Hi there, my name is Issack Vaid and today I wanted to talk to you about inheritance.
What is inheritance?
Allow me to ask you a question.
You hear someone say, "He has his father's eyes," or, "She has her father's look."
Now, is there... is that some sort of big belief, or is there something truly there
on a biological level.
Did we just grow up believing that yes, we look like our parents and so, therefore, we
inherited our physical traits from them.
Or, is there something truly to it.
Now, what if my whole life I grew up believing that I am the son of Dwayne "The Rock" Johnson.
Now, if I sort of did a smolder, I think you could see the resemblance.
Now, there is something there when it comes to inheritance.
And, there's a lot to it, but first, before we go into it, let me introduce you to someone
very, very famous.
Someone very well known in the realm of inheritance and genetics that goes by the name of Gregor
Now, Gregor Mendel is a scientist.
He is the founder of genetics.
If it weren't for him, we wouldn't have the fundamental laws of genetics and what we know
about it today.
Now, knowing what we know about that, he and his studies have brought us closer to what
we know today.
An allele is a variance form of a given gene meaning it is one of two or more versions
of a known mutation at the same place on a chromosome.
A better way to get to know this is an allele is a pair that's part of... that is one pair
together that becomes what we call a genotype.
A genotype is, by definition, the genetic constitution of an individual organism.
Now, a genotype, in essence, is a genetic code that makes up our physical traits, should
Now the geno... along with the genotype we have what's known as a phenotype.
Now, a phenotype, by definition, is the set of observable characteristics of an individual
resulting from the interaction of its genotype with the environment.
Let's make that a little more clear.
A phenotype is what you see.
You see me?
I have dark brown eyes.
Now, you most likely...
most likely have dark brown eyes, or perhaps hazel, or blue, or any other color of the
Now, what I see there is your phenotype.
It's clear and given.
However, the genetic code behind that phenotype, what we call the genotype could be different.
Or, could be the same.
It could tell us you were one hundred percent most likely to have this phenotype.
Or, you were, let's say, twenty-five percent likely to have that phenotype and we don't
And, the way we can observe that is through what's called a Punnett Square!
A Punnett Square is a square diagram that is composed of a grid of usually four boxes
and is used to calculate and depict all the combinations of frequencies of the different
genotypes and phenotypes among the offspring of a cross in accordance with Mendelian Inheritance.
Now, what is Mendelian Inheritance?
That is the inheritance of characters specifically transmitted by genes in accord with Mendel's
We learned about Mendel, Gregor Mendel, who was the well-known scientist known as the
father of genetics.
That's all confusing.
No, no, no, it's not.
Don't worry about it.
Let's create a square diagram.
Just create on a piece of paper a square diagram.
Now you have, um, your parents genotype and you'll have your... you know there are alleles...
and you'll have your mother's genotype listed.
Now let's just say for the sake of ease, we'll say that your father's genotype was dominant
in having dark brown eyes and so is your mothers.
Your mother's genotype was also dominant in having dark brown eyes.
So as you can see when you fill in those squares that each square is a representation of twenty-five
Well, when you connect the dots of your father and your mother in each square, you can see
they're all the same and that would indicate... that's an indicator of... you were one hundred
percent likely to have dark brown eyes, because of their dominant genotype.
Now this obviously can be affected in many different ways.
Let's say your father had, you know, dark brown eyes and let's say your mother had light
blue eyes and they were both dominant.
There was no hidden recessive trait there.
Well, if that were the case you can see here that it would be fifty percent and fifty percent.
You're fifty percent likely to have dominant... to have brown eyes, and also fifty percent
likely to have blue eyes.
That said, that sort of gives us the whole gist and you know definitely play around with
the Punnett Square.
Now, of course, you would need your genetic code -- make up from your parents to really
understand what your physical traits were meant to be, however, if you don't have...
which that requires genetic tests and all, but if you don't have that you could still
play around with it on a phenotype basis.
And you can see that my mother has this eye color or this hair color, whichever trait
you want to focus on and sort of build that on a Punnett Square and see what was your
likelihood of possibly having, say, blonde hair versus dark brown hair or black hair.
There you go!
That's your breakdown of inheritance.
Thank you so much for watching and remember all genotype is beautiful, so definitely feel
proud of yourself there.
And, thanks for watching.
By Issack Vaid.