00:01
Okay, this question covers the topic of mendelian inheritance, specifically the type of ex -linked dominant traits.
00:12
Okay, so let's define what is an ex -linked dominant trade.
00:24
First, when they say that it is ex -linked, remember that the other type is autosomal, okay, but this time it is not autosomal, it is ex -linked.
00:33
You have autosomal and sex chromosomes okay you have autosomals and sex chromosomes from chromosome 1 to 22 because you have 23 pairs of chromosomes remember they are autosomal and the last pair is sex chromosome okay let's just focus on this on this pair.
01:08
It can be, it is a pair, remember, and this pair can be either x, x, x, or x, y.
01:13
Okay, x, x, as you, as you know, is for a female, and x, y, it is for a male.
01:24
When they say that the trade is x -linked, it is talking about this, a chromosomal pair, okay, about x, x, or x, or, well, of the x chromosome, specifically.
01:37
Okay? so, and when they talk about dominant, okay, the other type is recessive.
01:49
Okay, remember that for a genotype, for one trait, for one gene, you have a genotype that is made of two alleles.
01:58
One coming from the mother and one coming from the father, okay? so you have two types of alleles, one dominant and one recessive.
02:09
The dominant is always expressed in a capital letter, for example, a, and a aggressive allele is expressed in a lowercase letter, for example, a.
02:24
Whenever the dominant allele is present, then the dominant trade is going to be expressed.
02:30
For example, let's suppose in this case, in this case of a and a, the dominant trade or the dominant the lille calls for black eyes okay and the recessive for white eyes if the a or the dominant trade is present in the genotype then the person will have black eyes but when the gen the dominant the lil is absent it means there is there are two a or recessive two recessive alleles then the white or the excessive trade is going to be expressed in this case the white eyes okay so remember that xx is for females and xy is for males.
03:15
So, x -linked dominant.
03:19
In case of males, as they have only one x chromosome, then when they have this x chromosome, like mutant, it means it has the mutation that we're talking about, then the person is going to, the male is going to express the disease.
03:39
It means it does not require another chromosome affected...