skull fossils have shown us they had bigger eye sockets (orbitals) than us, as well. So...bigger eyes means they had larger visual cortices--the part of the brain that interprets all those light-waves coming into the eye. Well, the part of the brain that houses all this equipment is in the back of the skull, and it's called the occipital lobe. (This is why, if you look at a picture or a Neander skull you see that most of its mass is in the rear, it doesn't taper down as drastically towards the back of the neck as ours.)

But this is important: we had better-developed frontal cortexes, which is the part of the brain where logic, social and reasoning skills come from!

So, yeah, I think it's pretty interesting--and lucky for us?-- that, while neanderthals were physically stronger and mentally more capable of controlling their bodies and vision, they eventually went extinct without AMH's evolved social skills. (This alone may not have actually caused their extinction--there's several theories concerning that, including the possibility that neanderthals and ancient humans interbred) but it's good to know we put our smaller brains to better use!

Last edited by Ruffin_Ready; 10-13-2014 at 12:45 PM..
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Old 10-13-2014, 11:51 AM
 
Location: Westeros
90 posts, read 88,195 times
Reputation: 141
Quote:
Originally Posted by 303Guy View Post
Thanks, Ruffin_Ready.

Great thread!

May I ask about our Neanderthal friends? I saw a programme in which the Neanderthal was presented as having ginger hair and a pale skin, this information coming from DNA analyses. Is this factual or wishful thinking/guesswork? The program on the whole made sense to me but am I to believe the ginger hair and pale skin bit? It wouldn't surprise me since many people with the Neanderthal brow also have ginger hair and freckled pale skin. (Apparently, ginger haired, freckled skinned people have tougher skin than other people).

Hey 303!!


There is a receptor gene that helps control the production of melatonin and skin color. I wanna say it's called the "melano-cortico-receptor" gene, or something close to that, and I believe the genome guys code it as MRC-1. Well, DNA analyzing has shown that neanderthalis had a mutation of this gene, which may have caused them to have pale skin.
What could be advantageous about this?

Well we now know that today's humans with paler skin--and thus, inherited this receptor gene--are more proficient at soaking up Vitamin D from the sunlight than are peoples with darker skin. This makes perfect sense, huh? Because, look at all those fair-skinned, blonde, blue-eyed people from colder climates that offer less annual sunlight--like Scandanavia and Sweden and Northern Europe. Pale skin! Whereas, go down to Mexico and South America, and of course, Africa, the skni darkens dramatically because this MRC1 receptor is less active and doesn't need to increase Vit. D absorption since sunlight is plentiful.

Awesome question! (I used to have an organic chemistry teacher in undergrad school named Karl Larssen who was Swedish and would burn easily on our California sun, so he was always slathering on sunscreen--I can still smell it!--and when we would tease him about it he's say, "Those damn MRC receptors!." We'd ask him what the hell he meant and he'd tell us to "look it up.")

Last edited by Ruffin_Ready; 10-13-2014 at 12:55 PM..
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Old 10-13-2014, 04:14 PM
 
49 posts, read 63,509 times
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What I can't understand is how a deadly virus like Ebola evolved in the first place?

From an evolutionary standpoint, a virus would be more likely to spread and proliferate if it's host were to survive an initial infection and come in contact with more hosts. So what evolutionary advantages would Ebola have in killing it's host so quickly at a 90% mortality rate and therefore reducing the opportunity to spread to more hosts?

Just doesn't make sense! At least a virus like HIV can simmer in a host DNA for many years before the host dies, therefore enabling the virus to have multiple opportunities to spread to new hosts. That makes perfect evolutionary sense.
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Old 10-13-2014, 11:06 PM
 
Location: Auckland, New Zealand
5,508 posts, read 2,589,479 times
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Thanks, Ruffin_Ready .

Interesting question, Burgher-Brad! I await the answer with eager anticipation. (This is an awesome thread!)

Here's an interesting snippet I read some years ago (thinking of Neanderthals having larger eyes), Africans have better forward visual acuity than Europeans but have a smaller peripheral range than Europeans. I put this to the test with an African friend and sure enough, he could read further way than I could (I have good eyes) and could not see as wide an arc as I could. Europeans have a 180 arc of vision. I forget what Africans have but it's not that far off.
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Old 10-14-2014, 11:07 AM
 
Location: Westeros
90 posts, read 88,195 times
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Quote:
Originally Posted by Burgher-Brad View Post
What I can't understand is how a deadly virus like Ebola evolved in the first place?

From an evolutionary standpoint, a virus would be more likely to spread and proliferate if it's host were to survive an initial infection and come in contact with more hosts. So what evolutionary advantages would Ebola have in killing it's host so quickly at a 90% mortality rate and therefore reducing the opportunity to spread to more hosts?

Just doesn't make sense! At least a virus like HIV can simmer in a host DNA for many years before the host dies, therefore enabling the virus to have multiple opportunities to spread to new hosts. That makes perfect evolutionary sense.

Man, you guys come up with some great questions. (I also find it interesting that when I taught a high school Biology 101 summer school class a couple years ago for some extra $$, some of the kids' most common questions were the ones we've talked about here so far. Also: a LOT of Rupert Sheldrake quesitons. Maybe we'll get to him later? LOL) Thank you!

So...yeah, those pesky viruses! They can be truly bad news and a lot of virologists--and biologists as well--think that it's more likely the "end of the world" could come from some sort of "superbug" than, say, nuclear holocaust. This is the old "The world may end with not a bang, but a whimper."
Let's hope they are wrong! (BTW: this thread is especially timely, right now, eh? What with the latest Ebola virus outbreak.) I just read an article this morning from the World Health Organization (WHO) website that claimed that West Africa could see a rise to 10,000 new cases a week, within just a couple months. Also, the lethality percentage of infected persons has grown to 70%.
Which brings us back to the topic at hand: If viruses are so smart, cunning, nasty, and adept at evolving, why the hell would they "want" to kill their hosts? This on the surface seems counter-intuitive, because of the hosts survived, they could help the little buggers propagate, right?

Well, maybe. But let's remember that Viruses don't usually kill the host. Think of the herpes viruses, for example, which reside in the body of the infected individual for life, without causing much problems except a occasional blister or rash.
The viruses that DO kill the host are indeed maladapted. And, yes, overly virulent strains could be said to suffer from "short-sighted" evolution--which is not uncommon among any evolved species, BTW. (but let's remember, evolution does not have a particular goal in mind)
Remember HIV-1 and HIV-2, for example! HIV-2 crossed over from apes to humans at earlier point, so by now it has become much less virulent and much less lethal - it is more of a chronic infection, than a deadly disease In contrast, HIV-1, which crossed over only few decades ago, is not yet adapted well to us - and causes the major health problem we witness.

Also recall that unlike bacteria, viruses are NOT living organisms. They are lifeless until they invade a living cell. (They are also way, way, smaller than bacteria, a fact we'll return to at the end of this post!)
They are basically just DNA encased in a protein shell, which we call a capsid.. They do not "live" off of the organisms they infect, they do not need food to survive. They can self replicate and spread easily from host to host. It's not exactly clear how viruses originated but there is some evidence that they could have been mutated organelles that have evolved. (you remember that an organelle is a mechanism within a cell, like the mitochondria). The viruis not "striving" to survive, it just is what it is. Like a computer virus, it lives to infect.
And, while it may not always kill its host it DOES kill the cells it invades and hijacks.

Going back to the "short-sightedness" of overly-lethal viral strains: Again: just like evolution do not really "have a plan." There was an old school theory that postulated evolution DID have "an ultimate goal in mind" and it's purpose was to evolve from "the bottom up", culminating in a "perfect species." This was called "the Teleological Theory" or the "Argument for Design." (Darwin never thought this, btw). But it doesn't work that way: it's all based on random mutations. There is no Master Plan. It's only when one of those random mutations proves advantageous to adaptation in the current environment that the "selfish gene" gets a chance to replicate further, since its hosts will thrive and thus live to pass the gene on to their progeny. Pretty soon the only ones left will be the hosts that were lucky enough to harbor that genetic mutation. So it becomes the norm. My favorite Mantra on the mechanics of Evolutions: "Variation; Replication; Selection."

OK--going back to how small viruses are, you guys should click on this link and do the interactive "mouse slide." It's pretty amazing! As you navigate from the head of the pin all the way down to the virus, keep in mind what they can do to a full-grown human. It's pretty impressive. (And forgive me for rambling, but Virology has always fascinated me!

How Big is a ... ?

Last edited by Ruffin_Ready; 10-14-2014 at 11:26 AM..
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Old 10-14-2014, 11:28 AM
 
1,176 posts, read 1,896,365 times
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Quote:
Originally Posted by sandman249 View Post
I have read the selfish gene - one of my favorite books.

Now getting back to this topic. I don't understand how a "smaller" or a "less intelligent" brain could have been such a BIG disadvantage for Neanderthals who were already highly evolved. Smaller and less intelligent compared to early humans? Sure. But were they less intelligent than the rest of the mammals who not only survived, but thrived.

Compared to other intelligent mammals (e.g. chimps), Neanderthals were almost early human-like - capable of building tools, etc. Maybe less intelligent, but definitely possessing the physical advantage (i.e. stronger vs early humans).
Two species that occupy the same niche are necessarily competing with one another when they occupy the same area. If one species has an advantage it will necessarily displace the other absent adaptation. Neanderthals were probably plenty clever, but we know a thing or two about human deviousness and capacity for being very rude, don't we? Does it really matter if a neanderthal male of your approximate age would have been significantly stronger than you if you knew how to fashion an atlatl that was beyond his comprehension?
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Old 10-14-2014, 11:50 PM
 
49 posts, read 63,509 times
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Quote:
Originally Posted by Ruffin_Ready View Post
Going back to the "short-sightedness" of overly-lethal viral strains: Again: just like evolution do not really "have a plan."
Well, evolution doesnt "have a plan" but the fundamental mechanism of evolution is to weed out species that can't survive and reproduce in a particular environment. Killing a host seems to be a good way to prevent increased viability and survivability. So viruses like Ebola seem to go against this most fundamental tenet of evolutionary theory!

Just don't make any sense! I'm almost willing to believe Ebola is some kind of alien species seeded here on Earth from some other source in the solar system. LOL, weird to say but seems to be no other plausible explanation.
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