this is part two of the biochemistry lecture now focusing a little bit more on process so in part one we really focused on defining the different types of biological molecules including the polymers and now we're going to talk a little bit more of a process connection between two of them and so we're going to zoom in a little bit just on the nucleic acids as well as protein and focus on the processes that conveys the information out of the dna stored in our nucleus into the protein which then does the work of the cell in the organism outside of the nucleus sometimes you may hear this process of gene expression or protein synthesis as the central dogma of biology and that really comes back to the idea that dna is the heritable component that is what's passed from one generation to the next showing the instructions of how to build proteins and ultimately build an organism and this process is what takes that information and gets it into the actual thing that is going to be living surviving reproducing and interacting with its environment so a good way to think about this is most of us are familiar with the term gene like you inherit you know something is in your genes and you get your genes from your parents um to be very explicit a gene is a portion of dna that codes for a particular protein and sometimes multiple proteins and we'll get to that in the very end of the class when we talk about control of gene expression so really the key pieces that we're looking at here are the polymers that i mentioned so we are going to go from the dna polymer converting that information into the rna polymer and then taking the information from the rna polymer and converting it into a protein and this takes two processes so the first one transcription is what we call the process that converts dna to rna and transcription is the name for the process that converts rna into protein and so we'll actually go through each of these components in detail looking at what enzymes do the work and how that information is actually conveyed so this is a common misconception and so i really want to make a strong point on this every single cell in an organism has the same dna okay so but they look very different right so up here we have some nerve cells oops sorry there's some nerve cells we have red and white blood cells these are some epithelial cells like cheek cells and then some sperm cells from humans and those all look vastly different even though they all contain the same dna and so the key to the diversity and variety that we see in cell types and ultimately in organism types as well comes back to not only the presence of the instructions from the dna perspective but also what part of the dna is being used to ultimately make proteins so in our nerve cells we're just making specific proteins that are used to convey those electrical messages and in your white blood cells you're making particular proteins that allow those cells to interact with foreign organisms that come into your body like bacteria or viruses and be able to identify and destroy those whereas things like your cheek cells their goal is to form a barrier and so they're going to be making the proteins that are able to do that and then of course sperm the goal is to travel and carry that dna forward to the next generation and so the key piece from this slide i want you to take home is that all the cells have the same dna but they look different because only some proteins are being made so not all cells make all possible proteins at all times and the analogy we're going to use here in just a second is your dna is kind of like an entire cookbook and so it wouldn't be likely that you're going to sit down and make every single thing in an entire cookbook at once you're going to make what's needed for the particular situation maybe you need an appetizer maybe you need a dessert it's the same way with your cells they're only going to make the proteins that they need based on their job even though they contain all of the dna all right so looking at that process again we are going to go from information stored long term in dna and convey that information into a temporary nucleic acid form which is rna and then we're going to use that temporary form out in the cytoplasm to build the protein which will then go and do whatever job is needed by the body i do want to point out that for most organisms this information flows in that particular direction right we don't see proteins going back to rna and we don't see rna going to dna i will say though there are some viruses that are an exception to this that their coded information is actually in rna and so when they go into another organism they have to go backwards and change their rna to dna and then go forwards with the process of making proteins so before we get into the full guts of this i want to just go ahead and play this video from the amoeba sisters this is it's kind of a fun um overall broad introduction to protein synthesis and then i will come back to you and we're going to talk through the really detailed specifics [Music] after learning about dna have you ever wondered how can the dna actually result in a trait let's take an example like eye color yes your dna has the genetic information that codes for the color of your eyes your eye color is based on a pigment that is inside the eyes but in order to have that pigment you have genes which are portions of dna that can code for proteins which help make that pigment so what we're going to talk about is how your dna can lead to the making of a protein this process is called protein synthesis synthesis essentially means to make something so protein synthesis means to make protein and you may wonder what's the big deal about proteins well you may not realize this but proteins are kind of a big deal they do all kinds of things proteins are involved in transport in structure in acting as enzymes that make all kinds of materials in protecting the body and so much more you've got to make proteins it's essential for you to live and what is so cool is that you are making proteins right now as you sit and watch this video it's happening in your cells they're making proteins so back to your dna and its role in all of this all of your cells have dna well a few exceptions and that dna is in the nucleus some dna is non-coding dna some dna makes up genes that are not activated more about that in our gene regulation video but we're going to talk about genes that are coding for active proteins so how are we going to get the information from these genes out of the nucleus so that the cell can start producing the proteins that it needs to make well let us introduce you to the amazing work of rna we have a video comparing and contrasting rna and dna we'll be brief here in saying that rna is a nucleic acid like dna but it has a few differences its role in protein synthesis also is huge before we get into the process please note our typical disclaimer we tend to simplify topics but as always we hope that you have the desire to explore this complex amazing process later on to learn all about the extra information that we don't have the ability to include in this short video in protein synthesis we can look at two major steps one is transcription and the other is translation transcription has a c in it and translation has an l in it i remember that c comes before l in the alphabet which helps me remember that transcription comes first i like a lot of alphabet mnemonics the transcription is when we're going to transcribe the dna into a message in your cells the dna is in the nucleus so therefore we're doing transcription in the nucleus in the step of transcription an enzyme called rna polymerase will connect complementary rna bases to the dna these rna bases are bonded together to form a single stranded mrna the m in mrna stands for messenger messenger rna consists of a message made of rna that has been based on the dna we do want to mention that this mrna is not usually ready to go right away there's usually a significant amount of mrna editing that occurs we highly encourage you to do some reading about that because it's not only fascinating it's critical for the process to work correctly so what's something great about being mrna well in eukaryotes you get out of the nucleus the mrna can go out of the nucleus into the cytoplasm where it's going to attach to a ribosome ribosomes make protein the ribosome is made of rrna and that's an easy one to remember because the r stands for ribosomal rna the ribosome is going to build our protein in the next step called translation you know you can find a lot of great clips and animations on translation that are just fantastic we're just going to break down some basics of what's happening in the cytoplasm if you look at this you have all these trna molecules available trna stands for transfer rna they carry an amino acid on them an amino acid is the monomer for a protein it's a building block for protein since we're making proteins we're going to need those amino acids to build it if you have a bunch of amino acids together you can build a protein so it's the trna that is going to bring those amino acids together to make that but wait how does the trna know which amino acids to bring that's why the mrna the message is so important because it's going to direct which trnas come in and therefore which amino acids are transferred all of these trnas are looking for complementary bases when they find the complementary bases on the mrna they transfer their amino acid when trna is bringing in the amino acids it reads the bases represented by these letters here on the mrna in threes so it doesn't read one letter at a time it reads in triplets that's called a codon so for example in this mrna the trna would read the codon aug one of these trnas contains a complementary anticodon which in this case is uac all trnas that have the anticodon uac will be carrying an amino acid called methionine a trna with the uac anticodon comes in to pair with the complementary aug codon on the mrna it transfers the amino acid it carries methionine the trna will eventually leave but it will leave behind its amino acid that's the first amino acid before looking at the next codon before we do the next codon to carry this on if you're wondering how did you know that the trna that went with the aug codon would be carrying an amino acid called methionine well for that you will find a codon chart helpful you can learn to use a codon chart to determine which amino acid each mrna codon will code for isn't it so fascinating that scientists have been able to determine which amino acid corresponds with these codons i used to have a codon chart poster and just marvel at that you could see on a codon chart that the aug codon on the mrna codes for methionine aug is also considered a start codon as methionine is typically going to be your first amino acid in proteins there are many types of amino acids in the codon chart but there are even more possible codon combinations that means there can be more than one codon that code for the same amino acid for example according to the mrna codon chart all of these mrna codons here code for the same amino acid leucine that means their complementary trnas all carry the same amino acid leucine okay so going back to the mrna let's try the next codon on this mrna cca on the codon chart you can see that codes for the amino acid proline the complementary trna has the anticodon ggu and look there's the proline that we knew it would be carrying the trna will transfer that amino acid and eventually leave where it can pick up another amino acid these amino acids are held together by a peptide bond and it will keep on growing typically at the very end of the mrna there is a stop codon stop codons do not code for an amino acid but when the ribosome reaches it it indicates that the protein building is finished so the result of translation is that you built a chain of amino acids that were brought in certain sequences based on the coding of the mrna but remember that mrna was complementary to the dna so the dna ultimately was the director of the entire protein building of course it couldn't have done it without some serious help from mrna rrna and trna protein folding and modification may occur and the protein may need to be transported this can all vary based on the protein structure and function another fascinating topic for another amoeba sisters video well that's it for the amoeba sisters and we remind you to stay curious [Music] all right so that's a great analogy um that they kind of talked about too you know looking at it from a perspective of the goal is to build that protein right protein synthesis and so the way that i like to remember this is thinking about your dna being all of the information present in your cell which is like your cookbook and the ultimate goal is the food that you're going to make which would be all those proteins that get built and of course in the middle of that is that mrna the messenger rna which is going to convey the message out of the nucleus out into the cytosol where it can meet up with the ribosome to do the work so we're going to kind of walk through both of those processes just looking at piece by piece how it works and then we'll have kind of put it all together at the end so i do want to step to the side here just for a second and mention that prokaryotes do this exact same process the only difference is that they do not have a nucleus and in the next unit we're going to talk quite a bit more about the cell and make those distinctions but because these guys like e coli like a bacteria don't have a nucleus they actually do their transcription and their translation in the same space and so that dna is the information is coded into mrna and then that mrna is used by the ribosome to ultimately build the protein so distinction here is that it does not come out of a nucleus because there's no nucleus and as we'll talk about with the eukaryotes here in just a second which are things that do have a nucleus there's actually a little bit of processing that occurs in the middle between transcription and translation and so we'll add that piece in as well that also does not occur in prokaryotes and so for these guys for the bacteria they do have the benefit of speed you can actually see in this image that the rna polymerase is making the mrna and ribosomes are actually attaching to it as it's being made and making proteins and so they do definitely have the advantage of speed but generally they have also the disadvantage of not being really judicious in their resource use you know do they need this many copies of these proteins um don't know but the premise would be just make what you need but when you're just a single cell organism you may have a little bit more flexibility in terms of access and or use of those resources okay so focusing on eukaryotes for the rest of the lecture again eukaryotes are things like plants animals and fungi they all have a nucleus and so for and us of course um so our dna is in the nucleus which means that mrna is built inside of the nucleus by copying the information present in the dna into rna nucleotides and then sending that rna out of the nucleus out into the rest of the cell where it can meet up with the ribosome and there you'll see that extra step that i mentioned in eukaryotes we have transcription then we have rna processing then we have translation and as was mentioned in the video one of the coolest things to be discovered was the idea that it isn't a one nucleotide to one amino acid it's almost like the nucleotides are the letters and when you put certain letters together it gives you a particular word and that word is the amino acid and so again when we're reading these letters i'm just making some letters up here for a second we are going to clump them in groups of three which we call a codon and each one of those codons is going to translate ultimately into a specific amino acid and keep in mind when we talked about our polymers in the last video the key is that proteins have a specific shape for function and that shape is determined by that r group that sticks out of the amino acid and so having the right amino acid is super critical for being able to have the right shape and therefore the right function so as we just talked about with the amoeba sisters you can look at all of the different codons and look at them in a chart so that you can figure out what amino acid goes with what codon and this actually is considered to be the genetic code for all life it doesn't matter if you're talking about a human or a giraffe or a pine tree or a little e coli they all use the same mechanism for converting dna to rna to protein and also use the same code from a molecular biology perspective this is what allows us to move instructions into different organisms through genetic engineering and you'll notice we have the start codon which is aug encodes for methionine and then we also have some stop codons up here that don't code for amino acids and instead they let the ribosome know that it has gotten to the end of the gene which just a reminder is the portion of the dna that codes for a specific protein all right so let's do a little bit of practice in terms of thinking about both of these processes by themselves so first let's look at transcription so again we've already said this multiple times but the goal of transcription is to take the information out of the dna and convey it instead into the messenger mrna which we abbreviate mrna this is done by the rna polymerase and this is actually a new ending so when something ends in a's that tells us that it's an enzyme and generally the remainder of the name tells us what it does and so if we have rna polymerase a's tells us it's an enzyme that's job is to make the rna polymer so sure enough this is a protein that is going to build rna by copying the information out of dna and if you think back to when we talked about the differences between dna and rna just a reminder that dna has a t c and g and when we get into rna we actually swap out t for u and so when we go through and line up our nucleotides with each other we have to remember that swap to the u so just showing you some pictures of what that looks like every single gene has a promoter the promoter is basically the start line and where the control of is this going to be made into a protein is going to occur and so the promoter is going to have some appropriate stimulation which we will talk about actually in unit 3 with genetics to say yes make the protein or no don't make the protein okay so of course since we're talking about protein synthesis we're going to go forward making the protein so our rna polymerase is going to bind to the promoter and it actually pries apart the dna double helix and then begins to align those rna nucleotides to match up with their corresponding dna nucleotides so we can zoom in on that a little bit and see that happening so this big guy now is our rna polymerase the blue is showing dna and then you can see those rna nucleotides being lined up with the corresponding base that they are able to bond with and just a reminder that a binds to t and dna but it's going to swap out that t for a u when we're switching between dna and rna g and c are easy because they always bind to each other so the rna polymerase will continue plugging along through the entirety of the gene and then once it reaches the end it will let the dna double helix go back together the rna polymerase will leave the dna and now we have our completed mrna transcript which is ready to go into the next step which is rna processing so let's do a little bit of practice i do want to point out for the purposes of this class we are not going to also include the idea of directionality remember that we talked about this when we learned about the nucleic acid polymers that they are directional meaning there's one right way to read them we are always going to just align our letters going from left to right and we're not going to necessarily try to adjust for the five prime to three prime right now the part that we're going to focus on is aligning the correct information and so i may give you a sequence like this and say given this sequence what would be the rna that would come from from it or even further i could give you a dna sequence and then say what protein would you get from this so but before we get our head of ourselves and get to the protein piece we have to first convert the dna to rna so step one when we're doing this type of practice is look at the sequence because what we need to know is is it dna or rna and just a reminder the way that we are going to determine that is dna has a t rna has a u so when we look at our sequence over here you can see there are t's present therefore we know its dna and it has to be converted to rna first before protein so i stuck in this little piece just so we have it here visually to remind us but we're basically going to go through and convert that message from dna into rna so c binds with g g t binds with a a binds with u okay so that's the key piece to remember right we had to swap out t for u so c with g again a with u t with a t with a c with g g with c g with c c with g g with c and c with g hey now we've made corresponding rna that matches up with our original dna okay and you'll notice with this lower sequence we changed out where we had if we look at our codons here right which is every three okay you'll notice that we ended up with a different letter swapped out into that codon right so instead of ggc up here we now have gtc which is the potential to give us a different amino acid and that's what we would consider to be a mutation we've slightly altered the instructions and that may also alter the outcome we'll have to look and see when we get to our protein to see if that's the case but let's go ahead and practice one more time converting this into rna so c to g t to a a to u okay all right so now we have our rna and you'll just want to give yourself some sequences and do some additional practice on that until you feel comfortable with it right so that leads us to our second step which is rna processing and this is when the original sequence of rna that's built has a few different things done to it to make it ready to go out and meet out with the ribosome there's actually three things that are done the first is the addition of a gtp cap and this is a form of energy that's going to help translation get started the second one is a poly a tail which is the addition of a whole bunch of a nucleotides on the end of the rna for protection and then the last piece is the removal of introns or actually which are actually chunks of sequence that are not needed to make the final protein the only pieces we need to keep for the protein we call exons so just looking at some pictures of what that looks like again our gtp cap you can see that here gives us some extra energy up at the front and that poly a tail which you can see over here is a bunch of extra a's so just in case another enzyme starts munching on this rna they're going to get into this stuff which is unimportant first and hopefully not get to the actual important part that will be used to make the protein now our third processing piece removal of the introns and so you'll notice here there are introns that are not going to be used to make the final protein so those get cut out and the remaining pieces get reattached interestingly the introns are a great place to look for mutations when we want to look at relationships because keep in mind that if you have a mutation in your intron it never makes it into the protein and so it's not going to cause you any issues and it's just going to be carried along in your dna so if you do some of those test kits like the 23 and me or something like that sometimes they're looking at mutations in your introns that have been carried on from the very first ancestor you had that had that mutation show up all right so now that we have cut our pieces that we don't need out we've put on our cap and our tail it is now ready for the mrna is ready to leave the nucleus and go out into the cytoplasm so this wheel is actually the one the type of genetic code you're going to see on your test as opposed to the square one we looked at earlier this one is just easier i think to read all you have to remember is start in the middle okay and so if the codon i give you is g c a you start in the middle and go g c a there's the amino acid we get okay so when you're practicing translation you're going to want to use this guy just so you have the right tools as you get ready for the test okay so as we saw earlier the process of translation has several players so of course the mrna contains the message the ribosome is going to do the work itself and then what it's going to use to actually take the information from nucleotides and link that to a corresponding amino acid is the trna and i have a picture a simplification simplified picture of that guy here and you can see there's that anti-codon that's going to line up with the corresponding codon down here in the mrna and then there is the amino acid on top so that it is able to convey the message correctly and specifically so that the protein gets built correctly okay so just a reminder with those terms so down here on the mrna this one is the codon that's what we look for in our wheel the anticodon is what is on the trna that's going to align with that and so if this is our t i'm sorry the t anti codon on the trna aligns with the codon on the mrna so we can see here that's our amino acid up top and we can see that the anticodon is aag and so then we can think about what that would line up with on the mrna and it would be u u c okay keep in mind this would not be t right we're not gonna go backwards we're going rna to rna now so mrna has the u in it anticodons which are part of the trna also have the u in it so just zooming in a little bit on the ribosome again it is a complex of protein and rna we heard in the video is referred to as ribosomal rna it does have a small subunit and a large subunit and so those two kind of come together like a hamburger bun on both sides of the mrna and then the trna connect with the corresponding sequence inside of the ribosome as they go ahead and build the protein itself so specifically as mentioned the methionine is the start amino acid that we always see therefore we have the start codon of aug that always codes for methionine so we always know that that is the beginning of our protein which can be really helpful from a molecular biology perspective when we're looking to see where the beginning of the gene is so that start codon is going to have this special initiator meaning getting it going trna that's going to bind then the large subunit of the ribosome is going to come over the top and latch on and now it's ready to get started so i'm just going to kind of talk you through what this looks like as we have each new trna come in with its anticodon and bind to the corresponding codon and then while it is in that position its amino acid is going to be connected to the building the growing amino acid chain which ultimately is going to become the protein so here we can see we have our trna that's present just label him with a little t there so remember he's trna and here's our protein growing with the various amino acids and so here's our next trna it's going to come in based on what this codon is right here okay so that codon is going to match the anticodon up here and when it comes in and latches on then the bond is able to be formed between the two amino acids and just a reminder we call that a peptide bond but it's done via dehydration synthesis that we already learned about so that h is taken off of one side and the oh off the other side then the bond is formed between the two amino acids and so now you can see the amino acid chain has grown and moved over and now this trna is lacking an amino acid so he's basically been used up in this case and so now the ribosome shifts which causes the empty one to get ejected and it opens up the slot for the next trna to come in and this process will just continue until the protein is fully built the way that the ribosome knows that it has reached the end of the protein instructions that are coded in that mrna is it's going to reach a stop codon so just a reminder there are these three particular codons that do not code for a trna and instead they bind to this other molecule which we call a release factor and that actually causes the entire assembly to come apart meaning the two parts of the ribosome separate the mrna comes out of there and the protein gets released and we have built a protein yay all right so let's get back to the practice piece so we did this earlier right and so now we're going to add in translation so if the question that you see on the test is given this sequence what would be the partial protein that would come from it because keep in mind a full gene is like 10 000 letters right so i'm not going to have you do that on an exam we're just going to do this partial piece so that you can practice so again remember that step one is determine is it dna or rna to start because if it's dna then we have to convert it to rna if it's already rna then we can skip ahead and go straight to the wheel okay so looking at our sequences over here again they are dna because we saw these before so reminder there's t's that are present therefore we know that it's dna so before we can go to our wheel let's go ahead and convert it to rna so again g c goes with g t goes with a a goes with u c goes with g etcetera okay and then we're gonna split that up into codons okay so into chunks of three and since this last one doesn't have any more we can't do an amino acid for that guy right we'd have to know all three so our first one is gga so we go again start in the middle we go g g a gives us gly so we're gonna write gly and then dash for our next one now we have u g u so we go u here let's erase for each one so that we can keep track of what we're doing here so u g u gives us cis then our next one we have a a g so a a g gives us lice and then our last one c c g we're going to go c c g gives us pro so the answer to that question would be looking for this answer glycis lys pro that is the protein that is built from that dna sequence okay so let's go ahead and do that next one you can practice it on your own i'm going to go ahead and just write it out because we want to see did the protein get changed when this nucleotide got changed in the dna so let's go ahead and determine that now okay and we split that up into our codons again so again gga gives us gly ugu gives us cis aag gives us lice and now c a g is it something different so we have c a g sure enough that one different nucleotide has now given us a different amino acid and it has the potential to now change the shape of the protein which we know shape equals function so this one change in the base of dna may have altered the function of our protein we'll have to see right this is what researchers do when they study dna and protein synthesis so again this is something you're going to want to practice you will have access to a wheel like this for your exam and so you can just use this right off the powerpoint slide to practice doing your own transcription from dna to rna and then translation from rna to protein all right so the last piece that we need to keep in mind and we talked about this again just on the last slide as well as in the last lecture that a protein has to have a specific shape for function and so reminder this is due to all of those r groups on the amino acids interacting with each other and if you don't remember what this piece is that i'm talking about go ahead and go back to the part one biochemistry lecture and re-watch the part on proteins where we go through how this folding happens because it's extremely important in proteins their 3d shape is what equals their function and of course as we already have talked about as well some proteins need to have additional pieces to work some actually need pieces cut off some need additional cofactors like vitamins or other nutrients or minerals like iron to be able to do their job and some of them are good to go as soon as they're built it really depends on the protein all right so with that let's just visually talk through our whole process again okay so we start up here at the top with transcription it's done by rna polymerase that is going to pry open the dna double helix shown in blue and it's going to build the corresponding rna transcript shown in red then our rna processing is going to add the cap and the tail and remove the introns then our mrna is fully ready to go it's able to leave the nucleus where it's going to meet up with the ribosome which is going to make use of trna and each individual trna has an amino acid on one side and an anticodon on the other side and the ribosome is going to move along that mrna molecule matching up the corresponding codon with its anticodon so that the protein is built accurately therefore it has the correct shape and then of course has the correct function as well this image is a really good one to just test yourself on if you kind of like black out all of the different labels and just see can you talk through the processes of transcription or translation or explain them to someone it's one of the best ways to know if you if you understand what is happening as well as what the differences are all right so with that i'm going to show you the bioflix video which is just another animation these are available in your canvas shell so you can always go back and re-watch them um just as kind of an overall summary of the processes we just talked about this student is cramming for her biology test with only a frosting covered doughnut for lunch specialized cells in her pancreas respond to the increasing amount of sugar in her blood by releasing insulin a small protein that regulates blood sugar levels let's go inside one of these cells to see how this protein is manufactured the instructions for making insulin are coded by a segment of dna in the nucleus in transcription an enzyme zips along the dna forming rna shown here in red rna nucleotides line up with their complementary dna partners transcribing the information in dna into rna as the rna grows it is processed in several ways first a modified guanine nucleotide is added to the beginning as a cap also segments of the rna strand that do not actually code for the protein are removed and the remaining segments of rna are reconnected finally extra adenine nucleotides are added to the end of the rna strand forming a tail the completed messenger rna mrna now leaves the nucleus the message in mrna is translated into a protein in the cytoplasm first a transfer rna trna arrives carrying a specific amino acid the small subunit of a ribosome attaches to the mrna now the large subunit of the ribosome attaches a second trna docks bringing another amino acid the ribosome helps to form a covalent bond between the two amino acids the mrna shifts and the first trna leaves a new trna brings another amino acid the ribosome helps to form a new bond and the process is repeated that one end of a trna molecule has a set of three bases called an anticodon that pairs with complementary bases on the mrna the other end of the trna carries a specific amino acid different types of trnas carry different amino acids in this way the message in mrna is translated into a specific sequence of amino acids for proteins that will be secreted from the cell like insulin the ribosome docks on the rough er and the protein grows into the er compartment the new protein molecules are packaged in a vesicle that is transported to the golgi apparatus where many proteins are processed however insulin is packaged in a vesicle that leaves the golgi and is then processed proteins secreted from the cell are shipped to the plasma membrane here insulin is secreted from the pancreas and begins to regulate the students rising blood sugar levels okay so that is it for us for biochemistry so back in part one we went through all of the different biological molecules including which ones make up polymers and what their corresponding monomers are then in this lecture we talked through protein synthesis which again is the process of transcription and translation and how we convey the genetic information stored in your dna to rna and then ultimately to proteins that do the work for you