 For the next series of mini lectures you'll be learning about DNA and you'll be knowing things about its structure and how it's inherited So what I hope that you will learn from these series of our mini lectures is I want you to know about what DNA is Why is it important? Where is it found and what makes it up and also how it gets copied? so First of all, what is DNA if you look at different sources, whether you're looking books are online Some people call DNA the chemical of life It's also called the molecule of inheritance and it can also be termed the molecule of life So there are different things that are different terminologies that are used to Describe DNA. What important thing is that we know that DNA is essential to life DNA is what makes us who we are basically whether you are there You're a human being to the lowest organism. We all Rely on this essential molecule now It's important to know that DNA is falling almost all organisms However, it's not found in some organisms some some organisms actually use RNA as their genetic material So just bear that in mind for our purposes. We're going to be focusing on DNA for this mini lecture So DNA as I said it contains information and the information it contains is in the form of genes and Genes basically are responsible for making us who we are genes at the definition I put here is that genes are actually functional units of DNA so they carry information for making proteins and They also are responsible for making RNA molecules So if this is an example of a series a stretch of DNA, so if you notice in the previous picture DNA is represented as a what we call a double helix and we'll talk a little bit about that later Now just bear in mind that this is also a double helix. It's just that I do it like this for simplicity purposes So let's us say this represents a long DNA molecule or genes would be Small units Along this DNA molecule. So this would represent a gene This one would represent a gene This one would represent a gene. So this is our DNA molecule. This is our gene gene one gene two and and gene three and This gene is going to have the information that makes this molecule, which is a protein. So this is actually Going to make this protein molecule. So that's one of the reasons why DNA is important one of the main major reasons the DNA actually makes protein DNA can also make functional RNA molecules and I'm just going to draw this picture to depict an RNA molecule and This molecule can form what are called functional RNA molecules. So this is actually a functional RNA molecule and These are molecules that work by themselves. They're not converted or they are not used to make proteins so we're going to talk about this later when we talk about gene expression so tRNA and transfer RNA and ribosomal RNA are actually called Functional RNA molecules So we say that genes are important because they make proteins So one of the major things that proteins do proteins are responsible for giving structure. So for example, this lady's here She actually has a protein called keratin and this is one of the proteins that are integrally important in Making here the texture that it is or the way it looks Also genes are important for making proteins like molecules like proteins are So this is an a protein called an enzyme and Enzymes are important in our body because they are Responsible for speeding up a lot of chemical reactions that occur that allows to exist as as human beings For example a major one. We need enzymes in order to convert energy into a usable form, which is ATP so this enzyme is making ATP or Converting energy to ATP which will allow this man to basically move So that is why we need DNA because of these Important functions that our body needs to undergo and in order to make us structurally how we are Then is very important extremely important in inheritance so in order for Information to be passed from parent to offspring. We need DNA to be duplicated. So it is important here Where we get our genetic material from both parents? So this is that you get half of your genetic information from dad Half of our genetic information from mom and this makes us who we are so in order for us as a species to continue We have to have a way to have this molecule passed down from one generation to the next so DNA without DNA basically we would cease to exist and this baby here Actually gets half his DNA from his mom half from that. So just remember that Where is DNA located? So the location of DNA depends on what they're dealing with a eukaryotic cell or a prokaryotic cell So in eukaryosis an important organelle called the nucleus Sorry about that So the nucleus is actually Where or genetic material DNA is found Whereas in prokaryote These organisms do not contain DNA. So therefore the DNA is found in the cytoplasm. It's not found in an organelle It's found in the cytoplasm in prokaryotes now if we were to look at a human being as an organism and This stickman represents that His so this is a human His body is made up of trillions of cells So if we were to zero in on just one of his cells This is a very crude representation of how a cell would look So I'm just highlighting the nucleus here. Of course, you have other organelles at our phone in a cell so this would be the nucleus of the eukaryotic organism we humans are eukaryotes and If we were to actually zoom in on the nucleus This blue area here that we see is actually representing Orgene material if we were to look at it close up or nucleus consists of 46 chromosomes so in humans we have 46 chromosomes and these are actually 23 pairs of chromosomes making 46 chromosomes and This makes up or genetic material which is our genome. So the genome is basically our 46 chromosomes Now if we were to take one of these chromosomes and zoom in on that each Chromosome actually is a DNA molecule. So this goes to our double helical structure, which is DNA So DNA is the component of our chromosomes which are found in the nuclei of our cells Now we think about DNA if DNA was allowed to stretch in a typical chromosome in a eukaryotic organism if this DNA from that chromosome was just allowed to be stretched out to make one lung fiber It would be about two meters long so from So from start to finish if you were to take into consideration the curves would make about two meters long but this DNA molecule has to fit into a nucleus of a cell which is 0.006 Millimeters in diameter So how does DNA this long fit into a set a cell with a diameter this small? in order for that to happen the DNA material has to be Condensed and compact and packaged in order for it to be fit into this nucleus and That's what actually happens. So in eukaryotes or DNA is Consist of DNA plus chromatin material plus proteins. So chromatin as you will know is actually DNA plus protein and That's how Orgenetic material exists in our nucleus. So it's chromatin is equal to DNA Plus protein and The protein that is predominately found in the in the chromatin is actually called histones so DNA Get wrapped around histones in order to start the compaction or the condensation process and As the process of packaging continues. So you have here Where you have less packaging Sorry packaging To here being the most package DNA in its most package form So from less packaging to most packaging you have to have a series of Coiling that coil and repeated coiling until you get to this point where the chromosome is in its most condensed form So this represents a chromosome in metaphase of the cell cycle in metaphase of After after you have DNA replication occurring So this is one molecule that got condensed and then it would form this this one chromosome But after you have duplication in the form of DNA replication and then you have further Condensation you have the chromosome in its most package form during metaphase So this is how our DNA actually looks in the eukaryotic cell It's actually found in the eukaryotic cells as chromosomes