Chapter 21: Biotechnology

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Imagine stepping into a world where we're not just watching life happen, but actively shaping it.

For millennia, humans have influenced nature, right?

From the earliest farmers picking the best crops, breeding the strongest animals,

selective breeding.

That's ancient.

But what happens when our understanding of life like right down to the genetic code itself just explodes?

How does that change what's even possible?

That's the crux of it.

So today we're diving deep into this fascinating frontier,

biotechnology.

Our guide is largely Robert J.

Bricker's genetics analysis and principles.

We want to unpack the core ideas,

the ingenious methods, and the really incredible applications.

Things that are revolutionizing medicine, agriculture,

even believe it or not, our pets.

Biotechnology basically just means using living things for human benefit.

Simple enough.

But since the 1970s, wow, it's been transformed.

How so?

Molecular genetics.

Suddenly we have the tools, the recombinant DNA tech, to engineer organisms at a really fundamental level.

So now we talk about genetically modified organisms, GMOs.

They've got new genetic material added in.

And if that new DNA, that transgene, comes from completely different species, then we call it a transgenic organism.

And just one transgene, well, it can change everything.

So let's start small, microorganisms.

These tiny powerhouses, often overlooked, but they're kind of the unsung heroes here, aren't they?

Absolutely.

We've always used microbes, you know, making cheese, wine, beer, finding antibiotics.

Standard stuff.

Right.

But now, with genetic engineering, we can actually instruct them to build these incredibly complex human molecules, things vital for our health.

And the perfect example, I think, has to be human insulin.

Before this engineered stuff, diabetics relied on insulin from pigs or cows, right?

Exactly.

And that worked for many, but for some people?

Well, it caused allergic reactions.

Not ideal.

So how did they solve it with microbes?

It was truly groundbreaking.

They used E.

coli, common gut bacteria.

See, human insulin has two protein chains, A and B.

Scientists inserted the DNA code for chain A and separately for chain B into the E.

coli.

But here's the really clever bit.

They attached each insulin gene piece to a larger, stable E.

coli protein gene.

Why do that?

Well, inside the bacteria, these small human protein chains would get chewed up, degraded really fast.

Oh, okay.

So fusing them to a big bacterial protein protected them, created these fusion proteins.

Like a bodyguard.

Sort of, yeah.

Then after the bacteria churned out lots of these fusion proteins, they could purify them and use a chemical cyanogen bromide to precisely snip off the insulin chains.

Neat.

Purify the A and B chains, mix them together under the right conditions, and boom.

They fold correctly, form the right bonds, and you get active human insulin, identical to what our body makes.

Amazing.

And that was GenTech back in the early 80s.

That's right.

GenTech, they actually did some adistatin first, another hormone, but insulin was the big one.

FDA approved in 82.

The first ever genetically engineered drug.

It really opened the floodgates.

So this technique wasn't just for insulin then.

What else came out of it?

Oh, loads of critical medicines.

Think tissue plasminogen activator.

TPA dissolves blood clots after heart attacks or strokes.

Crucial.

Factor 8th for hemophilia treatment,

erythropiatin or EPO for anemia, helps boost red blood cell production, all made safely and efficiently by these engineered microbes now.

It's incredible, but they're not just medicine factories, are they?

You mentioned them being like frontline defenders, biological control.

Exactly.

Biological control is basically using one organism, or its products, to combat pests or diseases, often as a greener alternative to chemical pesticides.

Okay.

A great example is fighting crown gall disease in plants.

It's caused by a bacterium called agrobacterium tumifatians.

Right.

Scientists use a different harmless agrobacterium species, radiobacter, which naturally produces an antibiotic that kills the disease -causing one.

So good bacteria versus bad bacteria.

Pretty much.

And they even tweaked the good one so it can't accidentally transfer its antibiotic -producing ability to the bad one.

Makes it safer.

That's smart.

And what about Bacillus thuringiensis?

That name, bleak, pops up a lot.

Ah, bt.

Yes.

It's a superstar in biological control.

It's a naturally occurring soil bacterium.

Okay.

And it produces these protein crystals that are toxic, specifically to certain insects like caterpillars and beetles.

The key is, they're harmless to plants, humans, pets,

beneficial insects like bees.

Really targeted, then.

Very targeted.

The insect eats the plant material with a bead on it.

The toxin gets activated in its gut,

paralyzes the digestive system, and the insect stops feeding and dies.

It's a natural pesticide.

And I guess we'll hear more about bt later when we talk plants.

We certainly will.

Its genes have become very important.

And one more microbial trick.

Cleaning up our messes.

Bio -remediation.

That's right.

Using living organisms, mostly microbes, to break down or detoxify pollutants in the environment.

How does that work?

Well, sometimes they just transform the pollutant into something less harmful.

Other times they completely bio -aggrade it, break it down into simple, non -toxic molecules, think sewage treatment that's classic bio -remediation, used for over a hundred years.

There's also potential for cleaning up oil spills, industrial waste, heavy metals, though it can be complex.

Remember that oil -eating bacterium patented back in 1980?

Vaguely, yeah.

It got a lot of hype.

But commercial success was limited.

Crude oil is a messy mix of thousands of compounds, and that bacterium could only handle a fraction of them.

Still, the principle holds enormous promise.

Okay, so from these microscopic workhorses, let's scale up.

Genetically modified animals.

These feel like maybe more dramatic examples of GMOs.

They certainly capture the imagination.

A really striking example is that transgenic Atlantic salmon.

The faster growing one.

Exactly.

It carries a gene that regulates growth hormone borrowed from the Chinook salmon.

And the result?

It grows year -round, not just seasonally, like normal Atlantic salmon.

Reaches market size much, much faster.

That's a significant change.

So how do scientists actually alter an animal's genome?

What are the main ways?

Well, broadly speaking, there are two main strategies.

First, you have gene modification.

This is where you tweak an existing gene.

Like editing it?

Yes, sort of.

You might use tools like CRISPR -Cas nowadays to maybe inactivate a gene that's a knockout to see what happens when it's missing.

Or you could introduce a very specific mutation, perhaps one known to cause a human disease, to create an animal model for study.

Okay, modifying what's already there.

What's the other way?

The other way is gene addition.

Here you're actually inserting a whole new cloned gene into the animal's genome.

This could be an extra copy of a gene the animal already has.

Or it could be a gene from a completely different species, like that salmon example.

Let's focus on adding genes for a second.

You hear about gene knock -ins, especially in mice.

How precisely do they add that gene?

Right, a knock -in is often about precise insertion.

Typically, they take the cloned gene they want to add and they flank it with DNA sequences that match a specific known location in the mouse genome.

They inject this construct into a fertilized mouse egg.

Through a natural process called homologous recombination, the cell uses those matching sequences to guide the new gene into that specific spot.

And why aim for a specific spot?

Often they choose a safe harbor site, a spot known not to disrupt any essential mouse genes.

This helps ensure the added gene works properly and consistently, and you get a clear result without unexpected side effects from disrupting something else.

Then the modified embryo goes into a surrogate mother.

And sometimes the results are, well, quite bright, like the glowfish.

Huh, exactly.

Glowfish are a perfect, very visible example of gene addition.

They're zebrafish carrying genes from jellyfish or sea coral that make fluorescent proteins.

So they actually glow, green, red.

Yep, vibrant green, red, yellow, depending on the specific gene added.

Originally, the idea was maybe for pollution detection, they'd glow in contaminated water.

Oh, interesting.

But the ones that glow all the time caught the public eye.

In 2003, they became the first genetically modified organism ever sold as a pet.

Still popular today.

Fascinating detour.

But getting back to the science, these knockouts and knock -ins in mice seem crucial for understanding basic biology and human disease.

Absolutely essential.

Knocking out a gene tells you what happens when it's missing its function.

Though, sometimes you don't see an obvious effect.

Why is that?

Could be the gene only plays a small role.

Or maybe another gene compensates for its lost gene redundancy.

Or perhaps the effect only shows up under very specific conditions, like stress or a particular diet.

OK.

And how does this directly help with human health?

These mouse models.

They let us create mouse models of human diseases.

This is huge.

Take sickle cell disease.

Early attempts just adding the human mutant gene didn't quite work.

Didn't replicate the disease well.

Right.

But then researchers got really sophisticated.

They did a knock -in of the human genes, both the normal alpha globin and the mutant beta globin that causes sickle cell.

And they did knockouts of the mouse's own alpha and beta globin genes.

Wow.

Replacing the mouse genes with human ones.

Essentially, yes.

So these mice ended up producing primarily human hemoglobin, including the faulty sickle cell version.

And crucially, they developed the major symptoms we see in humans with sickle cell disease.

That must have been a massive step forward for research.

Immense.

It provided an invaluable tool to study how the disease progresses and, really importantly, to test potential new therapies.

Looking ahead, another area generating buzz is xenotransplantation, using animal organs for humans.

That's the idea.

Primarily using pig organs, because they're a similar size to ours.

The huge barrier, though, has always been the human immune system fiercely rejecting the pig tissue.

Right.

But genetic modification is tackling this.

Scientists identified a key pig gene for an enzyme called 133 -agalactosyltransferase that puts specific sugar molecules on pig cells that our immune system really hates.

OK.

So they've used gene knockout technology to create pigs that lack this gene.

Their organs don't have that major rejection trigger.

It doesn't solve all the rejection issues.

But it's a massive step towards making pig -to -human transplants feasible.

Incredible.

And one last animal application.

Molecular farming.

Turning livestock into medicine factories sounds wild.

It does, but it's happening.

Molecular farming is engineering livestock, often sheep, goats, or cows, to produce medically important human proteins in their milk.

Why do it that way instead of using bacteria, like with insulin?

Great question.

Some complex human proteins need specific folding or modifications,

like adding sugar molecules, to work correctly.

Bacteria often can't do that properly, but animal cells being eukaryotic like ours can.

Ah.

So the quality is better.

Potentially, yes.

And the yields can be huge.

Think about a dairy cow.

She produces thousands of liters of milk a year.

If you engineer her to produce even, say, one gram of a therapeutic protein per liter,

that's a lot of medicine.

So how do they target it just to the milk?

They link the human gene they want to express to a regulatory DNA sequence, a promoter that is normally only active in mammary gland cells during lactation, like the promoter for beta -lactoglobulin, a common milk protein.

Clever.

Inject that construct into an egg, create a transgenic female animal, and when she lactates, her milk contains the desired human protein, which can then be purified.

Things like human lactoferrin, TPA, antibodies, factor IX, they're all being produced or developed this way.

Okay.

Shifting gears now to topics that have really captured public attention and stirred up quite a bit of ethical debate.

Reproductive cloning and stem cells.

Definitely two hot -button topics.

First, let's be clear.

Gene cloning, making copies of DNA in the lab, is different from reproductive cloning, which aims to create a genetically identical individual.

Like identical twins, but done intentionally.

Exactly.

Twins are natural clones, and cloning plants from cuttings is easy.

We've done that forever.

But cloning a whole mammal from an adult cell, that was science fiction for a long time.

Until Dolly the sheep.

That changed everything, didn't it?

Dolly, born in 1996, was a watershed moment.

Ian Wilmot and his team in Scotland pulled it off.

How did they actually do it?

Okay.

They took a mammary cell's utter cells from an adult fin dorset sheep, grew them in the lab.

Then they took an unfertilized egg cell from a different sheep, the Scottish blackface.

Right.

They carefully sucked out the nucleus from that egg cell, removing its genetic material, left an empty egg, basically in a nucleated egg.

Then the crucial step.

They fused one of the donor mammary cells, which has a full set of adult DNA, with the empty egg cell using electric pulses.

And that kick started development.

It did.

The fused cell started dividing as if it were a normally fertilized zygote.

They let it develop into an early embryo in the lab, then implanted it into the womb of another surrogate mother sheep.

And Dolly?

And 148 days later, Dolly was born.

A lamb genetically identical not to the egg donor or the surrogate mother, but to the sheep who donated the original mammary cell.

Proof that an adult cell could be reprogrammed to create a whole new individual.

Was huge news.

But then questions started coming up about Dolly's health, specifically her chromosomes, didn't they?

That's right.

There were concerns about premature aging.

When Dolly was about three years old, researchers looked at her telomeres.

Those are the protective caps on the ends of chromosomes.

Exactly.

They naturally shorten each time a cell divides, kind of like a biological plaque.

Dolly's telomeres look shorter than you'd expect for a sheep her age.

They seem more like those of an older sheep.

Why would that be?

Well, the thinking was, the nucleus came from a mammary cell of a six -year -old sheep.

That cell had already undergone divisions.

Its telomeres had already shortened.

And then it divided more in the lab before fusion.

So Dolly essentially started life with an older set of chromosomes, genetically speaking.

Did this affect her health?

She developed arthritis relatively young and then died prematurely at age six from a common sheep lung disease.

It definitely fueled concerns that cloned animals might age faster or have health issues, though its complex subsequent cloning research in other animals like mice and cattle has shown conflicting results about telomere length and lifespan.

Some cloned animals seem fine, others show abnormalities.

So where does that leave cloning applications and the ethics today?

Well,

practically cloning could be used in agriculture to replicate prize -winning livestock, creating genetically uniform herds.

Faster genetic improvement, maybe.

But uniformity sounds risky too, like for diseases.

Exactly.

A big downside is that if the whole herd is genetically identical, they're all equally susceptible if a new disease hits.

You could wipe them out.

And human cloning.

That remains hugely controversial.

Ethical arguments range from deep moral objections, concerns about identity and family structures, to some suggesting potential uses, say, for infertile couples wanting a genetically related child.

But public opinion has generally been negative, leading most countries to ban reproductive cloning or heavily restrict research.

It's still a very charged issue.

Okay, let's pivot to another area with huge promise and ethical dimensions.

Stem cells.

Stem cells are fascinating.

They're essentially the body's internal repair and regeneration system.

Undifferentiated cells with two defining features.

Which are?

One, they can divide, basically indefinitely, to make more stem cells.

Two, they have the ability to differentiate, to mature, into various specialized cell types, like muscle cells, nerve cells, blood cells.

How do they maintain their own numbers while also producing specialized cells?

Often through asymmetrical division.

When a stem cell divides, one daughter cell might remain a stem cell, replenishing the pool, while the other daughter cell is signaled to start differentiating down a specific path.

Okay, makes sense.

Are there different kinds of stem cells?

Yes, we categorize them based on their potency, their potential to differentiate.

Like a hierarchy?

Sort of.

At the top, you have totipotent cells.

This is really just the fertilized egg and the first few cells after it divides.

They can form every cell type, including the placenta, meaning they can develop into a whole new organism.

Okay, total potential.

Then come pluripotent stem cells.

These are key for research.

Embryonic stem cells, ES cells, derived from the inner cell mass of an early embryo called a blastocyst, are pluripotent.

They can become almost any cell type in the body, but they can't form the placenta, so not a whole organism on their own.

Got it.

What's next?

Multipotent stem cells.

These are typically found in adult tissues that are often called adult stem cells.

They can differentiate into several related cell types, but their potential is more limited.

Think of hematopoietic stem cells in bone marrow.

They can become all the different types of blood and immune cells, but not, say, nerve cells or liver cells.

So more specialized already.

Right.

And finally, unipotent stem cells.

These can only differentiate into one specific cell type.

For example, certain stem cells in the skin just make skin cells.

So this differentiation potential is key for medicine, right?

How could we use them to treat diseases?

The therapeutic potential is enormous.

We already use multipotent stem cells routinely in bone marrow transplants.

They rebuild the entire blood and immune system for patients with certain cancers or blood disorders.

That's already happening.

What about the future?

The hope is to use stem cells, particularly pluripotent ones, to replace cells damaged by disease or injury.

Imagine generating new nerve cells for Parkinson's or spinal cord injuries, new heart muscle cells after a heart attack, insulin -producing cells for diabetes,

cartilage for arthritis,

skin for burn victims.

The list is long.

Why are embryonic stem cells often seen as having more potential for this than adult stem cells?

Mainly because ES cells are easier to isolate, grow in large numbers in the lab, and, being pluripotent, they have the potential to become any cell type needed.

The big challenge, though, is controlling their differentiation reliably, making sure they become the exact cell type you want and not something else, or worse, forming tumors.

Adult stem cells are often harder to find, harder to grow in culture, and more limited in what they can become.

But this brings us back to the ethical debate, especially about the source of embryonic stem cells.

Exactly.

ES cells are typically derived from the inner cell mass of blastocysts.

These are often embryos created through in -vitro fertilization, IVF, that are left over, not needed for pregnancy, and would otherwise likely be discarded.

So using tissue that wouldn't become a person anyway.

That's one perspective.

The argument is that it's ethically justifiable, even imperative, to use this material, which cannot develop into a person on its own, for research that could save lives and alleviate suffering.

But there are strong objections, too.

Absolutely.

For those who believe that a human embryo has the moral status of a person from conception, destroying it to harvest stem cells is morally wrong, regardless of the potential benefits.

It's a deep ethical conflict with very different views on the moral status of the early embryo.

A real dilemma.

But wasn't there a discovery that might offer a way around this particular ethical hurdle?

Yes.

A truly revolutionary one.

Induced pluripotent stem cells, or IPS cells.

In 2006, Shinya Amanaka in Japan made a stunning discovery.

What did he do?

He showed that you could take ordinary adult cells.

He used skin fiber blasts from mice and reprogrammed them back into a pluripotent state, essentially making them behave like embryonic stem cells.

Oh!

Just like that.

By introducing just four specific regulatory genes into the adult cells.

These genes basically reset the cell's developmental clock.

Wow.

So you can make ES -like cells without using embryos.

Exactly.

This discovery was huge because it offers a potential way to get pluripotent stem cells for research and therapy, maybe even patient -specific cells, reducing rejection risk without needing to use human embryos.

It bypasses many, though not all, of the ethical concerns surrounding ES cells.

It won the Nobel Prize, and it's a major focus of research now.

Okay, for our final deep dive, let's turn to genetically modified plants.

This is where biotech really hits our dinner plates, right?

Reshaping agriculture.

Absolutely.

Humans have been modifying plants through selective breeding for thousands of years, picking the best seeds, crossing varieties.

Making corn bigger, wheat hardier.

Right.

Modern molecular genetics just adds incredibly powerful and precise tools to that ancient practice.

And the uptake since the mid -1990s has been phenomenal.

By 2015, something like over a third of global cropland was planted with genetically modified varieties.

What kinds of useful traits are we actually engineering into these plants?

Whole range.

Mostly focused on agricultural benefits.

Big categories include plant protection.

Like defending against pests.

Yes.

Herbicide resistance is a major one.

Think of crops engineered to tolerate herbicides like glyphosate.

Farmers can spray the whole field, kill the weeds, but the crop survives.

Saves a lot of weeding.

Definitely.

Then there's disease resistance engineering plants to fight off specific viruses, often by giving them a piece of the virus's own coat protein gene.

Okay.

And of course insect resistance, mainly using those bitoxin genes we talked about earlier from psilis thuringiensis.

So the plant makes its own insecticide.

Nicely.

Buy corn and buy cotton are widespread.

The plants produce the toxin, insects eat the plant, ingest the toxin, and die.

It dramatically reduces the need for spraying chemical insecticides.

What else besides protection?

Improving plant quality.

Things like engineering tomatoes to soften more slowly, giving them a longer shelf life.

Or changing the composition, altering the oil profile in canola, for instance.

Or trying to boost nutritional value.

And maybe the most futuristic sounding.

Using plants to make completely new products.

Yeah, this is really exciting.

Engineering plants to produce biodegradable plastics in their tissues.

Or using plants as factories to produce vaccines, imagine edible vaccines for diseases like hepatitis B or cholera.

Or even producing pharmaceuticals, like human antibodies or interferons, right there in the plant biomass.

That sounds incredibly efficient.

But with GM crops being so widespread, there must be concerns, right?

What are the perceived risks people talk about?

There are definitely ongoing discussions and concerns.

One is the potential impact on non -target organisms, for example.

Could bait pollen harm beneficial insects like monarch butterfly larvae?

Those studies on this have had mixed results and interpretations.

Right.

Another concern is gene flow.

The possibility of trans genes spreading from the GM crop to wild relatives.

And then there's the potential for pests to evolve resistance to the engineered traits.

Like insects becoming resistant to bait toxins.

How is that managed?

The resistance issue.

Strategies involve things like planting refuges of non -beady crops nearby to maintain a population of susceptible insects.

Or increasingly stacking multiple different beet cocks and genes in the same plant,

making it much harder for insects to develop resistance to all of them simultaneously.

So despite the concerns, farmers keep using them.

Usage continues to increase globally, yes.

The perceived benefits for farmers, higher yields, reduced pesticide use, easier weed control have often outweighed the concerns for them.

But the public debate continues.

So practically speaking, how do scientists get these new genes into the plants?

What's the most common way to make a transgenic plant?

The workhorse method for many important crops relies on harnessing that bacterium we met earlier.

Agrobacterium tombfaciens.

The one that causes crown gall disease.

Very sane.

Naturally, this bacterium infects plants and transfers a piece of its own DNA called the Normally, this tDNA carries genes that cause the plant cells to proliferate and make food for the bacterium, forming that crown gall to her.

So scientists hijack this natural delivery system.

Exactly.

They've engineered the agrobacterium's plasmid.

They remove the tumor -causing genes from the tDNA segment.

In their place, they put restriction sites, specific DNA sequences where they can easily cut and paste their gene of interest.

They also include a selectable marker gene, usually something like resistance to an antibiotic, say, kanamycin.

Okay, so they build a custom tDNA package.

Then what?

They insert their desired gene, maybe the bait toxin, the herbicide resistance gene, into this engineered tDNA vector.

They put this vector back into agrobacterium.

Then they expose plant cells or small pieces of plant tissue to these modified bacteria.

The bacteria infects the plant cells and delivers the custom tDNA.

Precisely.

The agrobacterium transfers the engineered tDNA, carrying the desired gene and the marker gene into the plant cell's DNA.

Then, they kill off the bacteria using a different antibiotic.

And they grow the plant cells on a medium containing kanamycin.

Ah, so only the plant cells that successfully received the tDNA with the kanamycin resistance gene will survive.

You got it.

It selects for the successfully transformed cells.

The surviving cells, which now carry the new gene, can then be treated with plant hormones to regenerate them back into whole transgenic plants.

Every cell in that regenerated plant will carry the new gene.

That's a really elegant system using the bacterium's own trick against it, in a way.

Are there other methods besides agrobacterium?

Yes, definitely.

Especially for plants that agrobacterium doesn't infect easily, like some cereals.

One method is biolistic gene transfer, often called the gene gun.

Gene gun?

Sounds traumatic.

It kind of is.

You coat tiny metal particles, gold or tungsten, with the DNA you want to insert, and you literally shoot them at high velocity into plant cells.

Some particles penetrate, and the DNA can get integrated.

Wow.

Any others?

There's microinjection, using incredibly fine needles to inject DNA directly into cells.

Electrooperation uses brief electric pulses to create temporary holes in the cell membrane, allowing DNA to enter.

And sometimes researchers remove the plant cell wall first, creating a protoplast, which can make it easier to get DNA inside using chemicals.

So a whole toolbox exists.

We've really covered a lot of ground.

From bacteria making insulin,

to engineered salmon growing faster,

mice modeling human diseases,

livestock producing medicines.

Right.

And cloned sheep sparking ethical debates.

Stem cells holding promise for regeneration.

And fields full of crops designed to resist pests or herbicides.

It really shows how this ancient idea of using life to benefit us has been completely turbocharged by understanding genetics at the molecular level.

Absolutely.

This deep dive into biotechnology, drawing from Brooker's text, really highlights that.

It's a story thousands of years old, but the pace now, driven by molecular tools, is just incredible.

It's filled with ingenuity, real world applications.

And some pretty profound ethical questions that we're still grappling with, right?

Definitely.

The science keeps advancing, and the societal discussion has to keep pace.

The power, the possibilities, and also the responsibilities that come with being able to manipulate genetic material, they're immense.

It really makes you wonder, what's the next frontier going to be?

What else will we be able to do?

It's constantly evolving.

Well thank you for joining us on this deep dive today.

We hope it's left you feeling well informed, maybe a bit amazed, and perhaps inspired by where genetics is taking us.

It's certainly a field to keep watching.

And as always, a warm thank you for being part of the Last Minute Lecture family.