the French biochemist and Nobel laurate Dr jacqu Mano famously said all that is true for eoli is true for the elephant and you might be thinking okay had Mano ever actually seen an elephant which is a totally fair question on the surface we see lots of differences between the Single Cell bacterium and the Elephant which contains upwards of a quadrillion cells but what Mano was actually getting at is that on a biochemical level all living things are actually shocking L similar we can see that Unity which comes from our shared evolutionary history in The Identical chemical building blocks that form the DNA and proteins of eoli elephants and well us despite our differences we can use many of the same chemical reactions to break down food harnessing energy along the way of course we need more energy than eoli needs and the Elephant needs more than us but the rules of the game are the same and across all forms of life that game is played with six key Elemental players now taking the field for team life carbon hydrogen nitrogen oxygen phosphorus and sulfur give it up for team schnaps hi I'm Dr Sammy your friendly neighborhood entomologist and this is Crash Course biology and this is some seriously banging theme music [Music] [Music] you're probably familiar with the periodic table as of 2023 it lists 118 known elements and it isn't unusual for it to be updated heck as recently as 2016 scientists added four new elements to it elements are just atoms by the way and they are pretty much the simplest form of stuff that exists an element is a name for a c certain type of atom when it comes to the team of life our Atomic Captain is carbon here on Earth carbon is the most common element in living things making it our MVP producers like plants and algae pull carbon dioxide from the air or water to make carbon-based molecules or connected groups of atoms when consumers like mice or Lizards or you eat your vegetables the molecules can be broken down then they get reused to build our own biolog molecules just like you might break down one Lego creation to build another these types of repeated uses are called biogeochemical cycles but carbon isn't just plentiful it takes a lot more to be MVP in The Game of Life One of carbon's most amazing talents is its ability to be bound up in larger molecules see to really pull together as a team to make life work our six elements need to make and break chemical bonds carbon wears number six on the periodic table and it's quite the team player it can form four lengths called coent bonds with other atoms think of calent bonds like the molecular version of a rodeo in this case carbon is the cowpoke lassoing bucking atoms hydrogen wears atomic number one on the periodic table it's the smallest element and it can only form one calent Bond so if we arrange four hydrogens around the carbon and connect them with lines to represent the bonds we've successfully built methane the simplest organic molecule so our chemical methane has both carbon and hydrogen which makes it an organic compound also known as an organic molecule forming an organic compound is one of the top moves in the team's Playbook because these compounds are the chemical basis for Life most components of food for example are made up of organic compounds including proteins carbohydrates and fats and we're not talking organic like the kind that you'd find on a food label at a grocery store that just refers to the lack of synthetic additives same name totally different thing but those labels can be wildly misleading so we're not going to get into that here no matter how they're built organic compounds will always include carbon in at least some capacity and the compounds change based on the number of players involved if we put four carbons in a row and connect them with calent bonds and then add in enough hydrogens to give each carbon four bonds bam we get butane which is helpful for all kinds of things including using a lighter to Kickstart your campfire organic compounds don't have to be straight chains of carbon atoms though if we rearrange butane we can make a branched organic compound called isobutane this compound is often used in gasoline butane and isobutane have the exact same chemical formula with four carbons and 10 hydrogens a piece this makes them isomers compounds with the same chemical formula but a different arrangement of atoms molecules can take all kinds of shapes and it can get pretty elaborate we all know that there is no IE in team and our MVP carbon often needs a little help from another member of the starting lineup wearing atomic number eight Here Comes oxygen oxygen is sort of like the team ball hog and doesn't collaborate as much with carbon it's only going to create two Cove valent bonds which can make team ups a little trickier take carbon dioxide for example it has the chemical formula CO2 so if carbon likes to make four bonds in oxygen too what do we do we run some special plays we put double calent b between carbon and each oxygen so the four bonds are shared between two other atoms score and now the moment you've all been waiting for give it up for the last member of our starting lineup with atomic number seven on its Jersey nitrogen it makes three bombs for example it teams up with three hydrogens to make ammonia we'll mention our second stringers phosphorus and sulfur a bit later they're they're also essential to our team our starting lineup can't win the game all on its own and winning the game in case you lost track means sustaining all life on Earth so these guys are kind of a big deal the upshot is that when our team coordinates their plays we get the four major classes of biological molecules that make up nearly everything in our bodies and not just our bodies elephant bodies plant bodies and every other living thing that you can think of so what are these Majestic molecules and how do they work like complicated Lego kits to build you and me the four types of biological molecules are lipids carbohydrates proteins and nucleic acids and they are made from our team schnaps and then they in turn make us lipids are organic molecules that can't dissolve in water like cooking oil or beeswax uh they're usually made of smaller blocks called fatty acids which consist of long chains of carbon atoms some lipids are chemical Messengers like the hormones estrogen and testosterone which help prepare our bodies for things like puberty and reproductive processes oh so that's what I had to blame for all those pimples thanks a lot lipids carbohydrates are our second class of biological molecules they're used as sweeteners and they are never ending at the Olive Garden meaning they're the main components of pasta and all of those endless bread sticks you might know them as carbs in our bodies carbs can be used to store energy for release as needed their mini Lego piece is a monosaccharide simple sugars like glucose or fructose stick a bunch of monosaccharides together and you get complex carbs like those in pasta and bread our brains are particularly hungry for glucose and they should be considering that the brain consumes 20% of the body's metabolic fuel our third type of biological molecule called nucleic acids store and transmit genetic information which is basically instructions that we inherit from our parents that tell our bodies how to work DNA stores this information and the nucleic acid RNA tells the body what to do with it all of this rests on the mini Lego piece called a nucleotide which is made of a simple carbohydrate a phosphate group and some nitrogen-rich rings did you see that phosphorus coming in for the assist we love a team player our fourth and final class are proteins like the hormone insulin that helps regulate our blood sugar or the antibodies that help our immune system F off infections some also have structural roles like the collagen that makes up much of our skin and while those proteins are tiny some huddle together so much that you can actually see them like the protein keratin that makes your hair and your fingernails proteins are built from amino acids and all amino acids are pretty similar but each one has its own special group that makes it unique like tryptophan the amino acid in that turkey leg that used to take the blame for making you tired even though your sleep hormones are made out of this stuff eating it doesn't mean you're going to get drowsy that turned out to be a myth the sleepiness was just because you were really full and finally taking the field we have S far it's in some of these amino acid building blocks giving us the s in schnaps as you can see these Atomic Lego pieces don't act alone they continue to build even bigger teams of molecules like say we need our bodies to interpret our DNA which we do need all the time the process is kind of like a text chain full of cated emojis DNA sends the messages that get interpreted by RNA a codebreaker extraordinaire these messages are not just your average gossip they're instructions for amino acids so the amino acids join together end to end making a polymer which is a large molecule containing many repeating molecules and the name for a molecule containing many other molecules by the way is a Macro Molecule DNA is the champion of polymerization or linking up repeating molecules to make macro molecules in humans chromosome 1 our largest chromosome contains a single polymer made of 498 million nucleotide blocks that's a lot of Legos it works out to over 16 billion atoms working together to store the genetic information in just one of our 46 chromosomes there are more atoms in that single chromosome of yours than there are humans on earth now that's a Macro Molecule we also have biological molecules to think for the sweeter things in life some carbohydrates can be made of just two Lego blocks like sucrose the carb that makes the fruit in your smoothie taste sweet or carbs can be macro molecules like polysaccharides which help plants and animals get their shape and store their energy let's check out how our bodies break down molecules it works the same way in polymers but for Simplicity we'll look at sucrose when you sip hot chocolate proteins in your digestive system break sucrose into the monosaccharide or simpler sugars glucose and fructose they do this by adding water to the calent bond holding them together these are called hydrolysis reactions with Hydro meaning water and Lis meaning to pull apart or loosen hydrolysis is a process that Cleaves one big molecule into two smaller molecules using water hydris lets us reuse the building block from the producers and the consumers that we eat to build up our own macro molecules each amino acid from a plant protein can be recycled to make the specific proteins that we need and the different proteins that organisms make contribute to the uniqueness among all living things so hydrolysis is how our bodies break bonds between building blocks but we also need to make new bonds putting the Lego pieces back together in new combinations for that there's the opposite of hydrolysis dehydration rate reactions just like the dehydration you might feel on a hot summer day this process involves water loss it removes water from the building blocks to make them stick together in chemical terms a water molecule is squeezed out from two building blocks joining them into a bigger molecule for example dehydration reactions occur when Three fatty acids Team Up by attaching to a molecule of glycerol a type of carbohydrate squeezing out water to make what's called a triglyceride this process helps Bears get ready for hibernation when their bodies live on fat stored during summer and fall life can take on a lot of different shapes but despite differences in the DNA code it's the same nucleotides carrying the message that makes every organism on this planet and the similarity doesn't stop there from a tiny amoeba to an enormous blue whale we'll see similar lipids holding stuff inside cells DNA and RNA working together to make proteins and structural proteins helping cells keep their shape and behind it all the six atom te team schops are key players in The Game of Life chemically speaking that is in the next episode we're going to take a deep dive into well water and how our friend H2O makes life better for everyone I'll see you then this series was produced in collaboration with hhmi biointeractive if you're an educator visit biointeractive.org g/c crashcourse for classroom resources and professional development related to the topics covered in this course thanks for watching this episode of Crash Course biology which was filmed at our studio here in Indianapolis Indiana and was made with the help of all of these nice people if you want to help keep crash course free for everyone forever you can join our team on [Music] patreon