FCGMOs Transgenes Basics

Robert Vavala Author

03/27/2018 Added

361 Plays

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Basic information about transgenes

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[00:00:00.500]Learners, we now have an understanding
[00:00:04.960]of mutations and how genetic changes,
[00:00:08.910]genetic modifications that we call mutations,
[00:00:11.770]can result in the alteration
[00:00:14.960]of the protein coding capabilities of genes.
[00:00:19.730]And that can result in either favorable
[00:00:22.720]or unfavorable changes
[00:00:24.900]in the living things that we're interested in.
[00:00:27.680]Now we want to take our understanding
[00:00:30.650]of how genes work and how genes can be mutated
[00:00:34.430]and apply that to understanding the genetic modification
[00:00:38.020]that we call transgenes.
[00:00:39.310]So let's concentrate again on our stretch of the chromosome
[00:00:42.430]in a living cell, and this is a stretch
[00:00:46.050]that might contain the information
[00:00:48.980]that's a part of a single gene.
[00:00:51.310]What a genetic engineer, an expert in the process
[00:00:54.780]of genetically modifying living things with transgenes,
[00:01:00.182]will do is they will find a gene
[00:01:03.760]that they would like to add to this chromosome,
[00:01:08.240]and then in a test tube they will design the gene
[00:01:12.620]to meet a specific purpose.
[00:01:14.960]They will have to design the gene
[00:01:16.650]so it will have a promoter,
[00:01:18.310]an on/off switch that will turn the gene on
[00:01:22.190]in the right kind of cell in this living organism
[00:01:25.480]at the right time.
[00:01:26.620]And then they'll have to have a second part of the gene,
[00:01:30.580]the transgene, called the coding region,
[00:01:34.950]and that's the actual DNA sequence
[00:01:37.540]that provides the genetic code for building a protein.
[00:01:41.430]So they will construct this DNA molecule
[00:01:45.740]in a test tube.
[00:01:47.630]And then just like the DNA can be replicated
[00:01:50.840]in a living cell,
[00:01:52.180]they can do a DNA replication procedure in their test tube
[00:01:56.990]and make lots of copies of this particular gene.
[00:02:00.870]We're calling it a transgene
[00:02:03.070]because trans means this gene originated
[00:02:07.630]from some other living thing.
[00:02:09.540]And what they're gonna do is take
[00:02:11.520]and introduce these copies into a living cell
[00:02:14.900]and then hope the chromosome breaks
[00:02:17.530]in some location in the cell.
[00:02:20.580]And when it breaks, there's a natural repair process
[00:02:26.080]that occurs with the DNA,
[00:02:27.540]but if you have copies of the transgene present
[00:02:30.600]in the cell, one of those transgene copies can be
[00:02:35.310]integrated into the repaired chromosome.
[00:02:38.100]So now this chromosome has all the genes
[00:02:40.430]that it originally had, but you've added one new gene.
[00:02:44.880]And because that gene came from somewhere else,
[00:02:48.270]somewhere besides this living thing, we call it a transgene.
[00:02:53.340]Trans just means you've transferred it from somewhere else.
[00:02:57.260]Okay, so that is what a transgenic modification is
[00:03:02.370]where you've added an additional gene to the chromosome,
[00:03:07.550]therefore added one gene to the genes
[00:03:10.090]that are already there.
[00:03:11.860]And once that gene is there,
[00:03:13.840]even though I'm showing it to make it easy to visualize,
[00:03:17.960]a different color, I'm drawing the DNA double helix
[00:03:22.870]in a little different style,
[00:03:25.210]this DNA molecule will function the same
[00:03:28.190]as all the other DNA that makes up the chromosome.
[00:03:30.720]It'll be replicated every time the chromosome replicates.
[00:03:34.040]The coding region of the gene uses a universal genetic code,
[00:03:38.900]so whatever organism this coding region came from,
[00:03:43.848]the new organism knows how to read it
[00:03:45.960]and build the appropriate protein
[00:03:48.190]because the genetic code is a universal code.
[00:03:51.520]So this is why transgenes work,
[00:03:53.920]why you can move transgenes from one species to another.
[00:03:58.030]It's because in biology there is just one genetic code.
[00:04:02.140]All living things use the same genetic code.
[00:04:06.050]So, transgenes will provide an additional set
[00:04:10.200]of instructions to make one additional protein.
[00:04:13.720]Transgenes then add one gene to the genome.
[00:04:18.320]Transgenic would be the term then that we would use
[00:04:21.690]to describe a living thing
[00:04:24.120]that has this one additional gene.
[00:04:26.950]So let's think a little bit
[00:04:28.740]about the magnitude of this genetic change.
[00:04:31.340]Is this a bigger genetic change than a mutation?
[00:04:35.280]Yeah, it is.
[00:04:36.113]We're not just changing the sequence of the nucleotides
[00:04:39.530]that are already present.
[00:04:41.280]We're adding an additional gene.
[00:04:44.020]So certainly it's a bigger genetic change than a mutation.
[00:04:49.460]However, if we think about the sizes of genomes,
[00:04:53.730]a genome, all the genes that make up all the chromosomes
[00:04:57.610]in a living thing, such as a pig or a soybean plant,
[00:05:02.050]there's about 30,000 genes.
[00:05:04.440]How many genes would be in a transgenic version
[00:05:07.170]of that living thing?
[00:05:09.060]One more.
[00:05:09.900]Okay, so it is a different kind of genetic change.
[00:05:14.610]It probably isn't involving the magnitude
[00:05:18.940]of genetic change that a lot of people imagine.
[00:05:22.690]Transgenic or GMO,
[00:05:25.860]GMO is really a synonym to transgenic,
[00:05:28.640]are living things with one or more transgenes.
[00:05:32.723]So really the key here,
[00:05:34.070]the most important difference is that this gene
[00:05:37.870]that you've added to the genome doesn't naturally occur
[00:05:42.790]in that species, at least not constructed
[00:05:46.860]in this particular way with the promoter
[00:05:50.160]and the coding region design by the transgene.
[00:05:52.890]That's probably the biggest difference.
[00:05:55.510]Okay, so this now should give us the basis
[00:06:00.530]of comparing genetic modifications
[00:06:04.060]for mutations and transgenes
[00:06:06.240]and then allow us to contrast non-GMOs with GMOs,
[00:06:09.940]so we'll do that next.

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FCGMOs Transgenes Basics

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