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Lecture Comments (2)

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Post by Bryan Cardella on January 29, 2015

NOTE: With regard to amniocentesis, the way that the homologous pairs of chromosomes are typically put together is by taking a photograph of the extracted chromosomes, and then physically manipulating the parts of the photograph to put the pairs together for viewing. This is much easier than physically grabbing each chromosome under a microscope and putting them side-by-side. Chromosomes are waaaay too small to grab with tweezers :-)

Genetics, Part II

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • Karotyping 0:04
    • Process to Check Chromosomes for Abnormal Characteristics
    • Done with Cells From a Fetus
    • Amniocentesis
  • Normal Karotype 2:43
  • Abnormal Karotype 4:20
  • Nondisjunction 5:14
    • Failure of Chromosomes to Properly Separate During Meiosis
    • Nondisjunction
    • Typically Causes Chromosomal Disorders Upon Fertilization
  • Chromosomal Disorders 10:52
    • Autosome Disorders
    • Sex Chromosome Disorders
  • Pedigrees 20:29
    • Visual Depiction of an Inheritance Pattern for One Gene in a Family's History
    • Symbols
    • Trait Being Traced is Depicted by Coloring in the Individual
  • Pedigree Example #1 22:26
  • Pedigree Example #2 25:02
  • Pedigree Example #3 27:23
  • Environmental Impact 30:24
    • Gene Expression Is Often Influenced by Environment
    • Twin Studies
    • Examples
  • Genetic Engineering 36:03
    • Genetic Transformation
    • Restriction Enzymes
    • Recombinant DNA
    • Gene Cloning
    • Polymerase Chain Reaction
    • Gel Electrophoresis
    • Transgenic Organisms

Transcription: Genetics, Part II

Hi, welcome back to, this is the lesson on genetics, part 2.0000

Something else related to genetics is Karotyping.0006

It is a process used to check chromosomes for abnormal characteristics, wrong number or damaged chromosomes.0009

Ideally, you should have 46 chromosomes in a developing baby, 23 from the sperm and 23 from the egg.0015

If there is a wrong number, it is a chromosomal disorder.0022

Damage to the chromosomes is also visible through a karotype.0026

I will show you some examples of what these things look like.0029

One example would be fragile X syndrome.0031

Chromosomes tend to look like this but fragile X syndrome, when you look at the bottom of the X chromosome,0035

it almost looks like they are more fragile, like it is almost about to falloff.0048

That is the characteristic look of that chromosomal problem on the X chromosome.0053

Karotyping is typically done with cells from a fetus.0058

Amniocentesis is the classic way that a karotyping is achieved.0062

This is how you actually get cells from the fetus and there is a risk to the mother.0067

It is only done in certain mothers.0073

For instance, I will get to this picture in a second.0075

If the mother is older, let us say early 40’s and older.0079

If there is a history of genetic defects in the family.0083

If the mother has taken certain medications, certain drugs during pregnancy0087

that can lead to a chromosomal problem being possible or more probable, then an amniocentesis would be done.0091

You would not typically do it on just any mother because there is a risk of damage to the baby.0097

There is a risk of miscarriage actually happening because of this.0103

Here is my little drawing of a pregnant woman.0106

Here is the baby inside, there is the placenta, the umbilical cord.0109

This is the uterus and the amniotic sac is enclosed in it, that is where the amnio comes from.0112

Amniocentesis, basically a needle is stuck into the abdominal region into the amniotic sac where there is amniotic fluid.0118

Inevitably, skin cells from the baby have come off into the amniotic fluid throughout to determine the pregnancy.0134

If you extract enough amniotic fluid, you are going to get cells from the baby inside of their.0142

You then take those cells and you culture them to make more cells.0148

You can extract the chromosomes, lay them out, puts the pairs together and see what you got.0153

You can diagnose certain disorders through this process.0159

Here is a normal karotype, if you are looking at this you might be thinking that these0165

do not look like those X shaped or butterfly shaped chromosomes that I have seen in the past.0170

What you are really seeing is, instead of this kind of cartoony duplicated chromosome, what you are seeing is this.0176

If you compare this structure to this, you can see that is what you are looking at.0190

There are different bending patterns on different chromosomes, different light and dark regions throughout the chromatids.0196

That is what you are seeing here.0205

Traditionally, when we talk about chromosome 1 through chromosome pair 23 which is actually sex chromosomes,0207

they are ranged in order from biggest chromosome down to the smallest.0214

The exception of course is the XX or XY, they just put the sex chromosomes as the 23rd pair, that last pair.0220

You can see chromosome pairs 1, 2, 3, 4 are very large compared to the ones down here.0228

This is an old karotype because if you count them out, there is 23 pairs a total of 46.0233

This is a boy because there is an X chromosome and there is a Y chromosome which is much smaller than the X.0241

It would be a girl if there were two of these.0246

Regarding sex chromosomes, you do not always get just XX or XY,0250

you can get an abnormal number of sex chromosome, certain ones missing.0254

I will talk about those disorders, a little bit later.0257

Here is an abnormal karotype, I realized that the images you are seeing are not as clear or distinct as the previous slide.0261

But this gets the job done, in terms of understanding what an abnormal karotype could look like.0268

All of them have the pair until you get to here.0277

There are 3 copies of the 21st pair and this is known as trisomy 21.0284

Trisomy meaning 3 bodies of the 21st which should be a pair but here there are 3.0292

That is results to Down syndrome, typically.0299

This is a boy with Down syndrome.0302

There are various characteristics that come along with that, I will discuss them a few later on in the lesson.0307

Nondisjunction, it is a failure of chromosomes to properly separate during meiosis,0315

that is what chromosomes are supposed to do.0320

When you are making sex sells, when you are making haploid cells, sperm or egg, you should end up with 23 chromosomes.0322

You have meiosis 1 and 2 that leads to having half the number and a unique variety of the genes from crossing over.0329

If you went over that with the cell division lessons earlier, you know what that is.0339

Here is the thing, the term nondisjunction tends to confuse people.0344

A junction, let us take it one part at a time, a junction is a coming together.0348

If two roads are joining in the one, you can call it a junction.0353

Disjunction would be the opposite, a separating.0357

Disjunction is a separating.0361

Nondisjunction would be the failure to separate, you are not getting the disjunction that you should be getting.0364

That is describing the separation of chromosomes, either pairs of chromosomes, or chromatids,0372

the sister chromatids, depending on what is happening in meiosis 1 and 2.0378

The resulting chromosome number in the gametes, the sperm or egg, end up being wrong.0382

You are not getting the 23 like you should.0386

You end up getting 24, 22, even more extreme errors in that.0388

This typically causes chromosomal disorders upon fertilization.0393

If you have nondisjunction resulting in 22 chromosomes in a sperm or egg,0396

if that particular sperm or egg meets with the corresponding gamete, you are not going to get 46 in the individual that results.0400

If you are wondering how these things occur, it is not entirely known exactly why did these errors occur.0410

They are not entirely random.0417

In females, since the eggs, the ova actually begin developing while that woman is inside of her mother in the uterus.0419

One of the theories about why it is that women in their 40’s and early 50’s,0428

why nondisjunction tends to happen more in them compared with men of the same age is because those cells are literally older.0434

Those cells have been arrested in development, they have been un-paused until they are ready to be ovulated.0441

Upon ovulation, that meiosis finishes.0447

Since the cells are older, it is more likely for some errors to happen when their chromosomes0452

actually be in the fully separated and finish out meiosis.0457

In men, you have continuous making of new sperm from puberty onwards.0460

As a male gets much older, he is making less and less sperm because of less testosterone available from the testicular region.0468

I’m not saying that men are not immune to nondisjunction.0476

On average, it just hits them a little bit later on in life.0479

Regarding nondisjunction, it can happen in meiosis 1 and 2.0485

In this particular case on the left, it is actually happening in meiosis 2.0489

Here you have the duplicated diploid.0494

We are saying that the diploid number is actually 2.0498

Here is the two chromosomes duplicated.0507

The first meiotic event results in this.0510

Meiosis 2, then you have separation of those sister chromatids, that happens here correctly but that did not happen here.0515

You can see that these two chromatids ended up in this resulting egg or oocyte and this one not.0523

This one is actually missing the chromosome.0534

When this sperm, with the right haploid number fertilizes, there is no red piece to go along with it.0537

We would say that, this one here is N -1, it is missing that N number.0543

This sperm is actually N, what we end up getting here is one less than you should for the diploid.0556

This one here, you would say N +1, you actually have too many here,0562

one too many because there should only be this number here.0569

If the diploid number is 2, the haploid number is 1.0573

These, this one too, these are N and they should be.0576

N + N= diploid 2N, N + N = diploid.0583

These actually end up being the right number of chromosomes in the resulting zygote, these do not.0587

This one here, this is an error in meiosis 1 which actually tends to be even worse downstream0594

because it happens earlier on, it affects all the cells after it.0602

In this case, instead of separation of the pair that should be happening, it is not happening here.0605

You have both chromosomes, both of the duplicated chromosomes going to this side, nothing here.0614

Just devoid of it.0619

Here you got, like I said earlier, this is N + 1, N + 1, both of these are N -1.0623

All of them, even if the sperm is healthy and has the right number of chromosomes,0635

the haploid number, all of them are off of what they should be.0641

Here they are missing the maternal chromosome.0645

Here they have one too maternal chromosome.0648

Here are some specific chromosomal disorders.0653

They are just the tip of the iceberg, there a lot of chromosomal disorders.0655

I’m going to give you some examples.0659

Some autosome disorders or autosomal disorders meaning not affecting the sex chromosomes, defecting pairs 1 through 22.0661

Down syndrome, as I mentioned earlier, can result from trisomy 21.0669

If you are wondering, is this from the male or female, it can be either.0673

That 21st chromosome in the sperm and the egg, there should just be 1.0678

So that when they come together in the zygote, there you have the pair, the 21st pair.0682

There is 1 too many in the sperm or 1 too many in the egg.0686

This is a child who has Down syndrome, there is some characteristics that tend to be shared by people who have Down syndrome.0690

There is a similar look in their faces, regardless of what race they are.0696

It is safe to say that, in the 21st pair there are genes that affect the shape of the skull.0702

Because, the look of your face really has a lot to do with how your skull bones are,0708

the muscles on top of that, and the skin on top of that.0712

Whatever it is about that 21st pair definitely has to do with the facial region.0715

Also, a common characteristic with Down syndrome individuals is mental difficulty.0722

It is going to take them longer to learn certain tasks,0729

they are going to be developmentally very behind children with the same age.0732

There is someone on my high school with Down syndrome.0737

I hear him graduating in my class but he was actually 20 or 21 at that time,0740

when we graduated from high school most of us were 18.0746

People with Down syndrome, they can learn tasks like other people, it just takes them a lot longer.0749

The parents, it requires a lot more patience on their behalf.0755

Spina bifida literally means split spine in Latin.0759

It is a terrible disorder, trisomy AT is one of the ways it can be caused, there are other ways.0763

If you look it up, there are other ways that spina bifida can result from other problems with the DNA.0769

Spina bifida, it varies in severity.0778

What they all have in common, in terms of what occurs,0782

is the spinal cord tissue is not completely encased within the body and within the vertebral column.0784

At the worst, babies who die young from spina bifida, part of their spinal cord tissue is actually emerging from the body.0792

You can imagine it would be tough to live that way.0801

Not only are you prone to infection, there is a lot of other health problems that happen.0804

One of my distant cousins which she was pregnant for the first time, the son that she gave birth to has spina bifida, died very early on.0808

That was very sad of course.0816

Now she has two children who were in high school, they are very healthy.0818

Her other two children were not born with that.0823

At the least, some people live with pretty life with the minor cases of spina bifida0826

where just a part of their spinal cord is not completely enclosed in the vertebral column.0832

They may be more vulnerable to certain spinal cord injuries than others but they can live a decent life.0839

Sex chromosome disorders are next.0846

These would not affect, just that 23rd pair.0849

You normally would get XX or XY, making a female or male.0853

Here are some examples of what can go wrong.0857

Turner syndrome is when you inherit an X but nothing else, there is a blank, whether it could be an X or another Y.0860

If you are wondering what happened here?0867

It depends, you could have had a sperm with an X chromosome fertilizing an egg that had no sex chromosome or the reverse,0869

you could have an sperm without a sex chromosome fertilizing an egg which have the X.0878

Turner syndrome, these are female but they do not develop fully as a normal developing female would, as she goes to puberty.0883

They are going to have underdeveloped sexual organs, underdeveloped breasts.0892

Their body proportions are going to be different than other people who do not have Turner syndrome.0896

A lot of the time these individuals are going to have trouble having children, they are going to be sterile.0902

When you imagine having these sex chromosomes, when you go to split them during meiosis,0906

a lot of your gametes are going to be missing things entirely.0912

Klinefelter syndrome is the flipside of what Turner syndrome is.0915

This is a male who does not develop as a male normally would.0919

Here you have a case where the egg had nondisjunction, or the egg had two X chromosomes and a Y sperm fertilized it.0923

Or you can have a sperm that is carrying XY, two sex chromosomes fertilizing an egg that is X.0930

These are males but since they have an extra X chromosome along with the normal XY,0937

they do not develop as males normally would.0943

They have underdeveloped sexual organs, a lot of times they are sterile.0946

They tend to have a more high pitched voice.0949

They do not develop as a normal male went through puberty.0952

Trisomy X, I have heard two different things about this.0957

I have looked in what seem to be reliable resources, regarding trisomy X.0960

This would result typically from an egg that has two X chromosomes and then an X sperm fertilizes it.0965

Triple X, the females, supposedly something around 1 and 1000 females have this.0973

I have read in some sources that females who have this sometimes do not even know.0981

There are no negative health results from this.0985

There are no negative side effects, they do not even know.0988

You may guess that these women are more likely to give birth or conceive of a child0992

that has a sexual chromosome disorder because some of their eggs are going to have two X chromosomes.0999

In effect, it is fertilized well, you can also have a child with that sexual chromosome problem.1005

But I have read that with other females, there are negative health effects with trisomy X, like severe health problems.1011

Which source was right?1019

I did some further investigation, apparently, in some females that is how it is.1021

In other females, it is the other way.1025

If that is the case where you have thousands and thousands of women who have trisomy X but some of them do not even know1028

and others have severe health problems due to that, it is safe to say that there are other chromosomes with others genotypes,1035

impacting whether or not these women have negative health consequences of having three X chromosomes.1042

That is my guess.1048

Super male, I came up with this term, pretty sure, I do not know that other books or resources are calling it this.1049

But this can happen, one way is a sperm with two Y chromosomes fertilizing an egg with an X.1056

What happens with these individuals?1064

They tend to be much larger, there are a lot more testosterone being produced in the body.1067

They tend to be, on average, a little bit more aggressive.1073

That is a generalization but let me put it this way.1077

If you were to survey, this would not be legal to actually do,1081

but if you were to somehow do a chromosomal test of all the man in the United States.1085

Let us say it is about 155,000,000 men, something like that.1092

You took all their chromosomes and looked at them.1099

Let us say the incidence of super male is 0.0001 of all the men.1104

That is the incidence, the percentage of men who have this.1114

Let us say we went to just prisons and did the same test on all of the inmates, all the male inmates.1118

In the prison, maybe 0.1.1126

What I’m trying to say here, I’m trying to say that if you are a super male, you are going to be going to jail, no.1130

I’m saying, there may be a correlation that men who have this super male condition1136

where they have two Y chromosomes when they only should have one.1142

Perhaps, they will be more prone to aggression, unchecked aggression that could get them in trouble, is what I'm saying.1145

Did I researched and find this out, no, I'm just putting this out there as a hypothetical scenario that may be true,1154

if we were to investigate this.1163

I'm sure there are plenty of individuals with the super male characteristic1165

that are able to deal with their aggression, that extra testosterone that they are producing.1168

Just putting it out there.1174

Miscarriage, blank Y why, there are lots of ways that a miscarriage can happen.1176

Presumably, 100 or even 1000 ways of miscarriage can happen.1182

Whether it is the pregnant woman getting in a car accident, the body just rejecting1186

the development of the baby because it was not developing properly, that can happen.1191

It could be that it is drug abuse that resulted in a miscarriage of the baby.1196

Whatever it might be, there are lots of ways that a miscarriage can happen.1199

This is one of them, you cannot be born without an X chromosome, it does not work.1202

There are too many genes on the X chromosome that are needed1208

for proper physiology and proper development of the human body.1211

If we had a Y sperm fertilize an egg with no sex chromosome, it is not going to work out.1216

The baby is not going to develop and will be miscarriage.1225

Pedigrees are visual depictions of an inheritance pattern for one gene in the family's history.1230

We are focusing was on one gene and how it goes through the generations.1236

We can actually use visuals to represent whether not an individual has this genotype or another genotype.1240

Males are going to be squares and females are circles.1247

This point here shows how we properly depict mating couples.1250

It is a square which is a male with a line connecting it to a female.1256

This does not necessarily mean that they are married because marriage is a social or religious convention, it is not biological.1260

If two people have made it in an offspring, whether or not they are married, this is how they are represented.1269

This means they have produced offspring.1274

Shows and represented by line that drops down from mating couples.1276

If we did this, these two had a girl.1280

I will s how you on the next few slides about how many children are represented with this line that has drop down from it.1284

We do not want to do this for instance, let me actually erase this and redo it.1292

We do not want to make this mistake if we are making a pedigree.1298

Here is the father, here is the mother, we do not want to do this.1301

That means that brother and sister having kids, no.1308

You will see on the next slide how you properly depict offspring from a couple.1310

That trait being traced is depicted by coloring in the individual, whatever we are tracing.1318

If it is a recessive trait, we are going to color all the individuals that have the homozygous recessive condition and not the others.1323

The opposite would be true if we are tracing a dominant trait.1330

Anyone who has the dominant allele, resulting in that particular trait or disorder,1333

they are going to be colored in the people who were recessive or not.1337

Depending on the trait, the colored individuals, dominant or recessive, as we will see on the next few slides.1341

Pedigree example 1, what is going on here.1348

We have grandparents here, there is the grandmother, she is colored in.1351

They have got two daughters and a son, this is how you properly depict the siblings.1356

This son had babies with this individual, two sons.1361

This grandchild, his second son here has the same characteristic as the mother.1366

Is this dominant? Is it recessive?1371

In this case, it has to be recessive.1375

This actually is an autosomal recessive trait.1379

Why, because it skipped a generation.1387

Here the grandmother has it, we will say she is homozygous recessive.1389

Now, because none of these individuals had it, you might think that they are all homozygous dominant.1397

That is not so, for this individual to have it, we know that this son here has to be heterozygous and also this mother heterozygous.1404

That is why this grandson here, the son of these two individuals is homozygous recessive.1413

Now, because this individual is definitely heterozygous, this son here of that mating pair,1419

what does this individual, this man has to be?1426

Actually I take it back, he does not have to be.1432

I was about to say he has to be this, no, not necessarily because whether or not he is this or this,1435

you can get the offspring, his son here, having the heterozygous condition.1443

We do not have enough information to say definitively whether or not he is homozygous dominant or heterozygous.1448

If we had more about this woman and the mating situation, maybe we can make a better guess.1454

What are these ladies, we know for a fact they have to be heterozygous.1463

We know they are not homozygous recessive because they will be colored in.1471

Why cannot they be homozygous dominate because they are always receiving recessive allele from mom.1475

We know that these sisters are also heterozygous like their brother.1481

It is autosomal or recessive because it skipped a generation.1485

If this was autosomal dominant, we would see the dominant allele1488

appears in every generation as it is passed on to the individuals who are also colored in.1491

Autosomal recessive, it is classic to see that skipping in generation there.1496

Pedigree example 2, a little bit different this time.1503

It turns out it is autosomal dominant.1509

Why, let us get it started.1518

Let us assume, I’m going to put a question mark because it is possible that he is homozygous dominant.1520

Let us just say that, that is the case there.1530

Because, this lady does not have the characteristic, she is homozygous recessive.1534

They also have the trait, they have at least one dominant allele.1542

This is starting to make sense, here we go.1547

This is all making sense, if this individual is recessive because clearly if it is autosomal dominant,1551

they will never color in all these individuals who have the dominant allele.1562

This granddaughter here has to be homozygous recessive.1566

The mother has to be able to pass on that recessive, she is heterozygous as well as the husband or the mating male, in that case.1571

If I erase this question mark and just say he is homozygous dominant, it is the same situation because still in this case, it makes sense that all of their offspring are going to be heterozygous.1585

Let me erase all of these and just play the little devil’s advocate about why this cannot be tracing a recessive.1598

Here is why there is no way the colored individuals are homozygous recessive.1607

The reason why is, if this individual is homozygous recessive and let us say she is heterozygous,1611

they also have to be recessive too, she will be recessive.1620

There is no way this daughter cannot be recessive.1624

She would have to be this.1630

There is no way that this particular pedigree is tracing a recessive trait.1633

It definitely is dominant, it turns out it is autosomal dominant.1639

Pedigree example 3, a little different here.1645

Here it is safe to say it is recessive because it is skipping generation 2.1648

A lot of pedigrees will do this, they will say that here is generation 1, here is generation 2, here is generation 3.1655

They will put little numbers next to the individuals like 1, 2, 3, 4.1664

We have names to call them, if we do not actually know their names.1668

In generation 1, we have one of the grandfathers with this condition, whatever it is.1672

No one in generation 2 has it, and then this grandson has it.1678

When you see that it is keeping a generation and it is affecting only males,1680

typically we are talking X- linked or sex-linked, is another term.1688

Recessive like hemophilia or red-green color blindness.1695

If we look at the family tree of Queen Victoria, you would see this.1701

You would actually see hemophilia pop up in her family.1706

If that is what is really being traced here, this woman is a carrier.1709

That is the only reason that this son was born with it.1714

Sometimes, you will see this.1717

Let me do the marker.1721

Sometimes, you will see carriers colored in half way, not always but sometimes.1724

I just want you to be aware that, it is sometimes an indicator that one of her alleles happens to be that form, the other one is not.1730

If you are wondering what is going on here.1738

He has it, she does not.1750

If this woman is a carrier, she inherited the defective allele from her dad.1753

Let us say, just for the sake of it that, this woman was not even carrying it.1760

But, this woman here, she does not have hemophilia but she has the potential to pass it on to her son.1765

Clearly, her son inherited that like dad.1772

This side of the family tree may have no incidence of that defective allele.1777

They could all be just completely healthy.1782

For instance, they would look like this.1784

When you get down to this guy, since he does not have it that would be his genotype.1788

The daughters here do not have it because they would have to have a dad who is a hemophiliac.1795

You would have to see the recessive allele there because in order for these girls to be a hemophiliac, they would have to have that.1801

I’m going to erase it because that is not the case.1808

This is tracing X-linked recessive, it just shown up in the males.1810

It is more likely that a male is a hemophiliac or has red and green color blindness1815

because just that one X chromosome defective is all it takes.1818

Environmental impact, gene expression oftentimes is influenced by the environment.1824

It is not just DNA, it is not just DNA doing what it does, the environment can impact what DNA is doing.1829

Twin studies have shown how powerful genetics can be.1835

The environment has an undeniable effect.1838

For instance, there have been twin studies where, let us say twins are given up for adoption and they went to different families.1841

Ideally, you would want twins to be adopted by the same family but this has happened before in human history.1846

When you study enough of these cases, and reunite these twins who have never seen each other,1853

oftentimes did not even know each other existed.1859

They will have similar mannerisms, similar idiosyncrasies about what they do and how they talk,1862

even though they are raised in completely different environments.1867

We will get a point to the DNA in that case.1871

They are sharing DNA that is impacting their brain chemistry and their development.1872

There are undeniable effects that DNA has.1877

Based on the fact they are in different environments, they are going to prefer different things.1880

They may have different accents because if you grow up in a certain part of the world,1885

you are going to have a certain accent compared to the other parts.1891

One of them may be slightly taller, one of them maybe a little bit more muscular.1894

There are undeniable effects that the environment has on how DNA expresses itself and how an organism develops overtime.1898

Here are just a few examples besides the twin studies.1905

Plant height, there is a study done in this species of plant that was growing along hillside.1908

Let us actually say it is a bigger mountain, not just hillside.1915

The plants that are up near the top of the mountain, it did not grow very tall.1917

Near the mountain, grew taller, further down, doing great.1922

They are all the same species, the environment is clearly having an impact on them.1931

We can test whether or not it is true.1937

Maybe it is just that the ones up here have genotypes that are more recessive and makes them grow shorter.1939

What they do is they took offspring from all of these plants and then1945

they plant them in a laboratory setting, all with the same altitude.1949

They all grew relatively the same height, showing that environment has a huge impact.1954

The reason why these ones were growing shorter, way up the mountain is not necessarily because of genetics,1959

it is because of the environmental conditions, or such.1965

Maybe there is less CO₂ available here, maybe the colder temperature, the intense winds,1968

all those things contributed to not being quite as ideal.1973

The conditions are more ideal down here.1979

Another example, skin and fur color.1982

With skin color, I think about getting tan, compared to the rest of my immediate family, I have the most trouble tanning.1987

That could be because I have slightly less dominant alleles than my brother does and my parents have.1993

Certainly, if I stayed indoors all day long for a few years, I did get pretty pale.2000

I would probably also have a vitamin D deficiency but skin color is certainly depending on the environment.2006

Not just because of UV radiation affecting your melanocytes and producing more melanin which makes you tan, it is not just that.2011

Things you eat can impact your skin color.2019

You may have heard that eating a lot of carrots which contain a lot of carotene can do that.2022

Carotene gets to positive and lower layers of the skin.2029

Especially, if you are a little more pale, it becomes more obvious.2032

You can see the orange coming through.2035

Fur colored animals gets impacted by the environment.2039

Some animals, during the winter months, their coat will actually turn white.2042

During the spring and summer, their coat becomes more of a grayish and brown.2046

That is great, in terms of camouflage.2051

That is an environmental impact on the organism.2053

Enzyme production and function, certainly related to the environment.2056

I have read that people who become vegetarians or vegans for long periods of time,2060

they will stop producing certain enzymes that are meant to breakdown animal tissue.2064

If you are not exposing your body to chicken, beef, whatever, why make the enzymes to break it down?2069

If you have not been exposed to those things, it would be a waste of energy.2075

When most people go back in ordering chicken sandwich after three years not having meat, they can get nauseous very easily.2078

I actually heard people vomiting from trying to jump into that meat dish a little too quickly.2086

You have to ease yourself back into it slowly.2091

Personality, this is not just with the twin situation.2095

Just personality in general has a lot to do with environment.2101

The things that you were exposed to overtime are going to influence your brain development.2104

Besides the human example, there are cases with dogs and cats.2109

You can now pay thousands of dollars to clone your dead cat or dog.2113

I am pretty sure, all you have to do is send in enough hair and make an extracted DNA.2119

For a fee, they will make you a clone version of your dead animal.2125

The problem with that is you are not going to get the same animal.2130

Yes, phyto number 2 will look very similar to phyto number 1, same DNA.2134

But there is no way that you can possibly replicate every environmental experience that animal had through out its life.2140

The new environment to phyto is going to lead to slightly different things going on in the brain.2147

Those experiences will not be the same as phyto number 1.2153

It would not be quite the same animal, even though it may look a lot like phyto 1.2157

Genetic engineering, this has a lot to do with the DNA and RNA lessons from before.2164

I’m taking some of that information and relating it to the genetics that2169

we have talked about recently with this lesson and the previous lesson.2174

Genetic transformation, inserting new genes in the organism and getting them to incorporate express those genes.2177

These new genes into an organism that coming from another organism.2183

A great example is when we do this to bacteria.2189

Here is a bacterium, let us give it a cell wall, made up of peptidoglycan.2192

Inside, we have got the single circular chromosome in the nuclear region.2200

Let us give it some ribosomes.2205

The reason why I’m bringing up bacteria with genetic transformation is2209

because it is easiest to genetically transform a single celled organism.2213

Thing about trying to insert new novel genes into me, I’m made of trillions of cells.2216

It would be very difficult and at this point in our scientific journey over the years,2221

it is currently not possible to do.2227

If you want to focus on just one specific tissue, yes, genetic transformation is possible with that.2229

A lot of genetic transformation studies that have been done with humans have resulted in bad things happening.2236

Unforeseen results, they are not intended, you have to be careful.2242

With a bacterial cell, it is much easier to do, it is one cell big.2246

It is much easier to get that new gene incorporated into the bacterium and expressed.2252

A great example of doing that is when you put in a plasmid.2257

That circular piece of DNA there, that plasmid is known as a vector.2261

It is a way to get new genes into an organism.2265

This is made with recombinant DNA which I will little talk more about in a second.2269

The way that you can view a plasmid to a bacterium is kind of like the utility belt for Batman.2273

If you are in the Batman story in the comic book, think about this cell without the plasma as being Bruce Wayne.2279

Normal guy Bruce Wayne existed; ignore the money, he is just a normal guy.2287

No superpowers, he can live a full life.2293

This bacterium has all it needs, in terms of what it really needs, in this chromosome here.2296

It is going to make its cell parts and get by and divide.2301

When you add a plasmid, the semi circular piece of DNA, it is like putting a utility belt.2305

It is like putting the suit on Bruce Wayne, he becomes batman.2312

Now, he has powers that he did not have before.2314

This plasmid can provide genes, novel genes, to the bacterium that allow it to resist antibiotics.2317

It can now make a flagellum, it can divide faster.2325

Whatever it might be, it can provide some kind of adaptation ability that they did not have before.2329

The amazing thing is a lot of bacteria, when they receive a plasmid, can easily copy it and send it to its bodies via conjugation.2335

That was covered in another lesson.2343

With this plasmid, restriction enzymes come into play.2347

Restriction enzymes, let me give you a sequence of DNA and you will see what I’m talking about.2351

Let us say here is a zoom in on the bases within the DNA double strand.2356

Here is the other side of it, complimentary, of course.2371

There you go, the restriction enzyme is cutting this up at a very specific site.2378

This zigzag here is the specific place that the enzyme is cutting the DNA.2384

If you are wondering, where do restriction enzymes come from?2390

Typically from bacterium, some bacteria have this amazing ability to make these enzymes that will cut up viral DNA,2392

when they are trying to invade the bacterial host cell.2399

That is a great thing to have.2402

If viruses come in, you can just slice up their DNA, prevent them from making copies of themselves, and destroying you.2404

We have taken enough of these restriction enzymes out of bacteria.2411

Now, we use these for awesome things.2414

Restriction enzyme, depending on what particular restriction enzyme you have, it cuts the DNA at very specific site.2417

Whatever this restriction enzyme is, it is cutting it always where there is this GCT CGA, always.2424

I will connect this in a second to gel electrophoresis, we will come back to that.2432

Recombinant DNA, an example would be this plasmid.2437

If we zoom in to this plasmid, this can be mostly bacterial DNA.2441

But, this piece right here is from another organism.2455

The reason why it is recombinant is, it is like you are recombining DNA from two different organisms into one.2458

Maybe this could be a human insulin gene.2463

We have done this, this is amazing.2472

You can crank out human insulin, the exact form of human insulin that diabetics need from bacteria.2474

It is like we are programming them to do abrading.2481

If you take out the healthy gene, the normal gene, that makes normal insulin,2484

and basically cut and paste it with restriction enzymes into this plasmid, it serves as a vector.2489

It is getting that DNA into the bacteria and you can stimulate the bacteria to2496

basically crank out this protein hormone that we can use for diabetics.2501

This form of insulin is way better than using bovine insulin which some people had allergic reactions and certain side effects from.2507

It is great, we actually can make insulin today doing that.2515

Gene cloning, if you do this with bacteria and then get bacteria to divide,2519

and they have them keep copying that plasma over and over in all their offspring bacteria through binary fission,2526

that is how you can clone genes.2532

You can make numerous copies of that gene over and over, for whatever you need from that gene.2534

Not only this, I have heard they do this with human growth hormone as well.2542

You can actually have a goat make a milk with human growth hormone in it.2547

How do you do that?2555

You can actually inject the human DNA into the nucleus of the goat.2556

You take an egg cell, enucleate it - meaning take the regular nucleus out.2562

Take that nucleus that has the human DNA in it and plant it in there.2567

Put that into the uterus of the goat.2573

Before you do that though, you have to coax that cell to develop as an embryo.2577

They need to do the implantation.2583

When that goat is born, it ends up producing milk.2584

You can get that human growth hormone in the milk they produce amazingly.2587

Polymerase chain reaction, PCR, this is a method using a machine that ends up making millions and millions of copies of DNA.2592

This is a brilliant, if you get DNA from a crime scene or you want to find out who is the daddy2602

like on the morning show, PCR is the way you do that.2608

You can take a little sample of DNA, prig this machine.2611

Over the course, I do not know exactly how long, but not very long.2615

You can end up making millions of copies.2619

The way does it is you have DNA polymerase, that is the enzyme that makes copies of DNA.2621

You have plenty of that in this machine.2634

It basically heats and cools, heats and cools, along with this you make various copies.2635

The heating and cooling, the heating actually splits apart those hydrogen bonds from the DNA.2641

The DNA polymerase goes on and makes copies.2648

Cooling will put the newly made strands together.2650

You heat it again, does a lot of it again, you cool it again.2654

You do that enough times, you can make millions of copies of DNA.2657

That is great because if you discover a little bit of DNA from a crime scene and that is all you have,2660

what if you accidentally damage them in the lab, there goes the evidence.2665

Having PCR allows you to make millions of copies of DNA, you have plenty.2668

It is an exact copy of what you have collected from that sample.2672

Gel electrophoresis is becoming a little bit more old fashion.2677

There are now machines that can do this way quicker and way easier.2681

This is a lab I do with my classes.2686

Here is a gel, an agarose gel, here you have what is known as wells in the gel.2690

Let me make this a little wider.2696

Since DNA is negatively charged, we are going to attach electrodes to this.2705

I will explain why that is in a second.2713

What you basically do is, you take a sample of DNA.2715

This actually goes along with finding out who committed a crime and who is your daddy kind of thing.2718

You take someone’s DNA, then you use restriction enzymes to cut up the DNA at various sites.2723

No two people on earth have the same junk DNA.2730

All that DNA that does not code for anything is random sequences of bases that you inherited2732

from the random sequences bases that are from your parents.2737

Even siblings have different junk DNA.2741

Even me and my brother, if we are to put the same three restriction enzymes amongst our DNA sample,2747

the way that they specifically get cut up are going to be a little bit different.2752

Because the exact sites in my chromosomes where I have GCT in the junk DNA regions are going to be a little bit different than my brothers.2756

Cutting them up at the places where we have eye color genes or genes related to red blood cell production,2764

millions or billions of people on earth have the same exact form.2770

We are talking about junk DNA that does not code for anything.2774

The exact site that the DNA get split up is different and that creates different lengths of DNA fragments.2777

You load the DNA fragments into these wells.2783

And then, when you turn on the current, here you have the negative charge and the positive charge.2786

Negative charges repel, like if it is negative and negative, negative and positive attract.2792

Since DNA is negatively charged, you turn this on and the DNA migrates along the well towards the positive end.2796

Let us say this simple, we get this banding pattern.2803

Let me actually do red.2807

Let us say this is the suspect or let us say this is the crime scene DNA.2811

This is suspect 1, 2, and 3.2817

We have applied all the same restriction enzymes to these different individuals in the samples.2821

Here is suspect 1, here is how the banding pattern ended up with him.2827

If you are wondering how these lines actually curve, what are they?2831

These are the different pieces of DNA.2834

Based on the length, they migrate different distances.2837

The ones that get this far, they are tinier.2841

The ones that are really big, they do not move as far.2843

It is like they drag more than in the gel as the electricity is applied.2847

These are really long fragments, these are tiny ones that were cut up in tinier bits.2850

Which means, there are more of these sites that is why they end up being tinier.2854

There is suspect 1, here is suspect 2.2859

I think suspect 2 did it.2868

These two are clearly a match.2876

That is just a short summary of what gel electrophoresis is.2879

Transgenic organisms, these are organisms that have multiple kinds of DNA together.2883

It is obviously not just their DNA.2891

One example of a transgenic organism would be that goat that I mentioned earlier,2893

that is producing milk that has human growth hormone in it.2899

Another example is, you can take e coli.2902

Let us say here is a little e coli cell with its peptidoglycan cell wall.2906

You can actually stimulate e coli to take up genes from a sea jelly that glows.2912

The sea jelly in the ocean, when enough UV radiation from the sun hits it, it actually glows green.2920

It looks fluorescent.2925

You can actually take that gene out of the sea jelly, have E coli take it up and express that glowing characteristic.2928

As long as you provide it the right kind of sugar source, the sugar ends up being a transcription factor2935

that allows the e coli to actually use the gene that allows the glowing.2942

There is actually a lab I talk about towards the end of this course, that gets you in more detail.2948

Transgenic organisms, overtime, I think we will see more and more of them.2953

Bioethics comes into play, in terms of how much are you willing to deal with, in terms of consequences with sort of playing god.2960

I know some scientists disagree with that term playing god but, some of my scientist friends,2968

they have the opinion that we should observe and study, and not intervene quite as much as some people want us to intervene.2974

There are some questions I come up, in terms of how far we go with making transgenic organisms.2981

The hope is that we can benefit society and benefit our health without getting too intrusive into what nature has created.2986

Thank you for watching