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DNA Structure and Replication
In this lecture, Professor Richard Bowater (University of East Anglia) talks about DNA, its structure, its replication and how it can code for proteins. To do so, we: (i) discuss the microscopic structure of DNA, looking at what each monomer (nucleotide) is made of; before (ii) understanding the history of its discovery and the macroscopic structure; following onto (iii) DNA polymerase and its role in DNA synthesis; which then goes on to (iv) the coding and non-coding sections of DNA and how four nucleotides code for 20 amino acids; before (v) diving into the step-by-step process of how new nucleotides are added to DNA; and then finally (vi) understanding how DNA can be mutated and damaged, and some of the implications this can have on the proteins it codes for.
Overview
In the first mini-lecture, we are introduced to what DNA is by first discussing its function as the ‘instructions of life’, allowing cells to grow and divide. We talk about DNA (and RNA) as biological polymers, and discuss other examples of natural polymers such as proteins. To continue, we talk about the processes DNA undergoes all the time that lets it carry out its functions. We discuss the central dogma, as well as the importance of replication, recombination and repair in the maintenance of cells and DNA. To finish off, we look at the chemical structure of DNA, diving into the structure of a nucleotide, what they are made of, and the four different nucleotides we come across in DNA.
Hello.
00:00:06My name is Professor Richard Burr Water and I teach biochemistry
00:00:06molecular biology at the University of East Anglia in Norwich.
00:00:09So today I'm going to tell you about D N A.
00:00:12And how the structure of DNA is important for all of
00:00:15the processes that is involved in in in the Cell.
00:00:17So D. N A is one of the bio molecules that are found in all cells.
00:00:21And so there are a group of biomolecules that are
00:00:25critical for all cells to be able to function properly.
00:00:28As I've already said, D N A is one of them.
00:00:30Then there's another similar type of molecule called RNA,
00:00:32but other molecules are important are proteins, carbohydrates and lipids.
00:00:35But I'm going to focus on D N A in my lecture,
00:00:41and occasionally I'll mention some of those other other molecules.
00:00:44So D n A stands for deoxyribonucleic acid, uh, to give it its full chemical name, RNA,
00:00:47just for for interested a very similar type of molecule,
00:00:54both chemically and also in its name.
00:00:58So RNA stands for ribonucleic acid,
00:01:00so DNA is found in all cells,
00:01:03and it's often referred to as the instructions for life
00:01:06for any cell to be able to grow and divide.
00:01:09But it's also important for passing information on to daughter cells.
00:01:12That can be, uh, from the future, uh, sells for any particular organism.
00:01:15So throughout this short lecture series,
00:01:21I'll come on to tell you some aspects of the
00:01:23way that DNA is important in for for biology.
00:01:26Um,
00:01:29but I'm going to start off by defining some of the
00:01:30the important terms both in relation to D N A.
00:01:32But also for some of those other molecules that I've already referred to.
00:01:35So D. N A is a molecule that's referred to as a polymer.
00:01:40And what that means is it's made up of a number
00:01:44of repeating units of the same type of starting component,
00:01:48and the starting components are monomers
00:01:52and in terms of D n A. But also RNA.
00:01:55For for those molecules, the monomers are nucleotides.
00:01:58I'll come on to tell you more about nucleotides
00:02:01and their chemical structure in a little while.
00:02:03But just remember that point for now,
00:02:06that DNA is a polymer that's made up from the monomers of nucleotides.
00:02:08Just by comparison,
00:02:13we can also see that some of those other molecules are important inside cells.
00:02:14They're also polymers.
00:02:17So, for example,
00:02:19protein is a polymer that's made up of the amino acids as it's Monica.
00:02:20So again, the monomer, the amino acid, builds up to form the larger molecule,
00:02:26which is the protein.
00:02:31So that's quite a common theme that we see
00:02:32for Many types of molecules are important for cells
00:02:34that they build up to form larger molecules from
00:02:37much smaller molecules that are the basic components.
00:02:41What that tells us is DNA itself is quite a
00:02:46complicated molecule because it's formed from these many different nucleotides,
00:02:49the build up to form the larger molecule.
00:02:54Now, those as those nucleotides come together, they take on a larger structure
00:02:57that I'll come on to discuss with you in detail. In a little while,
00:03:02that structure of DNA is absolutely critical for all of
00:03:08the processes that DNA is involved with inside the cell,
00:03:11and later I'll tell you more about replication and
00:03:14also some other processes such as repair and recombination.
00:03:17They are also important for for all cells. The functions that D. N A.
00:03:21Is involved in in all cells are also related to some
00:03:26of the functions that those other molecules are involved in,
00:03:29uh and so, for example,
00:03:31we see that DNA provides instructions to form RNA copies of itself.
00:03:33So the instructions with Indiana go on to form similar types of instructions in RNA,
00:03:38and then RNA provides instructions for, uh, making proteins.
00:03:43So those processes that make DNA into RNA and
00:03:49RNA into protein they also have their own names.
00:03:52So DNA being converted to RNA is referred to as transcription
00:03:55and RNA being converted into proteins that's referred to as translation
00:03:58and the links between all of these processes they
00:04:03referred to as the central dogma of molecular biology.
00:04:06So what we see is that D. N A. Has the instructions to code for RNA.
00:04:09That's the process of transcription and RNA as the instruction
00:04:13to code for protein through the process of translation.
00:04:16But we now know that there are more links between those molecules that
00:04:19we initially understood from the early experiments up to the 19 sixties.
00:04:23So, of course,
00:04:28it's important that we think about the fact that
00:04:29DNA contains the instructions to make more DNA molecules.
00:04:31So that's the process of replication, and I will come on to say more about that later.
00:04:34Um, but also, we now know that are in some cases,
00:04:38are in a can be used to make DNA copies of itself,
00:04:42and that's a process referred to as reverse transcription.
00:04:46Um,
00:04:50I'm not going to say too much about transcription or reverse transcription here,
00:04:50but I really just wanted to highlight that.
00:04:55We now know a lot more about these processes.
00:04:56Uh,
00:04:59and it's much more complicated than was originally thought when
00:04:59the DNA structure was first solved in the 19 fifties.
00:05:03I'm going to come on to discuss how DNA molecules
00:05:07synthesised new DNA molecules in the process of DNA replication.
00:05:10But before coming on to that,
00:05:13it's useful to think about how it is that the monitors the nucleotides,
00:05:14come together to form the nucleus acids.
00:05:20So as I've already mentioned, the monomer of is a nuclear tired.
00:05:23But the nucleotide itself is made up of different types of chemical groups,
00:05:27so each nuclear tired is made up of a base, a sugar
00:05:32and a phosphate group, and sometimes more than one phosphate group
00:05:38the basis of the parts that are really critical for DNA because they
00:05:43contain the sequence information that different
00:05:46differentiates one DNA molecule from another,
00:05:49and for the basis we have two types of bases, some of them are referred to as Puritans,
00:05:52and some of them are referred to as primitive means.
00:05:56The pure in bases in DNA are adenine,
00:05:59or a as it's often referred to guanine or G as as it is often referred to.
00:06:02And the perimeter in bases are cytosine, referred to as C
00:06:07and thiamine, referred to as T
00:06:11just for interest.
00:06:15It's also useful to highlight that RNA contains, uh,
00:06:15RNA nucleotides contain the same types of bases, except that in RNA,
00:06:20thiamine is replaced by yourself, which is referred to as EU.
00:06:25Now those bases come together.
00:06:28They're joined with the sugar, which is a five carbon sugar referred to as ribose,
00:06:30and one or more phosphates.
00:06:35The phosphates are attached to the sugar at certain
00:06:37parts of a certain chemical groups within that sugar,
00:06:40and that leads to some polarity within the molecule.
00:06:44I'll say more about this when I come on when I come to discuss replication,
00:06:47but it's important to recognise that one end of
00:06:52the molecule has a phosphate group attached to it
00:06:54and the other end of the nuclear tired as a hydroxyl group attached to it,
00:06:57and those become important during DNA synthesis
00:07:02
Cite this Lecture
APA style
Bowater, R. (2022, September 28). DNA Structure and Replication - Overview [Video]. MASSOLIT. https://massolit.io/courses/dna-structure-and-replication
MLA style
Bowater, R. "DNA Structure and Replication – Overview." MASSOLIT, uploaded by MASSOLIT, 28 Sep 2022, https://massolit.io/courses/dna-structure-and-replication