1 00:00:11,770 --> 00:00:09,040 welcome to the final day of pak-rat calm 2 00:00:14,350 --> 00:00:11,780 and thank you for making it this fairly 3 00:00:17,290 --> 00:00:14,360 on the final day of wealth sign state 4 00:00:18,460 --> 00:00:17,300 about going on why do I want one of the 5 00:00:20,380 --> 00:00:18,470 organizers and I'm going to be giving 6 00:00:23,380 --> 00:00:20,390 you a warm talk today that's kind of a 7 00:00:26,140 --> 00:00:23,390 crash course in biochemistry and the 8 00:00:27,970 --> 00:00:26,150 origins of life which you know I can 9 00:00:33,729 --> 00:00:27,980 totally government 30 minutes right um 10 00:00:35,350 --> 00:00:33,739 so completely blatantly I have liberally 11 00:00:37,660 --> 00:00:35,360 bharadwaja mayor Goldman and 12 00:00:40,900 --> 00:00:37,670 grasshoppers so lovely neither of them 13 00:00:43,779 --> 00:00:40,910 are here today look no so if any of you 14 00:00:48,910 --> 00:00:43,789 rather last year you may see some 15 00:00:51,309 --> 00:00:48,920 similar stuff um so first off I think a 16 00:00:52,930 --> 00:00:51,319 lot of presentations should probably 17 00:00:55,540 --> 00:00:52,940 have this the why do we care slide so 18 00:00:57,969 --> 00:00:55,550 this is gold three from the astrobiology 19 00:01:00,069 --> 00:00:57,979 roadmap so you know I'm going to be 20 00:01:01,360 --> 00:01:00,079 talking today and a lot of people are 21 00:01:03,579 --> 00:01:01,370 going to be talking today about life on 22 00:01:06,490 --> 00:01:03,589 Earth but why do we care alive America 23 00:01:09,370 --> 00:01:06,500 looks like life else but really has to 24 00:01:12,010 --> 00:01:09,380 do with we work with what we got kind of 25 00:01:14,679 --> 00:01:12,020 thing so we have this really beautiful 26 00:01:16,840 --> 00:01:14,689 complex system of life on Earth and the 27 00:01:20,350 --> 00:01:16,850 better that we understand it the better 28 00:01:22,420 --> 00:01:20,360 that we are able to know what to look 29 00:01:24,819 --> 00:01:22,430 for elsewhere in terms of bio signatures 30 00:01:27,100 --> 00:01:24,829 in terms of you know maybe what microbes 31 00:01:29,139 --> 00:01:27,110 look like that sort of thing so that's 32 00:01:30,609 --> 00:01:29,149 essentially why you're going to have a 33 00:01:34,840 --> 00:01:30,619 lot of people today talking about how 34 00:01:37,300 --> 00:01:34,850 life arose on earth this is the tree of 35 00:01:42,399 --> 00:01:37,310 life in even this is a pretty simplified 36 00:01:45,940 --> 00:01:42,409 version so we are I mean today modern 37 00:01:47,649 --> 00:01:45,950 biology is kind of here but I'm not 38 00:01:49,270 --> 00:01:47,659 going to talk about that at all today so 39 00:01:52,450 --> 00:01:49,280 these are all the interesting stuff 40 00:01:53,709 --> 00:01:52,460 we're in here plants East yeah now going 41 00:01:55,480 --> 00:01:53,719 to talk about any of that Jennifer is 42 00:01:58,330 --> 00:01:55,490 going to talk about that right after me 43 00:02:02,950 --> 00:01:58,340 so I'm going to go back here actually 44 00:02:04,899 --> 00:02:02,960 before here three four billion years ago 45 00:02:07,599 --> 00:02:04,909 depending on who you believe and I'm not 46 00:02:11,100 --> 00:02:07,609 going to get into that argument to the 47 00:02:15,460 --> 00:02:11,110 last Universal common ancestor which is 48 00:02:17,710 --> 00:02:15,470 essentially not necessarily one single 49 00:02:19,300 --> 00:02:17,720 cell that from which all life on Earth 50 00:02:23,440 --> 00:02:19,310 evolved from 51 00:02:26,140 --> 00:02:23,450 probably a population of cells with 52 00:02:28,540 --> 00:02:26,150 really rapidly changing or exchanging 53 00:02:31,300 --> 00:02:28,550 information so which is called the 54 00:02:33,280 --> 00:02:31,310 horizontal gene transfer today so the 55 00:02:35,110 --> 00:02:33,290 idea there is that the information can 56 00:02:37,780 --> 00:02:35,120 go back and forth really quickly and so 57 00:02:41,979 --> 00:02:37,790 things were happening very fast until at 58 00:02:43,870 --> 00:02:41,989 some point whether it was a physical 59 00:02:47,800 --> 00:02:43,880 barrier something that came up between 60 00:02:52,170 --> 00:02:47,810 the this ancestor and the ancestor of 61 00:02:56,710 --> 00:02:52,180 all bacteria or something chemical 62 00:02:58,690 --> 00:02:56,720 anyways caused caused the divergence so 63 00:02:59,800 --> 00:02:58,700 but yeah like I said I'm not going to 64 00:03:02,080 --> 00:02:59,810 talk about any of that today I'm going 65 00:03:05,470 --> 00:03:02,090 to basically try and get you from the 66 00:03:08,229 --> 00:03:05,480 origin of life which is here somewhere 67 00:03:12,820 --> 00:03:08,239 over here maybe to the last Universal 68 00:03:14,500 --> 00:03:12,830 common ancestor so one thing that is 69 00:03:17,979 --> 00:03:14,510 common the one thing we look at when 70 00:03:19,660 --> 00:03:17,989 we're trying to figure out the traits of 71 00:03:20,979 --> 00:03:19,670 the last Universal common ancestor are 72 00:03:23,110 --> 00:03:20,989 things that are common to all of life 73 00:03:24,940 --> 00:03:23,120 today this is the central dogma of 74 00:03:27,759 --> 00:03:24,950 molecular biology this is why our bodies 75 00:03:29,860 --> 00:03:27,769 work and it's common to all life on 76 00:03:33,160 --> 00:03:29,870 Earth so you have it protists have it 77 00:03:35,559 --> 00:03:33,170 everything so the way that this works is 78 00:03:38,319 --> 00:03:35,569 that you have double stranded DNA which 79 00:03:41,949 --> 00:03:38,329 is our information storage long-term 80 00:03:43,479 --> 00:03:41,959 storage it gets turned into RNA in a 81 00:03:44,710 --> 00:03:43,489 process called transcription or copied 82 00:03:48,789 --> 00:03:44,720 into RNA in a process called 83 00:03:50,229 --> 00:03:48,799 transcription and then RNA is sort of 84 00:03:53,620 --> 00:03:50,239 the short-term memory of life and it 85 00:03:54,670 --> 00:03:53,630 carries that information to a complex 86 00:03:56,559 --> 00:03:54,680 which we'll talk about a bit a little 87 00:03:58,390 --> 00:03:56,569 bit later which makes proteins proteins 88 00:04:01,300 --> 00:03:58,400 are what do the majority of the work in 89 00:04:03,550 --> 00:04:01,310 your body you know making all the 90 00:04:05,500 --> 00:04:03,560 molecules that you need to survive so 91 00:04:07,030 --> 00:04:05,510 yeah because this is common to all life 92 00:04:08,349 --> 00:04:07,040 on earth we can probably say that it was 93 00:04:10,599 --> 00:04:08,359 pretty well established in the last 94 00:04:12,580 --> 00:04:10,609 Universal common ancestor as well but 95 00:04:15,430 --> 00:04:12,590 let's get a little bit more familiar 96 00:04:18,819 --> 00:04:15,440 with these guys sorry oh I should say 97 00:04:20,050 --> 00:04:18,829 this happens sometimes if you want to 98 00:04:21,340 --> 00:04:20,060 talk about viruses but nobody stock 99 00:04:24,969 --> 00:04:21,350 remove iris is today so I could ignore 100 00:04:27,520 --> 00:04:24,979 it where RNA gets transcribed back into 101 00:04:30,870 --> 00:04:27,530 DNA so yeah let's get a little bit more 102 00:04:32,740 --> 00:04:30,880 familiar with life life is based around 103 00:04:35,740 --> 00:04:32,750 polymers at least 104 00:04:39,280 --> 00:04:35,750 terms of the molecules involved in that 105 00:04:42,040 --> 00:04:39,290 central dogma so DNA is a polymer of 106 00:04:43,740 --> 00:04:42,050 this big long word deoxyribonucleotides 107 00:04:45,730 --> 00:04:43,750 all that means is that you have 108 00:04:48,370 --> 00:04:45,740 nucleotides that are attached to ribose 109 00:04:49,540 --> 00:04:48,380 sugars that are missing an oxygen at one 110 00:04:51,550 --> 00:04:49,550 position I'll show you the chemical 111 00:04:52,960 --> 00:04:51,560 structures of those in a minute proteins 112 00:04:54,250 --> 00:04:52,970 are polymers of amino acids we've 113 00:04:56,560 --> 00:04:54,260 already heard a lot of people talk about 114 00:04:58,600 --> 00:04:56,570 amino acids and where they could have 115 00:05:02,790 --> 00:04:58,610 come from whether their stellar in 116 00:05:06,070 --> 00:05:02,800 origin or earthbound in origin and then 117 00:05:07,900 --> 00:05:06,080 starches which are probably a little bit 118 00:05:11,230 --> 00:05:07,910 later addition but are still a 119 00:05:13,630 --> 00:05:11,240 biopolymer that all of these are 120 00:05:18,130 --> 00:05:13,640 products of dehydration reactions so the 121 00:05:21,040 --> 00:05:18,140 monomers lose a water and then they form 122 00:05:24,100 --> 00:05:21,050 these long-chain polymers sounds easy 123 00:05:26,440 --> 00:05:24,110 not really but in so in terms of the 124 00:05:29,830 --> 00:05:26,450 full chemical structure let's go for DNA 125 00:05:32,500 --> 00:05:29,840 and RNA first so this is DNA this is RNA 126 00:05:36,070 --> 00:05:32,510 the only there's only two differences 127 00:05:38,200 --> 00:05:36,080 here let's see first off I'm going to 128 00:05:40,540 --> 00:05:38,210 say that I want you to kind of consider 129 00:05:42,550 --> 00:05:40,550 these in sort of modular units today so 130 00:05:44,650 --> 00:05:42,560 there's these backbones which are 131 00:05:46,870 --> 00:05:44,660 exactly what they sound like they 132 00:05:48,930 --> 00:05:46,880 connect all of the informational units 133 00:05:51,880 --> 00:05:48,940 to each other they're made up of 134 00:05:56,760 --> 00:05:51,890 repeating phosphate groups and ribose 135 00:06:00,760 --> 00:05:56,770 sugar ribose is a five carbon sugar and 136 00:06:02,890 --> 00:06:00,770 so in the case of DNA there's no oxygen 137 00:06:04,900 --> 00:06:02,900 at this position it's just a hydrogen at 138 00:06:07,360 --> 00:06:04,910 this Kate position you have an O H so 139 00:06:10,510 --> 00:06:07,370 that's why this is a ribose sugar this 140 00:06:13,480 --> 00:06:10,520 is a deoxyribose sugar these are the 141 00:06:16,300 --> 00:06:13,490 actual informational units that make up 142 00:06:18,760 --> 00:06:16,310 our genetic code these are the short 143 00:06:22,060 --> 00:06:18,770 forms for themselves adenine and guanine 144 00:06:25,450 --> 00:06:22,070 are what are called purines which have 145 00:06:27,910 --> 00:06:25,460 these two rings aromatic rings and then 146 00:06:31,360 --> 00:06:27,920 you have cytosine thymine and uracil 147 00:06:37,240 --> 00:06:31,370 which are these just have the one six 148 00:06:39,430 --> 00:06:37,250 membered ring oh and the other 149 00:06:41,380 --> 00:06:39,440 difference is that thymine is a little 150 00:06:43,300 --> 00:06:41,390 bit different than your so if I mean has 151 00:06:47,429 --> 00:06:43,310 a methyl group right here your soul does 152 00:06:50,830 --> 00:06:47,439 not feel free to bait why 153 00:06:52,480 --> 00:06:50,840 so the big questions in terms of origins 154 00:06:54,399 --> 00:06:52,490 of life were why were any of these 155 00:06:55,929 --> 00:06:54,409 components chosen so why do we have a 156 00:06:58,209 --> 00:06:55,939 phosphate here why do we have a ribose 157 00:07:01,689 --> 00:06:58,219 here and why are these bases what they 158 00:07:04,510 --> 00:07:01,699 are and another big question is modern 159 00:07:06,640 --> 00:07:04,520 life uses only d sugars I don't really 160 00:07:08,589 --> 00:07:06,650 want to get into stereochemistry but 161 00:07:09,820 --> 00:07:08,599 said stereochemistry is basically 162 00:07:15,820 --> 00:07:09,830 molecules can have two different 163 00:07:17,439 --> 00:07:15,830 handedness so if you have a molecule or 164 00:07:20,399 --> 00:07:17,449 an atom carbon atom that has four 165 00:07:22,719 --> 00:07:20,409 substitutions it can either have one 166 00:07:25,089 --> 00:07:22,729 configuration this way so my carbon 167 00:07:30,450 --> 00:07:25,099 atoms here I can have my three arranged 168 00:07:33,249 --> 00:07:30,460 this way or yeah all right 169 00:07:36,550 --> 00:07:33,259 stereochemistry we can talk about it 170 00:07:39,339 --> 00:07:36,560 later if you really want so yeah but 171 00:07:44,320 --> 00:07:39,349 basically yeah one of the big questions 172 00:07:46,029 --> 00:07:44,330 is why only d sugars into a little bit 173 00:07:48,700 --> 00:07:46,039 more detail so there's a 3d structure of 174 00:07:50,800 --> 00:07:48,710 in this case DNA but here you can 175 00:07:53,290 --> 00:07:50,810 actually see how the information is 176 00:07:54,670 --> 00:07:53,300 transferred from the two different 177 00:07:57,399 --> 00:07:54,680 strands or told you DNA is 178 00:07:59,490 --> 00:07:57,409 double-stranded so that these are base 179 00:08:02,890 --> 00:07:59,500 pairing interactions where their 180 00:08:05,680 --> 00:08:02,900 complementary so thymine right here can 181 00:08:09,129 --> 00:08:05,690 base pair to a Dineen with these two 182 00:08:13,029 --> 00:08:09,139 hydrogen bonds so you have a donor and 183 00:08:15,490 --> 00:08:13,039 acceptor sorry all right I'm not a 184 00:08:19,390 --> 00:08:15,500 chemist Emma biochemist and then with 185 00:08:20,589 --> 00:08:19,400 the cytosine and guanine you get three 186 00:08:23,589 --> 00:08:20,599 interactions so it's a little bit 187 00:08:26,050 --> 00:08:23,599 stronger and then because these are 188 00:08:27,790 --> 00:08:26,060 really nice planar molecules they stack 189 00:08:30,279 --> 00:08:27,800 really nicely on top of each other and 190 00:08:32,469 --> 00:08:30,289 that's also what causes the twist of the 191 00:08:34,180 --> 00:08:32,479 helix is the way that though that the 192 00:08:36,699 --> 00:08:34,190 bases prefer to stack on top of each 193 00:08:37,779 --> 00:08:36,709 other so that's why we have this really 194 00:08:39,670 --> 00:08:37,789 nice structure where you've got the 195 00:08:41,680 --> 00:08:39,680 bases all stacked on top of each other 196 00:08:45,370 --> 00:08:41,690 and then along the outside here are the 197 00:08:47,470 --> 00:08:45,380 sugars and the phosphates but one of the 198 00:08:48,910 --> 00:08:47,480 big questions like said is why did we 199 00:08:52,030 --> 00:08:48,920 use these specific ones you're going to 200 00:08:54,250 --> 00:08:52,040 hear about some maybe alternate nuclear 201 00:08:55,900 --> 00:08:54,260 bases later today so the ones that we 202 00:08:57,699 --> 00:08:55,910 actually use these are only the purines 203 00:08:59,310 --> 00:08:57,709 those larger ones the ones that we 204 00:09:03,180 --> 00:08:59,320 actually use are 205 00:09:05,580 --> 00:09:03,190 guanine but if you do like prebiotic 206 00:09:07,580 --> 00:09:05,590 chemistry in a lot of cases you can get 207 00:09:10,260 --> 00:09:07,590 many of these you know from stuff like 208 00:09:12,330 --> 00:09:10,270 form wide reactions or hcn 209 00:09:13,620 --> 00:09:12,340 polymerization that sort of thing you 210 00:09:15,330 --> 00:09:13,630 can get hypose anthing you can get 211 00:09:19,340 --> 00:09:15,340 xanthine so why did we end up with just 212 00:09:21,720 --> 00:09:19,350 these two rather than any of the rest 213 00:09:23,160 --> 00:09:21,730 similarly we can look at the amino acids 214 00:09:25,170 --> 00:09:23,170 which are what makes up all the proteins 215 00:09:27,870 --> 00:09:25,180 in our body for starters you can see 216 00:09:30,570 --> 00:09:27,880 there's obviously a lot more this might 217 00:09:33,360 --> 00:09:30,580 have to provide us with some hints as to 218 00:09:35,280 --> 00:09:33,370 why we use proteins for a lot of the 219 00:09:38,490 --> 00:09:35,290 business center our bodies now rather 220 00:09:40,650 --> 00:09:38,500 than nucleic acids because they're just 221 00:09:43,650 --> 00:09:40,660 a lot more chemically diverse so they 222 00:09:46,140 --> 00:09:43,660 can do more interesting chemistry so 223 00:09:47,820 --> 00:09:46,150 there's another question of which of 224 00:09:50,040 --> 00:09:47,830 these so I guess is kind of the inverse 225 00:09:54,780 --> 00:09:50,050 of the nucleobases you can't make all of 226 00:09:56,550 --> 00:09:54,790 these in prebiotic reactions so in that 227 00:10:00,090 --> 00:09:56,560 case why did we end up with some that 228 00:10:02,790 --> 00:10:00,100 are hard to make why did we there there 229 00:10:04,380 --> 00:10:02,800 are ones that you can make that didn't 230 00:10:06,240 --> 00:10:04,390 end up in life so why didn't we end up 231 00:10:07,260 --> 00:10:06,250 with those ones where they could have 232 00:10:08,850 --> 00:10:07,270 come from we said we've already had 233 00:10:13,130 --> 00:10:08,860 people have talked about you know 234 00:10:17,430 --> 00:10:13,140 stellar sources for amino acids and 235 00:10:21,720 --> 00:10:17,440 similarly to nucleic acids life only 236 00:10:25,680 --> 00:10:21,730 uses l-amino acids so the opposite kind 237 00:10:27,420 --> 00:10:25,690 of isomer so again a good question for 238 00:10:29,220 --> 00:10:27,430 that is why that came about 239 00:10:33,120 --> 00:10:29,230 unfortunately we don't have any of these 240 00:10:36,540 --> 00:10:33,130 I would love it if we did but I we'd all 241 00:10:38,010 --> 00:10:36,550 be out of jobs but because the laws of 242 00:10:39,210 --> 00:10:38,020 chemistry and the laws of physics have 243 00:10:41,130 --> 00:10:39,220 stayed the same over billions of years 244 00:10:44,460 --> 00:10:41,140 luckily we can extrapolate and say okay 245 00:10:46,140 --> 00:10:44,470 maybe we can sort of resurrect these 246 00:10:48,120 --> 00:10:46,150 processes that happen billions of years 247 00:10:51,450 --> 00:10:48,130 ago or at least some approximation of 248 00:10:52,890 --> 00:10:51,460 them and also we obviously need to know 249 00:10:54,360 --> 00:10:52,900 sort of what the environment was at the 250 00:10:55,830 --> 00:10:54,370 time so we can get a lot of information 251 00:10:57,210 --> 00:10:55,840 with that from the geologic record and 252 00:10:58,380 --> 00:10:57,220 I'm not going to talk about that this is 253 00:11:02,970 --> 00:10:58,390 not my specialty and you guys have heard 254 00:11:05,070 --> 00:11:02,980 about it for two days but a really brief 255 00:11:06,030 --> 00:11:05,080 history of sort of prebiotic chemistry 256 00:11:08,940 --> 00:11:06,040 and some of the really iconic 257 00:11:11,940 --> 00:11:08,950 experiments in it I could give you an 258 00:11:12,840 --> 00:11:11,950 hour-long talk just on interesting crew 259 00:11:15,780 --> 00:11:12,850 biochemistry 260 00:11:17,340 --> 00:11:15,790 but this sort of gives you a historical 261 00:11:19,319 --> 00:11:17,350 overview as well so this guy named glob 262 00:11:21,720 --> 00:11:19,329 way back in nineteen thirteen made 263 00:11:23,610 --> 00:11:21,730 glycine which you've heard talked about 264 00:11:25,410 --> 00:11:23,620 it's the simplest amino acid so it's 265 00:11:27,360 --> 00:11:25,420 pretty easy to make and the grand scheme 266 00:11:29,879 --> 00:11:27,370 of things so that's why you could do it 267 00:11:32,999 --> 00:11:29,889 a hundred years ago so all he did was 268 00:11:34,110 --> 00:11:33,009 pass a electric discharge simulating 269 00:11:36,509 --> 00:11:34,120 maybe lightning or something like that 270 00:11:38,430 --> 00:11:36,519 through carbon dioxide ammonia and water 271 00:11:39,960 --> 00:11:38,440 vapor so really simple chemicals that 272 00:11:43,680 --> 00:11:39,970 give you a building block of life when 273 00:11:45,809 --> 00:11:43,690 you add energy to them this guy named Bo 274 00:11:49,199 --> 00:11:45,819 dish made uracil which is one of the 275 00:11:51,960 --> 00:11:49,209 bases that's found in RNA and in that 276 00:11:55,040 --> 00:11:51,970 case it was just URI again really simple 277 00:11:58,650 --> 00:11:55,050 compounds malic acid is a very small 278 00:12:00,780 --> 00:11:58,660 very small acid with sulfuric acid which 279 00:12:03,230 --> 00:12:00,790 some people believe would would have 280 00:12:05,730 --> 00:12:03,240 been around in prebiotic times as well 281 00:12:07,650 --> 00:12:05,740 open and halt dein were two theorists 282 00:12:11,360 --> 00:12:07,660 that came up with a lot of the sort of 283 00:12:13,829 --> 00:12:11,370 general theoretical framework of the 284 00:12:16,740 --> 00:12:13,839 conditions on early Earth and how those 285 00:12:17,970 --> 00:12:16,750 could have led to life and then Stanley 286 00:12:20,460 --> 00:12:17,980 Miller you guys heard about yesterday 287 00:12:23,220 --> 00:12:20,470 who's responsible for the probably the 288 00:12:26,189 --> 00:12:23,230 most iconic prebiotic chemistry reaction 289 00:12:29,490 --> 00:12:26,199 in which you're simulating volcanic 290 00:12:31,350 --> 00:12:29,500 lightning in a in an atmosphere and 291 00:12:33,829 --> 00:12:31,360 again really simple compounds that give 292 00:12:36,629 --> 00:12:33,839 you a bunch of different amino acids 293 00:12:40,170 --> 00:12:36,639 it's in some cases ones that are in life 294 00:12:42,569 --> 00:12:40,180 in some cases ones that aren't this is 295 00:12:44,790 --> 00:12:42,579 my view of prebiotic chemistry provided 296 00:12:47,790 --> 00:12:44,800 chemistry's job is to get us from those 297 00:12:49,590 --> 00:12:47,800 really simple molecules that should have 298 00:12:50,910 --> 00:12:49,600 been available on early Earth to the 299 00:12:53,579 --> 00:12:50,920 building blocks of life and then 300 00:12:56,160 --> 00:12:53,589 ultimately to long-chain polymers that 301 00:12:57,689 --> 00:12:56,170 we not necessarily of the lengths that 302 00:13:00,290 --> 00:12:57,699 we have today but long enough that they 303 00:13:04,319 --> 00:13:00,300 can actually do interesting things 304 00:13:05,879 --> 00:13:04,329 without so I guess if you really want to 305 00:13:06,809 --> 00:13:05,889 get into sort of definitions of life you 306 00:13:10,470 --> 00:13:06,819 could say that you're going you know 307 00:13:12,240 --> 00:13:10,480 from abiotic to a more biotic synthesis 308 00:13:13,949 --> 00:13:12,250 of interesting molecules and stuff like 309 00:13:15,329 --> 00:13:13,959 that when you have some of these longer 310 00:13:16,800 --> 00:13:15,339 chain polymers I'm not saying they need 311 00:13:19,620 --> 00:13:16,810 to look exactly like what we have today 312 00:13:21,750 --> 00:13:19,630 because for various reasons some of 313 00:13:23,759 --> 00:13:21,760 those components aren't necessarily 314 00:13:25,229 --> 00:13:23,769 perfect 315 00:13:26,910 --> 00:13:25,239 of energetics in terms of stability 316 00:13:28,769 --> 00:13:26,920 stuff like that but if we get to 317 00:13:31,040 --> 00:13:28,779 something look similar then i would say 318 00:13:33,720 --> 00:13:31,050 prebiotic chemistry he's done this job 319 00:13:35,249 --> 00:13:33,730 another thing that could help prebiotic 320 00:13:37,290 --> 00:13:35,259 chemistry do this job once you've got 321 00:13:41,009 --> 00:13:37,300 some of the more complex molecules 322 00:13:42,389 --> 00:13:41,019 there's this idea called self assembly 323 00:13:44,249 --> 00:13:42,399 which is exactly what it sounds like you 324 00:13:46,739 --> 00:13:44,259 put these molecules together and then 325 00:13:48,989 --> 00:13:46,749 they self-assemble into long long 326 00:13:51,239 --> 00:13:48,999 structures the long complex structures 327 00:13:54,949 --> 00:13:51,249 this is kind of a way that you might be 328 00:13:57,780 --> 00:13:54,959 able to make a big stuff that looks like 329 00:14:00,210 --> 00:13:57,790 RNA or DNA or proteins today but without 330 00:14:02,789 --> 00:14:00,220 having them actually covalently bound to 331 00:14:05,249 --> 00:14:02,799 each other so in this case these are I 332 00:14:07,979 --> 00:14:05,259 mean these do kind of look like purines 333 00:14:09,840 --> 00:14:07,989 in the middle here and these assemble 334 00:14:11,699 --> 00:14:09,850 mostly based on just the stacking 335 00:14:13,829 --> 00:14:11,709 interactions of these surfaces so again 336 00:14:15,239 --> 00:14:13,839 they're nice like flat molecules and 337 00:14:16,619 --> 00:14:15,249 they can just stack on top of each other 338 00:14:18,689 --> 00:14:16,629 over and over and over until you get 339 00:14:22,280 --> 00:14:18,699 these really huge long complexes that 340 00:14:24,900 --> 00:14:22,290 you can see with like light microscopes 341 00:14:28,889 --> 00:14:24,910 so once you've got long-chain polymers 342 00:14:30,600 --> 00:14:28,899 you get into hypotheses about what came 343 00:14:33,019 --> 00:14:30,610 first which is sort of a chicken the egg 344 00:14:35,759 --> 00:14:33,029 idea there are people that believe that 345 00:14:37,379 --> 00:14:35,769 RNA came first and I'm of that school 346 00:14:40,799 --> 00:14:37,389 because that's where I do my research in 347 00:14:42,689 --> 00:14:40,809 but and luckily we don't have I don't 348 00:14:45,359 --> 00:14:42,699 think any we might have a couple people 349 00:14:47,220 --> 00:14:45,369 that might disagree with me but there's 350 00:14:50,639 --> 00:14:47,230 also the idea that proteins came first 351 00:14:52,530 --> 00:14:50,649 or the metabolism came first but I'm the 352 00:14:55,169 --> 00:14:52,540 majority of the talks that you guys are 353 00:14:56,910 --> 00:14:55,179 going to hear about this sort of we have 354 00:14:59,039 --> 00:14:56,920 some polymers but not really complex 355 00:15:00,929 --> 00:14:59,049 life are going to deal with the RNA 356 00:15:02,549 --> 00:15:00,939 world so the RNA world hypothesis states 357 00:15:06,210 --> 00:15:02,559 that early in evolution again we're 358 00:15:08,249 --> 00:15:06,220 still talking well before Luca RNA 359 00:15:10,350 --> 00:15:08,259 served both informational and functional 360 00:15:14,789 --> 00:15:10,360 roles so it carried the information even 361 00:15:17,699 --> 00:15:14,799 though it's not as stable as DNA is and 362 00:15:20,059 --> 00:15:17,709 it also carried out more functional the 363 00:15:23,489 --> 00:15:20,069 functional roles in terms of like making 364 00:15:25,379 --> 00:15:23,499 amino acids or making themselves making 365 00:15:29,609 --> 00:15:25,389 you know making nucleobases that sort of 366 00:15:32,699 --> 00:15:29,619 thing so eventually DNA replaced the 367 00:15:34,409 --> 00:15:32,709 archival informational role of RNA again 368 00:15:36,980 --> 00:15:34,419 unless your virus but I don't have to 369 00:15:38,570 --> 00:15:36,990 talk about viruses today 370 00:15:39,889 --> 00:15:38,580 so because DNA is a little bit more 371 00:15:41,690 --> 00:15:39,899 stable so it's better for a long-term 372 00:15:45,170 --> 00:15:41,700 storage think of it as your heart your 373 00:15:46,670 --> 00:15:45,180 body's hard drive rather and protein 374 00:15:48,019 --> 00:15:46,680 like I said before because the amino 375 00:15:51,440 --> 00:15:48,029 acids the building blocks are more 376 00:15:53,630 --> 00:15:51,450 chemically varied that ended up 377 00:15:55,490 --> 00:15:53,640 replacing a lot of the functional roles 378 00:15:56,990 --> 00:15:55,500 of RNA because you can do more interest 379 00:16:00,260 --> 00:15:57,000 in chemistry with proteins than in most 380 00:16:02,630 --> 00:16:00,270 cases you can do with RNA but RNA still 381 00:16:06,139 --> 00:16:02,640 serves both the these purposes today so 382 00:16:09,230 --> 00:16:06,149 that's the real sort of linchpin to the 383 00:16:11,300 --> 00:16:09,240 RNA world is that there's RNA still 384 00:16:14,840 --> 00:16:11,310 carries information from one place to 385 00:16:16,850 --> 00:16:14,850 another in the cell in all life on earth 386 00:16:24,079 --> 00:16:16,860 it serves as the short-term memory or 387 00:16:26,030 --> 00:16:24,089 the RAM of life and the the ribosome 388 00:16:27,470 --> 00:16:26,040 which is what makes all of life on earth 389 00:16:29,840 --> 00:16:27,480 so again that's sort of a 390 00:16:32,360 --> 00:16:29,850 chicken-and-egg conundrum you have the 391 00:16:36,579 --> 00:16:32,370 ribosomes functional parts are mostly 392 00:16:40,010 --> 00:16:36,589 made of RNA so with that you can't have 393 00:16:41,810 --> 00:16:40,020 you can't have protein without the thing 394 00:16:43,550 --> 00:16:41,820 that makes protein which is made of RNA 395 00:16:45,500 --> 00:16:43,560 so again another pretty good piece of 396 00:16:47,990 --> 00:16:45,510 evidence that RNA probably came first 397 00:16:49,699 --> 00:16:48,000 and then ribozymes which are responsible 398 00:16:52,040 --> 00:16:49,709 for a lot of gene regulation stuff like 399 00:16:54,949 --> 00:16:52,050 that are basically exactly what they 400 00:16:56,360 --> 00:16:54,959 sound like they're RNA enzymes and 401 00:17:00,290 --> 00:16:56,370 there's tons of those left over in life 402 00:17:02,000 --> 00:17:00,300 today to wait at that time all right all 403 00:17:04,429 --> 00:17:02,010 right so let's get back to this central 404 00:17:07,910 --> 00:17:04,439 dogma I'm not going to talk about this 405 00:17:10,809 --> 00:17:07,920 trend this transition going from DNA to 406 00:17:14,240 --> 00:17:10,819 RNA but it's called transcription it's 407 00:17:16,100 --> 00:17:14,250 performed mostly by protein enzymes but 408 00:17:18,770 --> 00:17:16,110 I am going to talk about translation 409 00:17:21,020 --> 00:17:18,780 which is exactly what it sounds like 410 00:17:23,809 --> 00:17:21,030 it's translating the genetic code into 411 00:17:25,370 --> 00:17:23,819 functional proteins so what is 412 00:17:28,640 --> 00:17:25,380 responsible for that because I just said 413 00:17:33,200 --> 00:17:28,650 is the ribosome it reads the messenger 414 00:17:34,610 --> 00:17:33,210 RNA and turns it into through the these 415 00:17:36,950 --> 00:17:34,620 other functional RNAs which are called 416 00:17:38,750 --> 00:17:36,960 transfer RNAs which carry the amino 417 00:17:42,860 --> 00:17:38,760 acids the building blocks of proteins to 418 00:17:46,820 --> 00:17:42,870 the ribosome they make in a coated and 419 00:17:50,380 --> 00:17:46,830 sort of logical way this peptide chain 420 00:17:57,470 --> 00:17:53,590 so I need to say about that for it now I 421 00:18:00,140 --> 00:17:57,480 have grossly oversimplified things for 422 00:18:02,810 --> 00:18:00,150 the purposes of time this is actually a 423 00:18:04,310 --> 00:18:02,820 little bit more in-depth what the sort 424 00:18:05,900 --> 00:18:04,320 of informational network of life looks 425 00:18:07,669 --> 00:18:05,910 like what I'm not going to give in to it 426 00:18:10,909 --> 00:18:07,679 we again we can talk heard it later if 427 00:18:13,700 --> 00:18:10,919 you want yeah but essentially you need 428 00:18:15,980 --> 00:18:13,710 to know that DNA said so goes to 429 00:18:17,960 --> 00:18:15,990 functional and informational roles both 430 00:18:19,520 --> 00:18:17,970 of those interact with proteins and then 431 00:18:22,669 --> 00:18:19,530 these functional networks are stuff like 432 00:18:24,380 --> 00:18:22,679 metabolism which is grossly complex but 433 00:18:26,690 --> 00:18:24,390 people are still going to try and 434 00:18:31,669 --> 00:18:26,700 explain to you today and I do not envy 435 00:18:33,529 --> 00:18:31,679 them that so once you've got proteins in 436 00:18:36,440 --> 00:18:33,539 life proteins evolved in a very 437 00:18:39,919 --> 00:18:36,450 interesting way where it's not in a lot 438 00:18:42,110 --> 00:18:39,929 of cases it's not you know really small 439 00:18:44,960 --> 00:18:42,120 changes especially probably early in 440 00:18:46,430 --> 00:18:44,970 evolution they evolve in modular ways so 441 00:18:48,289 --> 00:18:46,440 rather than having just you know you 442 00:18:50,330 --> 00:18:48,299 change one building block here one 443 00:18:55,789 --> 00:18:50,340 building block there they're kind of 444 00:19:00,320 --> 00:18:55,799 like I can't really use Lego because 445 00:19:03,110 --> 00:19:00,330 that's building blocks but essentially 446 00:19:05,360 --> 00:19:03,120 big globular chunks of proteins that 447 00:19:08,210 --> 00:19:05,370 sort of interchange with each other to 448 00:19:10,490 --> 00:19:08,220 give you different functions and 449 00:19:11,750 --> 00:19:10,500 different proteins so proteins are 450 00:19:13,820 --> 00:19:11,760 really interesting in that they can 451 00:19:15,440 --> 00:19:13,830 combine functions so if you know there's 452 00:19:17,480 --> 00:19:15,450 two functions that are kind of related 453 00:19:18,950 --> 00:19:17,490 at some point in evolution a lot of 454 00:19:21,710 --> 00:19:18,960 cases they'll say hey let's get together 455 00:19:23,659 --> 00:19:21,720 and we'll do this as one protein rather 456 00:19:25,430 --> 00:19:23,669 than two so that's kind of what I'm 457 00:19:27,440 --> 00:19:25,440 getting at in terms of the modular 458 00:19:29,450 --> 00:19:27,450 structure protein evolution so in this 459 00:19:31,010 --> 00:19:29,460 case you can see this enzyme called gtp 460 00:19:35,480 --> 00:19:31,020 hydrolase on both of these by the way 461 00:19:37,100 --> 00:19:35,490 our ribosome affiliated proteins so you 462 00:19:38,659 --> 00:19:37,110 can see kind of the general structure 463 00:19:41,510 --> 00:19:38,669 this is just a cartoon diagram that 464 00:19:43,370 --> 00:19:41,520 shows you the not all of the side chains 465 00:19:45,710 --> 00:19:43,380 but just the backbone confirmations of 466 00:19:47,899 --> 00:19:45,720 the protein but you can see here that 467 00:19:50,390 --> 00:19:47,909 this looks really similar to this which 468 00:19:52,460 --> 00:19:50,400 is also found associated with the 469 00:19:55,520 --> 00:19:52,470 ribosomes so you have these hela seas 470 00:20:00,830 --> 00:19:55,530 here and it has you know its own 471 00:20:03,260 --> 00:20:00,840 separate domains as well yes so enzymes 472 00:20:06,020 --> 00:20:03,270 today carry out most of the 473 00:20:09,080 --> 00:20:06,030 complex chemistry in the body through 474 00:20:11,450 --> 00:20:09,090 mechanisms like this where I'm not an 475 00:20:13,270 --> 00:20:11,460 organic chemist either but you know 476 00:20:20,050 --> 00:20:13,280 you're you're shuttling electrons around 477 00:20:22,370 --> 00:20:20,060 and yes so that is this is just one of 478 00:20:24,410 --> 00:20:22,380 millions and millions and millions of 479 00:20:26,660 --> 00:20:24,420 proteins that are active in life today 480 00:20:32,000 --> 00:20:26,670 in a network that looks something like 481 00:20:33,530 --> 00:20:32,010 this and again really complex not going 482 00:20:34,760 --> 00:20:33,540 to try and go into it too much but there 483 00:20:36,650 --> 00:20:34,770 is somebody today that's going to try 484 00:20:38,630 --> 00:20:36,660 and go into this part of it at least so 485 00:20:42,190 --> 00:20:38,640 this is amino acid amino acid 486 00:20:45,920 --> 00:20:42,200 biosynthesis which like I said in 487 00:20:48,560 --> 00:20:45,930 previous we probably had to do this 488 00:20:50,840 --> 00:20:48,570 abiotic lee but today we have you know 489 00:20:52,610 --> 00:20:50,850 tons of proteins that actually take over 490 00:20:57,260 --> 00:20:52,620 on this and make all the amino acids 491 00:20:59,480 --> 00:20:57,270 that put together life today at some 492 00:21:01,670 --> 00:20:59,490 point in all of this process pre Luca 493 00:21:04,730 --> 00:21:01,680 I'm not going to try and say when you 494 00:21:07,670 --> 00:21:04,740 had to have an event where the all these 495 00:21:10,520 --> 00:21:07,680 processes become compartmentalised so 496 00:21:11,930 --> 00:21:10,530 that it's basically when interesting 497 00:21:13,280 --> 00:21:11,940 things are happening you don't want them 498 00:21:15,230 --> 00:21:13,290 to float away you want them to stay 499 00:21:16,970 --> 00:21:15,240 nearby so that they can do more 500 00:21:20,870 --> 00:21:16,980 interesting things and stay near the 501 00:21:23,720 --> 00:21:20,880 other interesting molecules so this is 502 00:21:27,110 --> 00:21:23,730 just a simple vision of what's called a 503 00:21:29,600 --> 00:21:27,120 protocell which is a version of cell 504 00:21:32,690 --> 00:21:29,610 that is just really basic and that it 505 00:21:36,980 --> 00:21:32,700 only has like some really essential like 506 00:21:39,920 --> 00:21:36,990 replication and a few metabolic 507 00:21:41,690 --> 00:21:39,930 functions so yes so you can see just 508 00:21:43,310 --> 00:21:41,700 little tiny pieces of RNA in here that 509 00:21:44,900 --> 00:21:43,320 are encapsulated by like a lipid 510 00:21:47,900 --> 00:21:44,910 membrane pretty similar to what we have 511 00:21:50,090 --> 00:21:47,910 today so that's another thing that is 512 00:21:51,560 --> 00:21:50,100 pretty widely accepted to have happened 513 00:21:54,380 --> 00:21:51,570 before the last Universal common 514 00:21:58,970 --> 00:21:54,390 ancestor I think I'm getting to the end 515 00:22:00,470 --> 00:21:58,980 yes so in our history of evolution this 516 00:22:03,320 --> 00:22:00,480 is basically what I've tried to drive 517 00:22:04,850 --> 00:22:03,330 home to you today that you know we had 518 00:22:06,490 --> 00:22:04,860 all these processes that got us up to 519 00:22:08,600 --> 00:22:06,500 the last unit Universal common ancestor 520 00:22:10,070 --> 00:22:08,610 people are going to help fill in those 521 00:22:12,020 --> 00:22:10,080 some of those gaps today in their talks 522 00:22:14,480 --> 00:22:12,030 but that it was cellular 523 00:22:16,310 --> 00:22:14,490 compartmentalised that it probably had a 524 00:22:17,220 --> 00:22:16,320 DNA genome because DNA is more stable 525 00:22:20,370 --> 00:22:17,230 than RNA 526 00:22:24,960 --> 00:22:20,380 and the processes that are involved in 527 00:22:26,909 --> 00:22:24,970 turning DNA into RNA are very old we can 528 00:22:29,400 --> 00:22:26,919 tell based on the sequences of the 529 00:22:31,110 --> 00:22:29,410 proteins that they're similar enough in 530 00:22:32,730 --> 00:22:31,120 all of life that they probably came 531 00:22:34,830 --> 00:22:32,740 before life started branching off from 532 00:22:37,350 --> 00:22:34,840 each other had a sophisticated 533 00:22:40,740 --> 00:22:37,360 translation system so again that to get 534 00:22:42,690 --> 00:22:40,750 from the RNA to the protein and had a 535 00:22:45,600 --> 00:22:42,700 lot of genes but nowhere near the number 536 00:22:48,270 --> 00:22:45,610 that we have today so in the takeaway 537 00:22:50,130 --> 00:22:48,280 for this morning I just want you guys to 538 00:22:52,740 --> 00:22:50,140 remember the central dogma modern modern 539 00:22:57,780 --> 00:22:52,750 molecular biology and it did not hold 540 00:23:01,380 --> 00:22:57,790 true necessarily for you know millions 541 00:23:04,650 --> 00:23:01,390 or hundreds of millions of years in pre 542 00:23:07,650 --> 00:23:04,660 Luca where you go from DNA to RNA to 543 00:23:09,510 --> 00:23:07,660 functional protein pre biochemistry 544 00:23:10,919 --> 00:23:09,520 who's shown the feasibility of many that 545 00:23:14,000 --> 00:23:10,929 you can make many of life's building 546 00:23:17,730 --> 00:23:14,010 blocks with really simple compounds in 547 00:23:20,909 --> 00:23:17,740 earlier various different agreed-upon 548 00:23:22,830 --> 00:23:20,919 early earth conditions protein enzymes 549 00:23:24,510 --> 00:23:22,840 now fulfill most of the functional roles 550 00:23:26,070 --> 00:23:24,520 in life but RNA is still really 551 00:23:29,700 --> 00:23:26,080 important and that is kind of the idea 552 00:23:34,190 --> 00:23:29,710 of that RNA is a molecular fossil sort 553 00:23:37,320 --> 00:23:34,200 of left over from the RNA world and that 554 00:23:39,780 --> 00:23:37,330 the very in a pretty simple way the 555 00:23:41,430 --> 00:23:39,790 processes of that are common to all of 556 00:23:43,380 --> 00:23:41,440 life on earth were well established at 557 00:23:45,810 --> 00:23:43,390 the time of the last Universal common 558 00:23:51,510 --> 00:23:45,820 ancestor with that I will happily take 559 00:24:13,600 --> 00:24:10,630 wow I'm thirsty nothing okay Elena um 560 00:24:16,600 --> 00:24:13,610 mainly because of the the similarity of 561 00:24:18,460 --> 00:24:16,610 all life on earth there's so much so 562 00:24:20,350 --> 00:24:18,470 many genes that have really similar 563 00:24:21,460 --> 00:24:20,360 sequences that just the probabilities 564 00:24:23,940 --> 00:24:21,470 that they proud that they would have 565 00:24:26,470 --> 00:24:23,950 independently arose are just so small 566 00:24:27,820 --> 00:24:26,480 and not only in terms of sequences but 567 00:24:29,620 --> 00:24:27,830 in terms of structures so if you take 568 00:24:31,740 --> 00:24:29,630 the ribosome in particular and i'm using 569 00:24:35,020 --> 00:24:31,750 this solely because it's what I work on 570 00:24:43,120 --> 00:24:35,030 there are parts structurally if you 571 00:24:45,730 --> 00:24:43,130 overlay if you overlay the 3d structure 572 00:24:47,289 --> 00:24:45,740 molecular structure of an RKO ribosome 573 00:24:50,080 --> 00:24:47,299 with a bacterial ribosome there are 574 00:24:52,030 --> 00:24:50,090 parts of the core that are that have 575 00:24:53,560 --> 00:24:52,040 moved fractions of an angstrom in 576 00:24:55,390 --> 00:24:53,570 billions and billions of years of 577 00:24:56,890 --> 00:24:55,400 evolution so I'd say that's pretty good 578 00:24:59,770 --> 00:24:56,900 evidence that at some point they came 579 00:25:02,919 --> 00:24:59,780 from the same place that being said like 580 00:25:06,159 --> 00:25:02,929 said Luca is not one organism it's you 581 00:25:08,770 --> 00:25:06,169 know a bunch of communal organisms kind 582 00:25:10,299 --> 00:25:08,780 of living in a very hippie commune way 583 00:25:13,180 --> 00:25:10,309 where they're all sharing stuff back and 584 00:25:16,180 --> 00:25:13,190 forth you know so that they get to the 585 00:25:19,570 --> 00:25:16,190 point where at some point something gets 586 00:25:23,140 --> 00:25:19,580 a bit yeah so and then at some point 587 00:25:24,370 --> 00:25:23,150 some opportunist says I'm going off on 588 00:25:26,669 --> 00:25:24,380 my own and that's when you start getting 589 00:25:42,289 --> 00:25:26,679 these branches in the tree of life 590 00:25:55,019 --> 00:25:53,399 so oh so the question is if we did find 591 00:25:57,659 --> 00:25:55,029 life somewhere else on earth that just 592 00:26:00,960 --> 00:25:57,669 happened to have ribosomes and if they 593 00:26:03,810 --> 00:26:00,970 looked very similar to the ribosomes 594 00:26:05,580 --> 00:26:03,820 that we have on earth does that say that 595 00:26:08,460 --> 00:26:05,590 the ribosomes on earth might have 596 00:26:17,220 --> 00:26:08,470 independently originated rather than I 597 00:26:20,070 --> 00:26:17,230 guess that is an excellent question i 598 00:26:21,810 --> 00:26:20,080 mean there's there's multiple people 599 00:26:24,779 --> 00:26:21,820 right now that are trying to well 600 00:26:31,979 --> 00:26:24,789 actually yes so there's somebody that 601 00:26:34,369 --> 00:26:31,989 has made a very simple ribose RNA based 602 00:26:36,299 --> 00:26:34,379 system that is capable of transferring 603 00:26:39,060 --> 00:26:36,309 making peptide bonds which is 604 00:26:41,909 --> 00:26:39,070 essentially the job of the ribosome it's 605 00:26:44,070 --> 00:26:41,919 only about nine nucleotides really small 606 00:26:47,940 --> 00:26:44,080 with that case it was selected 607 00:26:50,279 --> 00:26:47,950 artificially in a lab so yeah I think 608 00:26:55,320 --> 00:26:50,289 it's entirely possible that there could 609 00:26:57,210 --> 00:26:55,330 be another kind of ribosome I would I'm 610 00:26:59,279 --> 00:26:57,220 skeptical i would say that if we found 611 00:27:02,129 --> 00:26:59,289 ribosomes that look really like the ones 612 00:27:04,499 --> 00:27:02,139 on earth i think that a ribosome could 613 00:27:06,869 --> 00:27:04,509 would probably independently arise 614 00:27:09,529 --> 00:27:06,879 somewhere else that was very different 615 00:27:12,029 --> 00:27:09,539 from what we have here i mean the the 616 00:27:15,269 --> 00:27:12,039 structural space that RNA is able the 617 00:27:19,950 --> 00:27:15,279 sample is just so massive you know 618 00:27:22,799 --> 00:27:19,960 there's yeah there's just way too many 619 00:27:25,950 --> 00:27:22,809 different confirmations that could that 620 00:27:28,099 --> 00:27:25,960 could form and i I'm sure that there are 621 00:27:30,840 --> 00:27:28,109 dozens if not hundreds of other 622 00:27:32,220 --> 00:27:30,850 confirmations that could make ribosome 623 00:27:34,139 --> 00:27:32,230 so ribosome is really interesting in 624 00:27:36,119 --> 00:27:34,149 that the way that it works today it 625 00:27:39,869 --> 00:27:36,129 doesn't work like any other enzyme in 626 00:27:41,849 --> 00:27:39,879 life all it's an entropy entropy trap it 627 00:27:44,279 --> 00:27:41,859 puts things in the right place so that 628 00:27:48,450 --> 00:27:44,289 the bonds can form between the amino 629 00:27:49,950 --> 00:27:48,460 acids on those tRNAs it it's very I 630 00:27:51,190 --> 00:27:49,960 would say it's pretty arguable whether 631 00:27:53,820 --> 00:27:51,200 or not the 632 00:27:58,750 --> 00:27:53,830 a ribosome actually has any chemical 633 00:28:00,430 --> 00:27:58,760 impact in that bond formation so I mean 634 00:28:01,720 --> 00:28:00,440 I think it's entirely possible that you 635 00:28:04,990 --> 00:28:01,730 could make a similar sort of entropy 636 00:28:27,940 --> 00:28:05,000 cage out of maybe something that isn't 637 00:28:29,980 --> 00:28:27,950 even RNA yes anybody um it's a really 638 00:28:32,379 --> 00:28:29,990 tough question so the question is is 639 00:28:34,720 --> 00:28:32,389 there a big energetic or is there any 640 00:28:37,379 --> 00:28:34,730 energetic advantage between the 641 00:28:39,220 --> 00:28:37,389 different isomers that life is chosen 642 00:28:40,779 --> 00:28:39,230 some people would say yes some people 643 00:28:43,450 --> 00:28:40,789 would say no some people would say if 644 00:28:45,759 --> 00:28:43,460 you can get a tiny tiny enantiomeric 645 00:28:47,379 --> 00:28:45,769 excess of one in some probiotic reaction 646 00:28:49,960 --> 00:28:47,389 or something like that that would be 647 00:28:54,810 --> 00:28:49,970 enough to take hold in over millions or 648 00:28:57,549 --> 00:28:54,820 billions of years would you would get 649 00:28:59,620 --> 00:28:57,559 yeah you would get home homogenous 650 00:29:01,389 --> 00:28:59,630 isomer incorporation and that's not to 651 00:29:04,600 --> 00:29:01,399 say that early in life we didn't have 652 00:29:10,590 --> 00:29:04,610 proteins that were made up of D&L amino 653 00:29:14,430 --> 00:29:10,600 acids or yeah D&L ribose sugars or 654 00:29:16,539 --> 00:29:14,440 whatever sugars were originally in RNA 655 00:29:18,700 --> 00:29:16,549 but the problem with that is that they 656 00:29:21,460 --> 00:29:18,710 wouldn't fold as regularly and so 657 00:29:25,269 --> 00:29:21,470 there's a definite advantage at least in 658 00:29:32,960 --> 00:29:25,279 terms of overall structure to having won 659 00:29:45,500 --> 00:29:42,049 oh yeah I'd say evolution is well in 660 00:29:49,130 --> 00:29:45,510 place by the time of Luca selection yeah 661 00:29:51,740 --> 00:29:49,140 pressures for sure it might not be 662 00:29:55,640 --> 00:29:51,750 exactly how we recognize evolution today 663 00:29:58,039 --> 00:29:55,650 but there's the idea of one of the 664 00:29:59,570 --> 00:29:58,049 really sort of most simple things that 665 00:30:01,549 --> 00:29:59,580 you need to get in place to get from 666 00:30:04,610 --> 00:30:01,559 simple life to complex life are 667 00:30:07,250 --> 00:30:04,620 replicators so probably some small piece 668 00:30:08,360 --> 00:30:07,260 of RNA well I say small me fifty or 669 00:30:10,520 --> 00:30:08,370 hundred nucleotides or something like 670 00:30:13,789 --> 00:30:10,530 that that's capable of making more of 671 00:30:16,370 --> 00:30:13,799 itself that is a huge advantage in terms 672 00:30:19,850 --> 00:30:16,380 of evolution you know we talk about 673 00:30:21,590 --> 00:30:19,860 evolution in terms of like I can run one 674 00:30:24,020 --> 00:30:21,600 percent faster than this guy kind of 675 00:30:26,750 --> 00:30:24,030 thing that's like you know ten thousand 676 00:30:28,549 --> 00:30:26,760 percent better performance and something 677 00:30:31,789 --> 00:30:28,559 like that is going to stick around a lot 678 00:30:34,580 --> 00:30:31,799 longer and just it's really evolution in 679 00:30:36,230 --> 00:30:34,590 an early life comes down to persistence 680 00:30:38,330 --> 00:30:36,240 more than anything how long you can 681 00:30:40,940 --> 00:30:38,340 stick around and how much more you can 682 00:30:57,470 --> 00:30:40,950 make of yourself that's my point of view 683 00:30:57,480 --> 00:31:08,530 so I guess my question 684 00:31:15,640 --> 00:31:14,320 that is a very tough question um yeah 685 00:31:19,410 --> 00:31:15,650 one I don't think I have a really good 686 00:31:22,930 --> 00:31:19,420 answer for its yeah it's really tricky 687 00:31:26,200 --> 00:31:22,940 if anybody has anything feel free I'm 688 00:31:32,500 --> 00:31:26,210 biochemist I all I know is that that's 689 00:31:35,950 --> 00:31:32,510 what we have now oh sorry so the 690 00:31:40,780 --> 00:31:35,960 question was if we did find life on Mars 691 00:31:43,630 --> 00:31:40,790 or elsewhere that also has d sugars and 692 00:31:44,530 --> 00:31:43,640 l-amino acids if we if that would mean 693 00:31:46,150 --> 00:31:44,540 that we could say that life 694 00:31:50,020 --> 00:31:46,160 independently arose twice in the 695 00:32:07,020 --> 00:31:50,030 universe and yeah and I don't have a 696 00:32:07,030 --> 00:32:15,730 you 697 00:32:20,110 --> 00:32:17,890 and there is something to the fact that 698 00:32:22,000 --> 00:32:20,120 I mean the rules of chemistry are the 699 00:32:23,470 --> 00:32:22,010 same everywhere in the universe I mean 700 00:32:24,490 --> 00:32:23,480 there's different environmental factors 701 00:32:28,570 --> 00:32:24,500 and stuff like that you have to take 702 00:32:32,890 --> 00:32:28,580 into account but so it depends on how 703 00:32:35,140 --> 00:32:32,900 much of it is chemical in origin and how 704 00:32:37,870 --> 00:32:35,150 much of it is biotic in origin how much 705 00:32:39,850 --> 00:32:37,880 of it is life that took hold and said 706 00:32:42,820 --> 00:32:39,860 hey let's just use these ones and how 707 00:32:44,919 --> 00:32:42,830 much of it is you know a tendency to 708 00:33:43,320 --> 00:32:44,929 create a biotic ly more of one than the 709 00:33:47,830 --> 00:33:45,850 there are some people who think that 710 00:33:49,660 --> 00:33:47,840 stuff like stellar radiation and that 711 00:33:51,820 --> 00:33:49,670 sort of thing could influence one in the 712 00:33:58,330 --> 00:33:51,830 other but I mean that's again way out of 713 00:33:59,620 --> 00:33:58,340 my yeah yeah exactly yeah so there are 714 00:34:01,510 --> 00:33:59,630 some people that think that the 715 00:34:03,160 --> 00:34:01,520 polarization polarized light in the 716 00:34:08,409 --> 00:34:03,170 stellar radiation might be enough to 717 00:34:12,010 --> 00:34:08,419 cause small tiny excesses in one isomer 718 00:34:14,290 --> 00:34:12,020 or the other so in that case yeah then 719 00:34:16,780 --> 00:34:14,300 maybe if something like that holds true 720 00:34:18,220 --> 00:34:16,790 and those excesses are enough that life 721 00:34:23,919 --> 00:34:18,230 takes hold of it and takes it to 722 00:34:31,210 --> 00:34:23,929 completion then then yeah perhaps you 723 00:34:42,830 --> 00:34:39,680 me too that's why we need those 724 00:34:44,379 --> 00:34:42,840 tortoises all right everybody do one 725 00:35:06,170 --> 00:34:44,389 more question we gotta move on to jen's 726 00:35:11,940 --> 00:35:09,660 yeah well I'm end yeah exactly if 727 00:35:14,610 --> 00:35:11,950 there's one thing that is on the side of 728 00:35:16,680 --> 00:35:14,620 the formation of life it's time you know 729 00:35:19,110 --> 00:35:16,690 we have tons of time to get stuff done 730 00:35:21,690 --> 00:35:19,120 so you can make the slowest process in 731 00:35:24,390 --> 00:35:21,700 the lab ever and as long as it you know 732 00:35:26,490 --> 00:35:24,400 still happens on a millions of your time 733 00:35:31,320 --> 00:35:26,500 scale it's still feasible in terms of 734 00:35:33,960 --> 00:35:31,330 the origins of life I think we got to 735 00:35:36,660 --> 00:35:33,970 keep going cuz Jen also has about a half 736 00:35:38,160 --> 00:35:36,670 hour worth of warm-up talk to give if