Sign In | Subscribe
Start learning today, and be successful in your academic & professional career. Start Today!
Loading video...
This is a quick preview of the lesson. For full access, please Log In or Sign up.
For more information, please see full course syllabus of Biology
  • Discussion

  • Download Lecture Slides

  • Table of Contents

  • Transcription

  • Related Books

Bookmark and Share

Start Learning Now

Our free lessons will get you started (Adobe Flash® required).
Get immediate access to our entire library.

Sign up for Educator.com

Membership Overview

  • Unlimited access to our entire library of courses.
  • Search and jump to exactly what you want to learn.
  • *Ask questions and get answers from the community and our teachers!
  • Practice questions with step-by-step solutions.
  • Download lesson files for programming and software training practice.
  • Track your course viewing progress.
  • Download lecture slides for taking notes.
  • Learn at your own pace... anytime, anywhere!

Laboratory Investigation VI: Inheritance Lab

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
  • Inheritance Lab Introduction 0:05
    • Purpose
    • Materials
    • Time
  • Explanation 2:03
  • Basic Procedure 5:03
  • Analysis 8:00
  • Inheritance Laws Connection 11:23
    • Law of Segregation
    • Law of Independent Assortment

Transcription: Laboratory Investigation VI: Inheritance Lab

Hi, welcome back to www.educator.com, this is the laboratory investigation 6, inheritance lab.0000

An introduction, first, purpose is to learn about the patterns of inheritance with sexual reproduction,0007

in terms of what genotypes/ phenotypes are passed on to offspring.0013

A review, genotypes is the specific combination of alleles or gene parts you inherited.0017

One allele from each parent for each gene and how they come together, 0023

and how they express themselves, ends up being phenotypes.0027

The phenotype is the physical manifestation of genotype.0032

Sometimes, environment does have an impact on phenotype, on how the genotype is expressed.0037

This lab, we are going to be doing some coin flipping to represent what genotype is being inherited and0043

that will give a resulting phenotype, some kind of a look in the offspring.0048

Materials are two coins, quarters, pennies.0053

If you are not in America, any coins will do.0055

The point is to have one side is different from the other, tails and heads.0058

One lab partner, it is much more fun to do this where one person, each has a coin, 0063

and together flipping the coins is replicating which alleles in the sperm and the egg is going to be passed on to form the offspring.0069

If two girls are doing this, for the purpose of this, one of them would have to represent the male.0079

If two boys are doing this, one of them has to represent the female.0085

Because, in terms of which partner in this sexual reproduction simulation determines the sex of the baby,0089

we do have the differentiation and you will see on the next slide why that is.0097

You do have to list out genotype/ phenotype combos, in terms of what is possible to be inherited 0101

when we flip these coins, what is that all mean.0107

I will give you some examples of what can be there.0110

There are lots of different versions of this lab, it is very commonly done in biology classrooms.0114

The time required, about 30 minutes rather.0120

Explanation, assume that you and your partner are both heterozygous for every genotype in your body.0124

The reason why it is important is because the Punnet squares will look like this.0130

If you remember, Punnet squares are meant to be a visual representation of the probability of inheritance0134

for these allelic combinations, of what is going to end up as your genotype.0143

If both individuals are heterozygous, mom and dad, here is the possible genotype that you end up getting in the F1.0148

If these are the P generation, and this is that F generation.0163

You could see that there is 1 – 2 – 1 genotypic ratio.0169

Depending on the specific trait we are talking about, there could be a 3 -1 genotypic ratio,0178

where all three of these look the same.0184

And then, there will be some other scenarios where this, this, and this all are actually different,0187

there will be three different phenotype.0194

I will explain it on the next slide.0196

For each trait, you and your partner will flip the coin.0198

If it lands on heads, the allele is dominant for that individual, in terms of what they are passing on.0201

If both people flip heads, you are getting this.0205

If one of you flips heads and one of the flips tails, it will be that.0213

If it goes the other way, where you both flip tails and heads but the opposite happens, it ends up being the same genotype.0218

That is why there is a 50% chance of that happening.0225

Heterozygous is going to happen, statistically 50% of the time.0228

If you both flip tails, you are going to get that homozygous recessive case.0232

Before you get started with all these different traits on the next slide, you got to determine what the sex of the baby is going to be.0240

This has to do with what sex chromosomes actually in the sperm that fertilizes the egg.0246

If we do a little mini Punnet for how a mom and a dad are contributing the sex chromosomes to the baby, females are X sex.0251

Every egg should have just an X chromosome.0262

But with sperm, half the sperm would have the X and half the sperm would have the Y.0265

Whichever partner in the scenario is representing the man, that particular person flips it once.0272

You can see that it has 50% female, 50% male.0281

We are going to flip it once, it is basically flipping one or that, it is going to be that or that.0286

They flip once, if it is heads then that mean an X chromosome fertilize the egg.0291

If it is tails, it means that a Y chromosome fertilize the egg, and it is a male baby.0297

The basic procedure, here is an example of the traits that we are going to be flipping for.0305

Let us say for hairstyle, there is curly as a phenotype, wavy as a phenotype, and straight as a phenotype.0310

Those three different phenotypes and the genotype look like this.0325

If you both flip heads, curly hair.0334

If you each flip the opposite, wavy hair.0340

If you both flip tails, straight hair.0343

That is an example where you actually have a 1-2-1 ratio of phenotype, in addition to genotype there are three actual combinations.0345

Here is a case where you do not have that.0351

With widow’s peak, let me use w for this particular one.0353

You can get W, that is homozygous dominant.0357

You get heterozygous and you can get homozygous recessive.0361

It turns out that, both of these equals a widow’s peak, having that particular trait.0365

Occasionally, a widow’s peak, if you look at the hairline, it is coming to a point here 0375

like a little triangle in the middle, that is a widow's peak.0381

This homozygous recessive, no widow’s peak.0385

If you inherit the dominant allele, it will look like mine where it is straight.0388

Here is an example where it actually use a 3-1 ratio, there is 75% chance of getting a widow's peak, 0395

only a 25% chance of flipping the homozygous recessive traits.0403

Face shape, it could be round or more squared off, your size, large, medium, small.0410

You have three there, nose large, medium, small.0420

Cleft chin can be something like widow's peak where, homozygous dominant heterozygous 0426

give you that dimples, something called butt chin.0431

I have a slight one but it is hard to see because of my goatee.0435

Freckles is another one where just one dominant allele can give it to you.0439

That could be where there is only two options.0444

Freckles with at least one dominant allele or no freckles, it could be the same case.0447

The actual lab I hand out has, I would say twice as many as this.0452

It is fun, students doing these coin flips and some are moaning like, our kid got this.0458

Some of them will say our kid is ugly.0463

I told them you should be proud of your child because they came from you and you will love them, regardless.0467

We have some fun doing this, at the end they draw a picture of what the child is going to look like.0474

They named it, it is pretty fun.0478

Analysis, after doing this coin flip and saying this is what is inherited, how realistic is this lab activity?0482

It certainly has it limitations, is it true that there are just three hairstyles, curly, wavy, straight?0490

No, there is actually more than that.0500

There is probably multiple genes influencing exactly how your hair curls or does not curl.0502

In terms of hair color, definitely more than one gene.0510

The shape of your face, certainly lot of genes.0513

There are a lot of skull bones that are formed to make the exact shape and slope of your face, the size of your jaw, 0516

the angles of your face, the cranium size, everything, all those little minutia that we do not even notice.0524

There are genes influencing that.0533

This is most simplistic of a lab, it is designed to be fun.0535

It is designed to bring the concept of a Punnet square into a more real format that students can grasp.0539

Most of the traits mentioned in this lab are actually affected by more than one gene, polygenetic inheritance.0547

That is when more than one gene influences a single trait.0555

By the way, there are 25,000 to 30,000 genes that coffer proteins in the human genome.0559

Some sources say there are at least 20,000, I have heard up to 30,000.0565

This is the approximation I like to go with.0570

This is by the way, what is coding for proteins, in terms of what we know for fact is producing products in the body.0573

There is plenty more genes than that and we call that junk DNA.0585

It could be that some image of that junk DNA that seems useless 0590

which is the vast majority of genetic material is actually doing things that we have not noticed yet.0592

More regulatory or promoting, kind of promoting some factors, promoting that gene is in red, 0597

do not read that gene, at different times during an individual's life.0608

A lot of it is still up in the air, in terms of what we know about DNA.0613

I think we are just scratching the surface but this is my best approximation for how many genes are actually making proteins.0620

Some proteins are visible like the proteins that affect your hair color or affect your skin color, or affect how tall you are.0628

You can actually see the protein, that is why I’m saying visible meaning the effects of the proteins are visible 0638

because proteins themselves are microscopic.0644

Whether it is enzymes or structural proteins, globular proteins, some of them do impact traits that you can see on the surface.0647

Even their physical manifestations are not visible, it is stuff going on inside the body, it does not mean that it is not there.0658

I like this image, it is taking one of those condensed eukaryotic chromosomes and taking out the DNA from it.0666

You can see that double stranded molecule, the double helix.0672

Bringing us back to the concept of exons and introns related to RNA processing.0677

Inheritance laws connection, the point of the lab is illustrate the two main laws of Mendelian inheritance.0685

Law segregation states that, when you are making pollen, eggs, sperm, whatever it might be,0692

and you have got homologous chromosomes lined up during metaphase 1 of meiosis.0700

The law of segregation says, these are going to segregate, meaning those gene parts are going to be split up.0709

Half the amount of DNA is in sperm and egg, in each one of those cells.0716

That is where we get that term haploid from, rather than diploid.0720

Once we get to metaphase 2 and anaphase 2, we end up getting these in the sperm and egg.0724

That is the law of segregation, where we are splitting up that information.0740

This corresponds to having like, maybe this is from dad and this is from mom.0743

Since it is duplicated, it would be like that and like that.0750

By the time you get to here, it will be like that.0753

This particular sperm, this particular egg, you have the dominant allele on that chromosome, the recessive on that.0757

That is the law of segregation related to the genotype you see in a Punnet square.0765

The law of independence meaning all the difference genes, the ones that affects height, 0770

the ones that affect skin color, hair color, eye color.0777

The one that affect personality, that ones that affects how you heal.0780

The ones that affect metabolism, whatever it might be.0785

They are inherited independently, they do not have an impact on one another.0788

Just because you flip the coins and end up getting dimples, it does not mean you are going to get freckles.0791

Just because you flip and get freckles, it does not mean you are going to get widow’s peak.0796

It does not mean you would not get a widow’s peak.0799

The exception to this is the concept of linked genes.0801

Mendel did know about that at that time, there are cases where certain genes are inherited together and those are called linked genes.0813

But other than that, independent assortment is for real and it helps us understand the advantages of inheritance.0821

That is great, in terms of the amount of variety that we have in our species.0829

Thank you for watching www.educator.com.0834