FAQs and goodbye...for now...

After a lot of debriefing, I found myself growing bored of the whole genetics thing. SO I move on to new wonders. But before I do, Im going to answer some FAQs.

How did you become interested in Genetics?
The unlimited (and yet limited) possibilities in genetics! You can create virtually anything with any trait, much like those Rebops.

Can two dominant phenotypic parents produce a recessive off spring?
Yes! As long as both parents are heterozygous, they still carry the recessive trait, which  (with a 25% chance) can reappear in offspring.

Are you cool?
Yes.

Are you making up questions now?
Yes.

So long, my friends. a new adventure is awaiting me!

Dr. Freddie Stein

Dihybrid squares

In order to find the phenotypes of two traits at the same time, you must use

DIHYBRID Punnet squares. 

You first star with two traits, say eye color and hair color:

Hh and Ee

And then you put the two traits together: 

HhEe

From this, you can distribute all the possibilities of traits: 

And create a 16-box Punnet square, distributing the trait pairs like you would in a regular punnet square:

This shows all the possible trait combinations for two heterozygous parents. 

In a rush to type this before my mother finds out,

Dr. Freddie Stein

My Creation.

Rebops, simple creatures that have many traits but simple allele pairs! ALL CONTROLLED BY ME. MUAHA.

In all seriousness, I will be controlling the genes for my rebops by randomly choosing the alleles on the chromosomes produced by Momma Rebop and Dad Rebop. 

Say you have your Mom Rebop chromosomes, which carry genetic information, and your Dad chromosomes: 

When those Rebops breed, they match up their chromosomes individually: 

Each of these pairs represents a different trait or gene,  so one pair could represent EE or Gg or Tt for any trait. 

The traits that I will study in my little rebops are the number of body segments, the color of nose, how many antannae, the shape of the tail (curly or straight), color of legs, the number of eyes, and the number and color of humps. All of these traits are either dominant, recessive, incomplete or codominant.

The results for my Chromosome pairs are Dd, Tt, Qq, ll, aa, EE, Mm, which determine the traits listed here: 

So the phenotypes of my first Rebop will be:

-Three body segments

-No antennae

-Orange nose

-Two eyes

-Two green humps

-Curly tail

- Red legs

HERE HE IS: 

Hes so cute. 

This experiment is an excellent way of showing how chromosomes carry alleles and code for the phenotypes of many different traits. 

Speaking of multiple traits, there's a punnet square for that too. 

Youll just have to come back later. 

Dr. Freddie Stein

Data is always good.

The results are in from "breeding" my pennies 100 times. Or flipping them 100 times...

Homozygous dominant (HH)- 27 offspring

Heterozygous (Hh)- 47 offspring

Homozygous recessive- 26 offspring

If we compare these results to the results of the Punnett square: 

The results are practically identical! I never should have doubted the Great Mendel's theories. 

However.

What if the parents are homozygous? 

Lucky you, I already have that data, if one of the parents was homozygous dominant for the brown fur color. 

    F     F

F FF   FF

f  Ff    Ff 

Almost identical again. And YOU were beginning to question the Great Mendel's theories!

These results prove how the way traits are distributed are very similar to their probabilites of actually appearing in the phenotype and genotype. Probability of obtaining a ceratin trait is pretty much accurate using just a Punett square!

Making plans,

Dr. Freddie Stein

Freddie Goes Experimental

While Gregor Mendel is all great, i find myself greater sometimes. That is why Ive decided to test some things out for myself, with the most advanced technology only found in the depths of my room.

The Penny.

The most faithful form of experimental probability, with a 50% chance of landing heads and 50% chance of landing tails. Also a quick, easy way to test if outcomes of traits really are accurate if one only uses Punnett squares. 

I'm going to think of my genetic testing as the fur color of squirrels I caught nearly half an hour ago, planning to breed them for my experiment, when my mother found the cage and asked, very loudly, for me to let them go. The squirrels had a brown fur color and a gray fur color, brown being the dominant factor.

Because the pennies (soon to be squirrel parents) have two sides, and there is an equal chance of getting either, the parents must have a heterozygous fur color, which would be the phenotype brown.

This Punnett square will appear like this: 

     F     f

F  FF   Ff

f   Ff    ff

This shows that 25% of the offspring will have homozygous dominant fur, which will appear as brown, 50% will be heterozygous and will appear as brown, and 25% will be homozygous recessive, or gray. 

And to specify what allele goes to what side of the penny: 

Heads: F, or dominant

Tails: f, or recessive.

Off to collect data, 

Dr. Freddie Stein

Dihybrid Punnet Squares

Say you don't want to go through the hassle of making completely different punnet squares for each trait on your Rebop. THERE IS A SOLUTION.

DIHYBRID PUNNET SQUARES.

You have two traits, say hair color and eye color, and each parent is heterozygous for both, whose phenotype is brown hair and brown eyes. Recessive traits are blonde hair and blue eyes.

Both parents have two separate traits, hair color and eye color:
Hh and Ee
Because we will be dealing with dividing these traits together, they get squished into one trait:
HhEe

These are then distributed into all the genotype possibilities:

Each of these are lined up on the punnet square, much like the single-trait punnet squares, except far bigger:

This shows all the possible phenotypes for both traits at the same time.
Thats all for now,
Dr. Freddie Stein

Co-dominance and Incomplete Dominance

I know youre on the edge of you seats. When does the "dominant always appears over recessive" rule not apply?

Im glad you sort-of asked.

Co-dominance and Incomplete dominance are similar in the way that both traits influence the phenotype of an offspring, but different in the way where Co-Dominance has both traits appear and Incomplete dominance allows the traits to blend.

Incomplete dominance:
Say you have a flower that has three different phenotypes, white, blue and purple.
Lets say red is recessive, or ww, and blue is dominant, or WW.
The punnet square of heterozygous parents here would look like this:

The purple flowers, or the Ww heterozygous flowers, blended the trait from the dominant blue trait and the recessive red trait to make purple!

Co-dominance:
Unlike incomplete dominance, co-dominance has both traits appear, so instead of the flowers blending color, they both are shown:

Instead of the traits blending together to make q new color, they both appear on the flower.

F2 Generation Outcomes

So whatever happened in the F2 generation?

As we know from our first punett square, each of the offspring had the genotype Tt, which would appear as tall because the T masks the t.

Mendel then allowed this offspring to self-pollinate, or have the offspring's anthers (male organ) to ferilize the stigma (female organ). This would cause the same genotype to be mixed:

      T    t
T  TT  Tt
t   Tt    tt

WOAH. The four offspring have quite a mix of genotypes, including the homozygous (the same type of allele) dominant, the homozygous recessive, and the heterozygous (one of each type of allele). The same rule applies though, the dominant trait (at least in this case) will always show over the recessive. So, if you look at all of your options from the offspring, they are the following:

TT- Homozygous dominant,, will appear as tall
Tt- Heterozygous, will appear as tall
Tt- Heterozygous, will appear as tall
tt- Homozygous recessive, will appear as short.

This explains how the second generation of Mendel's appeared 75% with the dominant trait, tall, and 25% the recessive trait, and sums up the basics of genetics that Mendel found.

Gotta go. More basics tomorrow!

I've returned. Under my blankets and pillows. Judging by the stuffiness of this hiding spot, I dont have much oxygen to spare. So I'll make this quick.

Where was I.

AH Punett squares, yes.

The parents, as you may recall, were tall and short. Say you have an offspring recipe, and in order to make it you need two parts tall and two parts short. These "parts" are what we call alleles, the parts of a gene, which are given by the parents of the offspring.

With Punnet squares, this arangement of alleles would look like this, where tall is represented by a T and short is represented by a t:

Tall Plant: TT
Short Plant: tt

The tall plant in this case is dominant, or greater than the short plant, because it has two T's that will mask the other t's. The short plant is recessive, or less than the taller one.

In this case, the punett square would look like this:

   T    T
t  Tt   Tt 
t  Tt   Tt

Now, all the alleles are arranged into new genes: Tt, the genotype (the genetic makeup of the offspring).

But what does that mean? We couldn't possibly have a mixing of  alleles, BOTH traits would appear!

Not necessarily. While it is possible in some cases (stay tuned) it isn't in this case.

Because the T is still dominant and will mask the t, the T or tall trait will appear. This is why in Mendel's first generation, ALL the plants appeared as tall, or the phenotype (the trait that actually appears).

Well, now I'm absolutely exhausted. I'll tell of the F2 generation tomorrow.

The Basics of What Mendel Found

While almost as genius as I, Mendel found the following after cross-pollinating a short pea plant with a tall one (which I did not do), or the  P1 Generation. All of these parent's offspring had the same dominant (or trait that masks another) trait.

After finding this, Mendel then allowed the F1 generation, or the first generation, to self-pollinate. This resulted in the F2 generation, or the second generation, to produce 75% of the plants to be tall, and 25% to be short.
How curious, one might say.
WRONG.
Its quite simple, actually.
You see, punnet squares (or as I like to call them, party squares. They're just so much fun!) show how this mix of heights is possible.
Er...perhaps ill explain at another time. Mum is yelling for me to "Quit that typing racket." and "I know youre still awake, Jacob." 
Bye.

Gregor Mendel, the ORIGINAL father of Genetics. (a.k.a. my hero)

Gregor Mendel, the father of genetics and my ultimate hero when it comes to genetic science. Studying pea plants, Mendel found the laws of dominance, segregation, and independent assortment all through the height, pea shape, pea color, flower color, and many more traits of the plants. The basics of his findings inspired (and helped) scientists, such as my handsome self, know the basics of heredity. Him and I couldve been best friends. Curse my being born in this era.