DNA vs RNA - Differences in Form and Function | Stated Clearly

this animation comes with a study guide for viewers and slides for teachers links are down in the video description they did clearly presents [Applause] what is the difference between DNA and RNA in biology it's often said that form equals function or or accurately form allows for function the form of your front teeth for example allows them to function as food chopping tools while the form of your molars allows them to function as food smashing tools similar connections between Form and Function can be found all the way down to the level of molecules like DNA and RNA physical molecules with well-known atomic structure groups of atoms stuck together in a specific pattern we'll compare form in a moment but first it's worth a quick refresher on the contrasting functions of DNA and RNA in modern cells animal cells like our own today's video Builds on our previous animations what is DNA and how does it work and what is a chromosome a chain of DNA is made of a sequence of paired links there are four different types of DNA links a-c-t and G called nucleotides a gene is a long stretch of DNA a sequence of nucleotides that code for something the specific sequence of nucleotides is what's really important here usually a gene codes for a distinct protein or a group of proteins but in some cases a gene simply acts as a template for a functional chain of RNA long story short genes tell amino acids have to line up to form proteins proteins interact with other molecules to make living cells cells form tissues tissues make organs organs combine to make you and me DNA does not code for proteins directly instead it more or less just sits there safely guarded inside the nucleus or the centerpiece of your cells waiting for other molecules to make RNA copies of its DNA genes those RNA copies and by copy here I mean they share mostly the same nucleotide sequence as the stretch of DNA they were copied from those RNA copies are the things that can actually leave the nucleus or they either perform a function on their own or they will be read by ribosomes the protein building machines we learned about in earlier animations in these cases the RNA copy of the DNA Gene functions as a set of instructions telling the ribosome how to build a specific type of protein that protein is what then goes on to perform an active function in the cell you can imagine DNA genes as extremely valuable books in a library so valuable that the library staff refuses to let anyone check them out and instead they use the books to make photocopies and distribute those copies out into the world a chain of RNA in this analogy is like a photocopy from pages of a DNA book modern cells use DNA for long-term information storage RNA copies of DNA are what go out into the cell for active use so now let's compare their similarities and differences in form the first difference you might notice here is that RNA is normally single stranded whereas DNA normally exists as a double-stranded spiral I will untwist these here so they're easier to compare this difference in structure has nothing directly to do with the innate properties of RNA and DNA chains of RNA are single stranded because cells build RNA chains single stranded this allows RNA to easily interact with other molecules inside the cell our cells build DNA chains double-stranded which among other things enhances their stability remember DNA is carefully guarded inside the cell it's the information storage it's worth noting that some viruses actually use RNA instead of DNA for their information storage and in many cases their RNA is also double-stranded for stability if we zoom out we see a second obvious difference RNA chains are shorter than DNA chains but this also has little to do with rna's intrinsic properties it's mostly a consequence of how the cell uses RNA cells only make RNA copies of individual genes rather than entire chains of DNA fun side note even though DNA chains are longer there's roughly three times more RNA than DNA by weight because there are just so many RNA copies of DNA genes in use at any given moment RNA and DNA are both made of repeating units called nucleotides zooming in we more clearly see that nucleotides consist of three main parts there's a carbon nitrogen base labeled here with different colors and letters there is a backbone made of a special sugar called ribose and there is a phosphate Linker in real life nucleotides are more like what we're seeing here these are space filling Atomic models each orb represents an individual atom the phosphate Linker is identical in both RNA and DNA which is why I painted them the same color in the cartoon model the sugar backbones however are slightly different between RNA and DNA Can you spot the difference the difference is right here DNA is missing an oxygen hydrogen group an oh group this seemingly tiny difference has huge consequences it's so important in fact that this difference is reflected in the names of these molecules RNA stands for ribonucleic acid ribo because the backbone is a normal ribose sugar DNA stands for deoxyribou nucleic acid deoxy because it's ribose sugar has been deoxygenated one of its oxygen hydrogen groups has been ripped away and replaced with a single stable hydrogen atom so what's the big deal about that tiny oh group why does it matter well oh groups are highly reactive you could say that they're sticky this extra stickiness allows RNA to be easily pulled around through the cell by proteins and other molecules this is great but this extra maneuverability comes at a price that reactive oxygen hydrogen group makes RNA easier to break if a chain of RNA bends just right its oh groups can even cause RNA to react violently with itself bursting in two deoxyribose the modified sugar that DNA's backbone is made of is naturally less reactive and far more stable compared to RNA DNA is innately tough to make up for rna's Rowdy fragile nature cells constantly digest RNA chains and constantly rebuild RNA chains they use those stable DNA genes as templates for those new RNA chains RNA is fragile and disposable DNA is tough and repairable the last noteworthy difference between DNA and RNA is found in their nucleotide bases there are four types of RNA bases which scientists have labeled a c g and U adenine cytosine guanine and uracil three of those four are identical in DNA but DNA uses thymine instead of uracil the reasons we think cells evolve to use thymine for DNA instead of uracil are complicated but in short the lack of uracil in DNA helps cells detect common forms of DNA damage and repair that damage again cells treat RNA chains as disposable and replaceable they guard DNA chains and repair them when damage is found so to recap even though DNA and RNA are nearly identical there are several important and easy to remember differences chains of RNA are relatively short and often single stranded they are active all throughout the cell they're highly fragile they are digested and rebuilt by the cell when damaged they are used for active functions such as protein coating chains of DNA are far longer and usually double-stranded DNA is trapped inside the nucleus except for in bacteria and other organisms that don't have nuclei DNA is relatively stable DNA is carefully guarded by cells and then repaired when damaged finally DNA is used for information storage just like the shape of your front teeth make them better for chopping while the shape of your molars make them better for smashing the atomic structure of DNA makes it naturally more stable than RNA your cells have evolved to exploit and enhance these innate differences modern cells use these two types of molecules for very different functions the molecular structure of DNA was first worked out in 1953 the field of genetics has come a long way since then but plenty of mysteries still remain people interested in the origin of life and its chemistry scientists like Dr Anthony Poole are trying to understand how RNA and DNA first came about did the earliest cells on Earth use RNA both as the active molecules in the cell and for information storage similar to how some viruses use RNA today could a cell really function with RNA alone if so what were the evolutionary steps leading to the RNA DNA system that modern cells use these are just some of the Mysteries currently being worked on many more exist Mysteries that you dear viewer might someday help solve I am John Perry and that is RNA versus DNA stated clearly this animation was funded in part by viewers like you at patreon.com it was also funded in part by Tay Al madama the center for fundamental inquiry which is a research center at the faculty of science at the University of Auckland New Zealand comprises a transdisciplinary group of academics and students from physicists to philosophers they're interested in addressing big questions about the origin and evolution of life and the universe the Maori name of the center means first light or coming into Knowledge from Darkness it alludes to a stage in the Maori fakabapa their genealogy of the creation of the world as well as the first light a telescope sees when commissioned

Channel: Stated Clearly

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Length: 10min 50sec (650 seconds)

Published: Wed Jan 25 2023