Hair color can change

- A middle school student from the US

May 22, 2018

Hair and eye color are mostly determined by our genes. But it’s not just by the genes we have, but also by whether those genes are turned on or turned off. And since genes can turn on and off throughout our lives, this means your hair color can change!

The most important genes here are ones that make pigment, which is what gives hair its color.

The name of this pigment is melanin. It’s the same pigment that gives skin its color!

What happens when we age?

When we age our hair eventually turns gray and sometimes white. This occurs because our melanocytes (the cells that make melanin) wear out.

When melanocytes wear out, they aren’t as good at passing the pigment on to the cells that make hair. If this pigment isn’t passed on correctly, it doesn’t get included in the new hair. A hair that gets only a little pigment is gray, while a hair that doesn’t get any pigment is white.

Three equally represented phenotypes

This is for creative writing, so feel free to take any liberties in assuming the theoretical world's other aspects!

- A high school student from Texas

May 7, 2018

 

In a dominance series, version A of the gene is dominant to version B, which is in turn dominant to version C. We can represent this as A > B > C.

For our unicorns, average horns are dominant to big horns. Big horns are dominant to curved horns. Finally, curved horns are recessive, completing our dominance series A > B > C.

When we have three alleles, we have six possible genotypes. For our unicorns, they are as follows:

Blond hair, blue eyes

-  A curious high school student

May 7, 2018

 

Yes, it is! You might also notice that people with brown hair typically have brown eyes. Skin color also often fits in this trend: people with lighter hair and skin often have light eyes. And people with darker hair and skin usually have dark eyes.

The color of our hair, skin, and eyes is determined by the same thing: the amount of pigment they have. The pigment that causes dark hair, skin, and eyes is called melanin.

Fragile X chances

- A curious adult from the US
 
May 7, 2018
 
Tricky question! Fragile X is a very complicated genetic condition. In short, in this case, the chance of having a male child with Fragile X may be somewhere between 5-19%, and a female child with Fragile X is much, much, much lower. But let’s dig deeper into that. 
 
Chromosomes are like libraries for our genes. 
We have thousands of genes that instruct our bodies on how they should develop, determining things like hair color, eye color, and body parts. These genes are organized into chunks called chromosomes. 
 
The X chromosome is one of two sex chromosomes. Sex chromosomes help determine whether someone has the reproductive body parts of a boy or a girl. Typically, girls have two X chromosomes, and boys have an X and a Y chromosome. 
 

Golden State Killer suspect tracked down through familial DNA

April 28, 2018
 
After more than 40 years, the Golden State Killer is finally behind bars. Joseph James DeAngelo is accused of 12 murders, over 50 rapes, and more than 100 burglaries. His capture is being credited to -- or blamed on -- his DNA. But police didn’t originally match the DNA at the crime scene to him. Decades after his crimes, police matched DNA that family members put in a public database.
 

Genetics of Anxiety

– A middle school student from WA

April 19, 2018

 

The short answer to your question is “to some extent, yes.” When we think about traits that are determined by our genes, often the first things that come to mind are hair and eye color. But our genes don’t just shape our physical traits: they also influence our emotional ones.

Bisexual

– An undergraduate student from California

April 18, 2018

 

Only Colorblind Person in My Family

-A high school student from the UK

March 23, 2018

 

The quick answer is that you most likely got your colorblindness from your mom. And she got the DNA for colorblindness from her mom. And so on.

Here are the possible combinations for a biological female:

Here, the X chromosome that can cause colorblindness is shown in red. As you can see, it is only when both X’s are red that she is colorblind.

The same is not true for biological males.

As biological males only have one copy of the X chromosome, they only need one colorblind X to be colorblind. Because of this, men are much more likely to be colorblind than women.

What recombination is and why it matters

-A curious adult from Texas

February 5, 2018

Recombination is a big reason we are all unique. It is also a way to keep our DNA from building up too many mistakes. Recombination can repair broken DNA.

That is the why. To get to the how, we are going to need to talk a bit about our DNA and how it is organized.

DNA is Packaged in Chromosomes

Your DNA has the instructions for making you. If we stretched out those instructions, they’d be over 6 feet long.

Recombination goes something like this:

(yourgenome)

In this image, the chromosomes are shown as X’s. The darker blue-green one is one chromosome in the pair and the light blue is the other. (You can ignore the a’s, b’s, and c’s.)

Let’s go over how recombination resulted in the chromosome 1 result.

Let’s say these are mom and dad’s chromosome 1’s:

Dad has a blue and an orange one. I have drawn the two mom’s in gray because we won’t be following those. We will only look at the shared DNA from dad.

Now let’s see what happens when dad’s DNA is passed down to the half-brother and the half-sister:

reprogramming DNA in somatic cell nuclear transfer

-A high school student from Tennessee

January 29, 2018

The really short answer is that scientists don’t change the DNA itself. The egg has the stuff it needs to read the parts of the DNA instructions necessary to make an embryo.

The egg can “open up” or “unroll” the parts of the DNA needed to get the egg to start on the journey towards developing into a baby. To do this, it uses something in the egg called “pioneer factors.”

Different Cells Use Different Parts of the Same DNA

DNA is Rolled Up in Proteins

Obviously, our genes aren’t paper wrapped around a stick. However, the truth isn’t too far off. The DNA that makes up a gene is wrapped around individual proteins called histones.

Remember the individual instructions in the DNA called genes? Well, they don’t do anything as DNA.

Instead the instructions are read by the cell and ultimately turned into proteins. It is these proteins that do the work in a cell.

Histones are one of these proteins. They are the “spool” around which DNA is wound.

However, some transcription factors, the “pioneer factors” can actually open up the DNA.  Yes, scientists really call them pioneer factors.

Like the pioneers of the old west, they find where they need to go all on their own, settle down, and other factors come to them. Pioneer factors push the histones out of the way so the other proteins can read the DNA.

Eggs are Full of Pioneer Factors

Before eggs are fertilized, their DNA isn’t being read. Mom gave the egg all the proteins it would need to start going from one cell to a full organism.

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