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DNA Replication Explanation

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DNA but it's so much it is the ultimate director for sales and two codes for your traits it's a major component of what makes you you when you have a really Macho like DNA that is ultimately responsible for controlling the cell it would make sense that when you make another cell like in mitosis you would so have to get more DNA into that cell and that introduces our topic of DNA replication which means making more DNA first let's talk about where and when first where it occurs in the nucleus if the cell has a nucleus remember not all cells have a nucleus this video clip is actually going to focus on the types of cells that do have a nucleus there known as eukaryotes prokaryotes which are cells that do not have a nucleus they do things a little differently they also do DNA replication but that is not going to be Focus for this clip next when when does this happen happens during interphase when a cell is growing its carrying out cell processes and it's replicating its DNA you know what it's not doing it the exact same time writing you don't want to sell to be replicating DNA and biting at the same time that's a little bit too much multitasking so DNA replication does what happened during cell division their wise known as mitosis in fact cells replicate their DNA before division processes like My toe and meiosis because once you make the new cell you better have DNA to put in there I think DNA replication would actually make a great video it's actually quite exciting I'm going to introduce the key players in DNA replication so that you can get some background information not the majority of these keep players that I'm going to introduce are enzymes in biology when you see something end in ASE you might want to check as it's very possible maybe an enzyme enzymes have the ability to speed up reactions and build up or break down the items that they act on so here we go with Arc players first helicase this is the only thing enzyme if you recall it DNA has two strands you can think of helicase is unzipping two strands of DNA helicase doesn't have a hard time doing that DNA polymerase the Builder this enzyme replicates DNA molecules to actually the new strand of DNA primase the initializer with this grade of DNA polymerase is poor DNA polymerase can't figure out where to get started out something called a primer primase makes the primer so that DNA polymerase can figure out where to go to start to work you know it's kind of interesting about the primer makes it's actually a piece of RNA ligase the gluer it helps glue DNA fragments together how about why you would need that a little later I don't feel overwhelmed we'll go over this sequence in order please keep in mind that like all of our videos we 10 give the big picture but there is always more detail to every biological process we cover that's really true for DNA replication DNA patient starts at a certain part called the origin usually this part is identified by certain DNA sequences there can be multiple Origins within the DNA is the origin helicase the unzipping enzyme comes in and unwinds unzips the DNA SSB proteins what stands for single stranded binding proteins bind to the DNA strands and they keep them separated primase comes in and makes RNA primers on strength and that's really important because otherwise when DNA Bloomer ice comes in it it wouldn't know where to start now DNA polymerase can get to work remember it's the important enzyme that adds DNA bases you have two strands right there nautical remember they complement each other they also are antiparallel so that means they don't really go in the same direction with DNA we don't say a strand goes north South the directions for the DNA strands are little different we say that DNA either goes 5 Prime to 3 prime or 3 Prime two five crime this can seem very confusing what in the world does that mean well the sugar of DNA is part of the backbone of DNA it has carbon the carbons on the sugar are numbered right after the oxygen in a clockwise Direction One Prime to Prime 3 Prime for Prime and 5 Prime to 5 Prime carbon is actually outside of the Ring structure now you do the same sing for the other side but keep in mind this strand is flipped just because DNA strands are antiparallel to each other so let's count these again why is from the oxygen when Prime to Prime 3 Prime for Prime 5 Prime and the 5 Prime is out of the ring this strand on the runs 5 Prime to 3 Prime and the Strand on the right here runs 3 Prime to 5 Prime well it turns out that can only work in the 5 Prime to 3 Prime direction that runs 5 Prime to 3 Prime is fine it's called feeding strand but the other strand will make it a little tricky DNA polymerase can only go in the 5 Prime to 3 Prime Direction so primase it has to set a lot of extra primers down to do that is shown here it takes longer to this strand is called the strand which is pretty fitting on the lagging strand you tend to get these little fragments of synthesize DNA they're called okazaki amazing named the primers have to get replaced with DNA bases since the primers were made of RNA ligase that's the blooming enzyme as I like to nickname it has to take care of the gaps in the Oppa sake fragments know in the end you have two identical double helix DNA all kills from your one original double helix DNA molecule we call the semi conservative replication because the two copies each contain one old original Strand and one newly-made one oh one last thing surely you've had to proofread your work before play catch errors well you definitely don't want DNA polymerase to make an error if it makes the wrong DNA base then you could have an incorrectly coded which could ultimately end up in the incorrect protein or no protein is just awesome it has proofreading ability which means it rarely makes mistakes and that's a good thing that's it for the amoeba sisters and we remind you to stay curious

Uploaded by Adeline Tang Peralta.

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