biochemists

"In bacteria, the DNA forms into a long and twisted loop. The contorted tracks... close... to form a singular circular . In eukaryotic cells, there are usually a number of different chromosomes... each has two separate ends."

"The sequence of letters in a specifies the sequence of s in a protein. If the sequence of letters is changed—a —this may change the structure of the protein (...not always, there is some redundancy... technically degeneracy..—several combinations... can code for the same amino acid.)"

"The information encoded in DNA spells out the molecular structure of s. This, said Crick, is the 'central dogma' of all biology: genes code for proteins."

"[N]o bacteria coat their DNA with s: their DNA is naked. The histones not only protect eukaryotic DNA from chemical attack, but also guard access to the genes."

"[W]e are biochemically quite simple in comparison bacteria. Simpler than bacteria. In terms of our metabolic biochemistry we are really limited. ...[W]e have ...across the entire domain of s, about the same degree of metabolic sophistication as a single bacterial cell."

"I would define complexity, not really as genetic complexity because if you take it purely as genetic complexity, E. coli... a single cell may have 4,000 genes but the metagenome, the pool of genes in E. coli around the place may be on the order to 30,000 or more... [T]hat's the level of complexity equivalent to the human genome, or even more complex than the human genome, but it's organized and structured in a different way. ...You might say that it's structured in a similar way to an ... but I think an ant colony has taken that level of Eusocial behavior a long way beyond anything you would see in E. coli. So I would define it as morphologically complex, meaning cells are larger and have a lot of stuff in them."

"They [bacteria] haven't used it [their more complex metabolism]... to give rise to more complex morphologies beyond the kind of stromatolite type structures, beyond s. That seems to be a limit. Some multicellularity, some degree of differentiation and complexity, but nothing... to compare with the flea."

"I think we share consciousness right across... not just even the animal world. I would see it going down even to the level of cells, some kind of flickering of consciousness. So I don't feel alone on earth, but I do think that there is something different about humans."

"[W]e can't agree among ourselves, as an origins of life community, what were the conditions... under which life arose on earth. ...Within the field itself, probably the leading candidate... would be terrestrial geothermal systems, starting with and powered by UV radiation. There's been a lot of rather beautiful chemistry... in a terrestrial environment in some kind of geothermal pool... and cyanide chemistry, it works well as chemistry. The problem I have with that is that it doesn't link up very well to biochemistry of cells. I'm a biochemist and I would like to see some continuity between and , and there's not much there, to me. That doesn't mean that it's wrong. It's just that... [I] would like to see some continuity."

"What does life do then? ...it seems reasonable that the earliest forms of life were ic... [i.e.,] they grew from gases... found in normal geological environments through an energy flux which is equivalent to cells which we see today, which is to say, what all life does today. There's a very simple phrase from Mike Russell... "hydrogenate CO2"... [i.e.,] add onto to make organic molecules. That is the structure of in cells, and different cells can get hydrogen from all kinds places. They can strip it out of water. They can get it from , but it also comes bubbling out of the ground as hydrogen gas, and that seems to be the simplest form of life imaginable as... life on earth. It's reacting hydrogen and CO2, and they don't react easily. The way that cells make them react... is to effectively use an electrical charge on a ... [T]here are environments like deep sea s that provide... for free with an equivalent electrical charge across a barrier, and I think... that's the way to see the question."

"Now it's possible to have some kind of protocell with some form of metabolism without any genetic heredity. It's possible in principle. Is it alive?"

"I read some of those ideas years ago, , and thought it was thrilling. Over recent years I don't really see the need for a kind of genetic intermediary between an RNA level of genetic replication and some other form of replicator. ...[T]here's no suggestion that it's there in biology. There's no suggestion that I know from geology that is capable of giving rise to more complex systems, or to having an organic takeover. It seems to add in a layer of unnecessary complexity. So I much prefer to get straight into organic chemistry, and straight into as we know it."

"It is the movement that creates the form."

"became the study of how... simple molecules were interconnected one into another. ...The [simple] molecules ...containing ...up to about twenty carbons, but most ...have fewer than ten."

"In Transformer, Lane indulges in a great many of the banes of popular science writing... These kinds of over-earnest attempts to defang a complicated subject are an enduring mystery; the people who need them won't read the book, and the people who'll read the book don't need them. ...Fortunately, Lane’s discussion ...is itself very winningly animated, and that saves it ...Lane’s personal excitement ...goes a long way toward making ...biochemistry comprehensible ...[T]his is done through personalities; Transformer is as much about the people investigating the Krebs cycle as it is about the cycle ...That kind of personality pervades the book and makes it ...consistently fascinating reading."

"[M]ost of what I teach and interact with the students is more about life on earth and the principles governing evolution, and from my own point of view, the biochemical side, which is not normally part of the evolutionary biology... [I]t's relatively rare for me to discuss life elsewhere in the Universe with them."

"[On the controversy between and .] [T]he classic case of convergence would be the eye and the human eye, or ian eyes. ...The common ancestor they had had a light sensitive spot, they did have some regulatory genes in common... for example, but that had to effectively independently recruit all the rest of the genes required to make a camera type eye, and that direction of evolutionary travel was in parallel. It was convergent. We even see in some s... a camera-type eye in single-celled critters where there's a retina made from s. There's a made from mitochondria. There's a there. They don't have a brain. I don't know how they use this thing but... plainly it's a camera-type eye. ...It's a of some sort. ...I would see that as a completely independent origin of a camera-type eye, albeit without a brain. I would see the octopus' and mammalian eye as being convergence in the Simon Conway Morris sense... There are certain ways that you can make an eye, that work, and all the steps along the way have to be favored, and... perhaps there are seven or eight... fundamentally different types of eye that we see on earth, and most of them have arisen more than once, always from a common ancestor, generally, that had as a light sensitive pigment. So you're then into an interesting terrain or... How common are the right types of light sensitive pigment? They're chemically not so straight forward."

"Thew problem here for me is that I'm in a biology department and is still somewhat frowned upon by a lot of biologists who would see it as a form of speculation. So the courses that I teach are about life on earth and they're not so much about life in the Universe... [I]t is something that I should develop, I think."

"I've been asked on various occasions, "Why don't we, as an origins of life community, get together, think what a killer experiment is, and then go and build a or something, where we go and do the experiment?" And the answer to that is... [W]e can't agree with each other about what experiment would you do? ...[I]t is intrinsically a lot more complex, precisely because it's a continuum. We don't know. We don't agree about what environment, we don't agree about what kind of chemistry or biochemistry. We can't join these things up, and so it seems to me a much healthier environment is to be deliberately multiple about it. Not to say, "Ok, this particular world view is going to dominate." I think we have to have multiple views until we know more."

"There are people at UCL, Ian Crawford, who's doing a great deal for , but it's not something which is happening through my department. It's happening through s. It's not happening in biological sciences..."

"Flux is a form of flow, but with one crucial difference. ...In biochemistry flux is the flow of things that are transformed along the way."

"[B]iochemical pathways that produce the basic building blocks of life are... conserved across practically all cells."

"I read a book called The Vital Question. ...A few months later... I had also ordered Nick’s three other books, read two of them, and arranged to meet him in New York City. ...He is one of those original thinkers who makes you say: More people should know about this guy’s work. ...Nick is talking about how getting energy right at the cellular level explains how life began, and how it got so complex. ...I'm intrigued by the practical applications of Nick’s work. Mitochondria could play a role in diseases like cancer. ...[O]ur foundation’s global health team is talking to Nick about the potential implications for the fight against malnutrition. ...[T]here’s no telling whether his specific arguments will turn out to be right. But even if they don’t, I suspect his focus on energy will be seen as an important contribution to our understanding of where we come from, and where are we going."

"The s were acquired by a eukaryotic cell that was already a fully fledged eukaryotic cell."

"I would say that if there's a probability of life being cellular, which I think there is. Life being based, which I think there is. Life starting out with CO2 because it's so common in planetary atmospheres, and , which is very common, from the kind of s which I'm talking about... and liquid water. They need liquid water for , but we know of it on ... on Europa... [Serpentinization] is giving rise to alkaline fluids with hydrogen gas. Most hydrogen gas you find in planetary atmosphere are coming from serpentinization. , which is the mineral required for that... is ubiquitous in interstellar dust... So all of this pushes you down a certain avenue, and if that's correct it gives you bacteria... and if that's correct then bacteria have a structural problem, and they're not going to get beyond bacteria except with an endosymbiosis, and that in itself is improbable, unlikely... because it only happened once, to our knowledge, on earth."

"[A]cquiring mitochondria gives you a headache that can go wrong very easily, but here's an interesting problem in a nutshell. You look at a plant cell under a microscope, or an animal cell, or a fungal cell, or an or something, and you'll recognize the same structure in all of them. They've all got a nucleus. They've all got the s as straight chromosomes. They've all got s. They've all got s. They've all got complexes. They all do as a division mechanism. They all do as two steps where you first double everything and then half it twice. They all go through the same rigmarole. They've all got mitochondria. They've all got the same system, endoplasmic reticulum, things like that. ...[Y]ou could list page after page after page in a text book and it would be exactly the same for a plant, or a fungal cell, or an animal cell. Now they have really different ways of life. If you were to simply think, "Well, there's some inevitability that bacteria will give rise to complex life." ...You would imagine that a photosynthetic bacteria, a would give rise directly to photosynthetic , eukaryotic algae, but they didn't. It was by the intermediary of acquisition of a . There was a common ancestor of eukaryotes that was nothing like a cyanobacterium and nothing... quite like an algae except without the chloroplasts. So... why is it that we all have the same machinery inside, but we have such different lifestyles? Why don't we see multiple origins of complex life where cyanobacteria give rise to photosynthetic trees? Why don't we see predatory bacteria?"

"What I would say with some degree of certainty from the example of life on earth, is that if you simply have a population of bacteria... the chances of it giving rise to the kind of morphological complexity... we see in eukariotic cells, and we do not see in bacteria, is remote... because bacteria and archaea, if you look at the amount of , they dwarf the genetic variation that we see in Eukaryotes. They have explored genetic sequence space to orders of magnitude greater that Eukaryotes did, and despite exploring all of that space, they haven't come up with morphological complexity. ...[T]hey did through an endosymbiosis. ...It's rare between prokaryotes, rare to the point that we know of one example of free-living bacteria with bacterial cells living inside it. We know of two other examples where, there's a for example, which has inside its own cells... some gamma protein bacteria, with beta protein bacteria living inside them. It's a little bit of a strange system and it's hard to know, again, can you generalize from this, because it's all inside a Russian doll?"

"The only way that you can really get a selfish replicator to be unselfish is to put it in a bag with a bunch of other selfish replicators, and then they're more or less obliged to cooperate."

"[T]he contends that ageing and many of... [its associated] diseases... are caused by... free radicals leaking from mitochondria during normal . ...As they burn up food using oxygen, the free-radical sparks escape to damage adjacent structures ...Many cruel inherited conditions... are linked with mutations caused by free radicals attacking mitochondrial genes."

"I like philosophers. I think they can teach scientists how to think very often, and... there's a lot of sloppy thinking among scientists, and I think philosophers can be quite rigorous about it. It gets a lot of scientists cross with philosophers who don't engage with science, but I think there are more philosophers these days who are engaging in a serious way with science. I think they have important things to say."

"[I]t's interesting to me that the bacteriophages, the viruses that you find in bacteria, are not remotely similar to the ones that you find infecting archaea, which again are not remotely similar to eukaryotic viruses. ...They're different in their appearance. They're different in their mechanisms in which they force their... I mean the bacteriophages are these classic lunar module landing things... They are stunning things to look at. ...Some es look like bottle balls or postage stamps, strange shapes... They don't have any genes in common. They don't have mechanisms of entry into cells in common. They appear to be independently derived."

"That's why they [viruses] are not in the tree of life. They don't relate in a very direct way. ...[T]he tree of life now is not only about ribosomes. You can build trees from whole genomes, but viral genomes? They don't really fit in, in a way which makes sense to people."

"[Martin Rees] may be right. If we were to go back 5 million years, as intelligent apes, and ask ourselves "What is postbiological life?" I think the answer is it's not a concept that would possibly mean anything. So we've had... 4 billion years of life on earth, and it's come up with an enormous wealth and variation, but it's all organic and... the chances of it coming up with humans? I can't put a number on that. ...I don't think there's an inevitability that life, once it's started will give rise to a human-like intelligence or beyond that. I think there's nothing inevitable about it, and if we just go back a few million years on earth, there was nothing inevitable about it. So I, personally would still look for organic life, but... I'm not sure that would be the easiest thing to find. It may be that it's easier to find, yes, nano aliens or something."

"It requires that life elsewhere should be modeled along similar lines to life here, which is that it should be cellular, it should be carbon-based. It should be in water. If those things are not true, then there's no reason why that numbers game would apply anywhere else. But if those things are true, then yes, I think the fact that photosynthesis only arose once, that Eucaryotes only arose once, that what Nick [Nicholas J.] Butterfield calls organ grade multicellularity, which is to say quite serious differentiation with scores of different cell types and specializations. We don't see that in fungi. We don't see that in algae. ...[Y]ou see two or three different types of cell. So that's rare. It's in plants and it's in animals. It begins to look less likely. I think it's reasonable to say it's less likely, but I wouldn't like to rely too much or put too much weight on it."

"I do like this quote from Simon Conway Morris that if the aliens call then don't pick up the phone. I'm not sure I'd really like to meet any of them very much. Perhaps... meeting bacteria would be the least scary... [T]he chances of meeting aliens is so remote that I haven't really troubled myself very much about it. It would be nice to think that if we did, somehow they would be a superior intelligence... they would have solved a lot of the problems of aggression and whatever else that humans have, but I fear not. I fear that it would be the opposite, that... natural selection has a knack of producing nastiness in intelligence."

"Does anyone care if there's an awful waste of space? It's a form of wishful thinking... We would love for the Universe to be full. ...Personally, I grew up on the Hichiker's Guide to the Universe, those kind of crazy science fiction yarns, or Star Wars or whatever it may be. The idea that the Universe is full of other intelligent beings, all kind of finding a way of getting along or having a war, but having some heroism thrown in, but... it's all human vision of ourselves thrown onto a cosmic scale. Do I believe any of it? No... Is there anything that I think, from my understanding as a biologist, that would tend to lead to that? No... Does it matter if it's a tremendous waste of space? Well, that's to say "What's the point of the Big Bang?" I don't know. The idea that the Universe may be completely empty apart from matter and energy? It would seem to be, perhaps, the default hypothesis. The fact that we find life is surprising. It would be nice if there were laws of the Universe that tended to give rise to life. Maybe there are at the level of bacteria. I don't see it at the level of large, morphologically complex beings... I think it's emotive. It's pleasing, but I doubt it's true."

"According to mitochondrial gene analysis, man didn't interbreed with Homo Sapiens..."

"For decades, biology has been dominated by information—the power of genes. ...[Y]et there is no difference in the information content of a living protozoon and one that died ...The difference between alive and dead lies in energy flow ...the ability of cells to continually regenerate themselves from simpler building blocks."

"I've had long and sometimes difficult discussions, especially about the singularity of the origin of Eukaryotes... A lot of people don't like that. ...[I]t's not really about what does it say about the probability of life elsewhere, although it has things to say to that. It's really about life on earth, and a lot of people are very uncomfortable with the idea of improbability... I've had quite difficult discussions with some students about that, but rarely... about life elsewhere in the Universe."

"I see myself as a biologist or a biochemist, but... in the context of as a broader subject, it forces me to wrestle with physics, with cosmology, with chemistry, with geology, with earth sciences or planetary sciences, and that's a thrill. ...I think it's what most people are drawn into science in the first place for, because science, in its biggest sense, is what inspires people, and by the time that you've got to the level of doing a PhD, it's narrowed down so much that a lot of people are almost forced to lose their imagination, and their creativity as a scientist... I think astrobiology is a subject that puts all that back in, in heaps."

"Even the laws of thermodynamics... can be recast in terms of information — Shannon entropy, the laws of bits of information. But this view generates its own paradox at the origin of life. ...Place information at the heart of life, and there is a problem with the emergence of function ...the origin of biological information. There are problems... in understanding why we age and die... diseases... and how experiences can give rise to conscious mind. ...A far better question ...what processes animate cells and set them apart from inanimate matter?"

"Mitochondria are a badly kept secret. ...There are usually hudreds or thousands of them in a single cell, where they use oxygen to burn up food. ...[O]ne billion ...would fit comfortably on a grain of sand."

"The is riddled with redundancy."

"The driving force of is thermodynamics. ...[I]n this context ...the chemical need to react (to dissipate energy) in the same way that water needs to flow downhill."

"This membrane, so vanishingly thin, looms large... for bacteria use it for generating their energy."

"The possessors of... nuclei, the s, are the most important cells in the world. ...[A]ll plants and animals, all and fungi... essentially everything we can see with the naked eye, is composed of [them]..."

"[A]ll multicellular plants and animals... contain mitochondria."

"[A]fter a decade of careful , it looks as if all known eukaryotic cells either have or once had... mitochondria."

"[T]he mechanism by which mitochondria generate energy, by pumping protons across a membrane (), is found in all forms of life... It's a bazarre way... This idea, however... won Peter Mitchell a Nobel Prize..."

"So there's one example of free living ... with bacteria living inside it. It wasn't . It's got a cell wall and it's not a . So they can get inside, but we can say for sure it's rare. What does it do? In a nutshell it changes the topology of the cell. It allows you to internalize respiration and it's not just internalizing the membranes. It's internalizing a genetic control system with in our own case, which by standard selection is whittled down to a kind of minimal unit required to do the job, and that in effect allows the nuclear genome to expand up to anything it wants to be. So... it's a structural change. It's not something which you can find by genetic exploration of the evolutionary space. It's something [in] which you change the topology of a cell. And once you've got that, you've got bacteria living inside another bacterial cell. You've got a fight on your hands! They've got to get along with each another somehow. So the chances of it going wrong is quite high. So I would imagine if we know of one or two examples now, there must have been thousands, millions, billions of cases of this over earth history. The fact that... all this searching across the earth that we've done for life, we find bacteria, we find , we find these candidate phyla. We're not sure what they are, exactly, but they seem to be very simple and probably s, and we see Eukaryotic cells, all the cases that appear to be potentially evolutionary intermediates, something slightly different, have turned out to be highly derived... from more complex ancestors."