Sex linked Genetic diagrams

Summary

This educational video script delves into sex-linked disorders, focusing on how they are inherited and calculated using a Punnett square. It explains the role of sex chromosomes in determining biological sex and susceptibility to disorders. The script uses examples like red-green color blindness and hemophilia to illustrate X-linked recessive disorders, highlighting the difference in inheritance patterns between males and females. It also clarifies the distinction between genotype and phenotype, emphasizing the importance of understanding these concepts for grasping sex-linked inheritance.

Takeaways

• 🧬 Sex-linked disorders are genetic conditions that are passed down through the sex chromosomes, specifically the X chromosome.
• 🔍 Humans have 23 pairs of chromosomes, with the 23rd pair being the sex chromosomes, which include the X and Y chromosomes.
• 🚺 Females have two X chromosomes (XX), making them less susceptible to sex-linked disorders, as one X chromosome can compensate for the other in case of damage.
• 🚹 Males have one X and one Y chromosome (XY), which makes them more vulnerable to sex-linked disorders since they have only one X chromosome to carry disease alleles.
• 🟥 Red-green color blindness is an example of a common sex-linked recessive disorder, affecting the ability to distinguish certain colors.
• 🔄 Inheritance patterns of sex-linked disorders can be visualized using Punnett squares, which help predict the likelihood of offspring inheriting the condition.
• 👨‍👩‍👧‍👦 A carrier mother can pass on a sex-linked disorder to her children, with sons being more likely to express the disorder due to having only one X chromosome.
• 🩸 Hemophilia is another example of a sex-linked disorder, typically affecting males and being carried by females as they have two X chromosomes.
• 🧬 The script explains how to calculate the probability of offspring inheriting sex-linked disorders using genetic crosses and Punnett squares.
• 📝 When explaining sex-linked inheritance, it's important to describe the genotypes of the parents and how the inheritance of one allele from each parent affects the offspring.

Q & A

What are the two types of sex chromosomes in humans?

The two types of sex chromosomes in humans are the X chromosome and the Y chromosome.

How do females and males differ in their sex chromosome composition?

Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

What is the significance of having two X chromosomes in females in terms of disease susceptibility?

Females are less susceptible to X-linked disorders because if one X chromosome is damaged, the other can compensate and help fix the problem.

Why are males more prone to X-linked disorders compared to females?

Males are more prone to X-linked disorders because they have only one X chromosome, and if it carries a recessive disease-causing allele, they will express the disorder since they have no second X chromosome to mask it.

What is the difference between autosomes and sex chromosomes?

Autosomes are the first 22 pairs of chromosomes that are not involved in sex determination, while sex chromosomes (gonosomes) are the 23rd pair, which include the X and Y chromosomes that determine biological sex.

What is a common example of an X-linked recessive disorder mentioned in the script?

A common example of an X-linked recessive disorder mentioned is red-green color blindness.

How is the inheritance of X-linked disorders represented in a Punnett square?

In a Punnett square for X-linked disorders, the alleles are represented as superscripts on the X chromosome, with a dominant allele (usually a capital letter) and a recessive allele (usually a lowercase letter).

What is the significance of the term 'carrier' in the context of X-linked disorders?

A 'carrier' refers to an individual, typically female, who has one normal allele and one allele for an X-linked recessive disorder. They do not express the disorder but can pass the disorder allele to their offspring.

How do you determine the probability of offspring inheriting an X-linked disorder from a Punnett square?

You determine the probability by looking at the genotypes resulting from the cross and calculating the percentage of offspring that receive the recessive allele on their single X chromosome (males) or both X chromosomes (females).

Why is it important to specify the sex when describing the phenotypes in a sex-linked inheritance scenario?

Specifying the sex is important because the phenotype of an individual with a sex-linked disorder can differ between males and females due to the different composition of their sex chromosomes.

What is the difference between genotype and phenotype in the context of sex-linked disorders?

Genotype refers to the specific set of alleles an individual carries for a gene, while phenotype refers to the observable characteristics or traits that result from the interaction of those alleles with the individual's environment.

Outlines

00:00

🧬 Introduction to Sex-Linked Disorders

This paragraph introduces the topic of sex-linked disorders, focusing on how they are inherited and calculated using a Punnett square. It explains the role of sex chromosomes, the X and Y, in determining biological sex and how autosomes differ from them. The paragraph emphasizes the importance of understanding chromosome structure, particularly the X and Y chromosomes, and their combinations in males and females. It also touches on the concept of females being less susceptible to certain disorders due to having two X chromosomes, which can compensate for a damaged one, unlike males who have only one X chromosome and are thus more vulnerable to X-linked disorders.

05:00

👨‍👩‍👧‍👦 Inheritance Patterns and Examples

The second paragraph delves into the inheritance patterns of sex-linked disorders, using red-green color blindness as an example. It describes how this condition is a recessive disorder carried on the X chromosome and represented with a lowercase 'r' as a superscript. The paragraph explains the genetic cross of an unaffected father and a carrier mother, detailing the possible outcomes for their offspring. It clarifies that unaffected sons inherit a capital 'R' from their mother, while daughters can be either unaffected or carriers, depending on whether they inherit the small 'r' from their mother. The paragraph also discusses how to represent these genetic outcomes visually and emphasizes the importance of knowing the genotypes and phenotypes for understanding sex-linked inheritance.

10:02

🧵 Calculating Sex-Linked Inheritance: Hemophilia

This paragraph shifts the focus to another common sex-linked disorder, hemophilia, to demonstrate how to calculate sex-linked inheritance. It outlines three different genetic cross scenarios with varying outcomes. The first scenario involves a male with hemophilia and a non-carrier female, resulting in 50% of offspring being carriers or non-affected. The second scenario includes a male with hemophilia and a carrier female, leading to a 25% chance for each possible genotype and phenotype among the offspring. The third scenario features a normal male and a carrier female, resulting in a 25% chance for each genotype and phenotype. The paragraph stresses the importance of accurately recording and grouping genotypes and phenotypes when calculating sex-linked inheritance.

15:02

📊 Understanding and Explaining Sex-Linked Inheritance

The fourth paragraph discusses how to explain sex-linked inheritance, particularly focusing on the differences in susceptibility between males and females. It highlights that males are more affected due to having only one X chromosome, which lacks a second X to mask the presence of a recessive disorder allele. The paragraph also addresses how to answer questions about the percentage of children with a disorder, emphasizing the need to distinguish between males and females when calculating these percentages. It provides a structured approach to explaining sex-linked inheritance, including stating parents' genotypes, explaining allele inheritance from each parent, and discussing why males are more likely to express the disorder.

20:05

👋 Conclusion and Terminology Recap

The final paragraph concludes the video script with a recap of key terminology related to sex-linked inheritance. It differentiates between autosomes, which are not sex chromosomes and are associated with autosomal diseases, and gonosomes, which are the sex chromosomes (X and Y) and are relevant to sex-linked disorders. The paragraph also distinguishes between recessive and dominant traits in the context of sex-linked disorders and clarifies the difference between phenotype (observable characteristics) and genotype (alleles on sex chromosomes). It corrects a misconception about using 'carrier' as a phenotype and ends with a reminder of the importance of understanding these concepts for grasping sex-linked inheritance.

Keywords

💡Sex-linked disorders

Sex-linked disorders are genetic conditions that are linked to an individual's sex chromosomes. These disorders are predominantly associated with the X chromosome, as males have only one X chromosome and are thus more susceptible to inheriting these conditions. In the video, red-green color blindness and hemophilia are mentioned as examples of sex-linked disorders. The script explains how these disorders are inherited and how they manifest differently in males and females due to the presence of two X chromosomes in females, which can mask the effects of a recessive gene.

💡Gonosomes

Gonosomes, also known as sex chromosomes, are the chromosomes that determine an individual's biological sex. In humans, these are the 23rd pair of chromosomes, which include the X and Y chromosomes. The video script explains that females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY). Understanding gonosomes is crucial for comprehending how sex-linked disorders are inherited, as these disorders are directly related to the genes present on these chromosomes.

💡Autosomes

Autosomes are the first 22 pairs of chromosomes in humans, which are not involved in determining sex. They are responsible for various other traits and characteristics. The video script contrasts autosomes with gonosomes to emphasize that sex-linked disorders are specifically related to the sex chromosomes, while other genetic conditions can be linked to any of the autosomes.

💡Punnett square

A Punnett square is a diagram used to predict the genotypes of offspring in a genetic cross. It is named after Reginald C. Punnett, who introduced it in 1905. In the video, Punnett squares are used to demonstrate how sex-linked disorders are inherited. The script walks through examples of how to calculate the likelihood of offspring inheriting conditions like red-green color blindness and hemophilia by using Punnett squares to visualize the genetic combinations.

💡Recessive disorder

A recessive disorder is a genetic condition that is expressed only when an individual inherits two copies of the recessive gene, one from each parent. In the context of the video, red-green color blindness is described as a recessive disorder linked to the X chromosome. The script explains that males are more likely to exhibit the disorder because they have only one X chromosome, and if it carries the recessive gene, they will express the condition.

💡Carrier

A carrier is an individual who possesses a gene for a recessive disorder but does not exhibit symptoms of the disorder. In the video, the script discusses how females can be carriers of sex-linked disorders, such as hemophilia, because they have two X chromosomes. If only one X chromosome carries the recessive gene, the other normal X chromosome can mask the disorder. The video uses the term 'carrier' to describe a mother who can pass on the recessive gene to her offspring.

💡Phenotype

Phenotype refers to the observable physical or biochemical characteristics of an individual, which result from the interaction of its genotype with the environment. The video script explains that in the context of sex-linked disorders, phenotypes can vary between males and females. For example, females may be carriers of a disorder without exhibiting symptoms (phenotype of being a carrier is not used), while males with the same genetic condition may show clear symptoms due to having only one X chromosome.

💡Genotype

Genotype is the genetic composition of an individual, describing the specific set of genes inherited from the parents. In the video, genotypes are discussed in relation to sex-linked disorders, with examples of how different combinations of alleles on the X and Y chromosomes can result in different outcomes for males and females. The script uses genotypes to explain how traits are passed down and how the presence of a dominant or recessive allele on the sex chromosomes influences the expression of disorders.

💡Red-green color blindness

Red-green color blindness is a common sex-linked disorder discussed in the video. It is a condition where an individual has difficulty distinguishing between certain colors, particularly reds, oranges, and greens. The script uses this condition to illustrate how recessive genes on the X chromosome can affect males more frequently than females, as males have only one X chromosome and thus are more likely to express the trait if they inherit the gene.

💡Hemophilia

Hemophilia is a bleeding disorder mentioned in the video script as another example of a sex-linked disorder. It is caused by a deficiency of certain clotting factors in the blood and is typically inherited in an X-linked recessive pattern. The video explains how hemophilia is more common in males because they have only one X chromosome, and if it carries the gene for hemophilia, they will exhibit symptoms. Females, on the other hand, would have to inherit the gene on both of their X chromosomes to express the disorder, which is less likely.

Highlights

Introduction to sex-linked disorders and how they are inherited.

Explanation of the structure of chromosomes, specifically the sex chromosomes (X and Y).

Differentiation between autosomes and sex chromosomes in determining biological sex.

Description of the genetic makeup of males and females in terms of sex chromosomes.

Importance of understanding chromosome combinations for learning about sex-linked disorders.

Discussion on why females are less susceptible to certain disorders due to having two X chromosomes.

Explanation of how males, with one X and one Y chromosome, are more susceptible to X-linked disorders.

Introduction to X-linked disorders and their representation on the X chromosome.

Example of a sex-linked disease: red-green color blindness, its symptoms, and how it is inherited.

Demonstration of a red-green color blindness test and interpretation of results.

Genetic representation of sex-linked diseases using superscript letters on the X chromosome.

Illustration of genetic cross using a Punnett square to predict inheritance outcomes.

Explanation of the inheritance pattern in an example with an unaffected father and a carrier mother.

Discussion on how to determine the genotype and phenotype of offspring from a genetic cross.

Clarification on the difference between genotype and phenotype in the context of sex-linked disorders.

Introduction to hemophilia as another common sex-linked disorder and its inheritance pattern.

Tutorial on calculating sex-linked inheritance using hemophilia as an example.

Emphasis on the importance of accurately writing genotypes and phenotypes in genetic crosses.

Explanation of how to group and calculate the percentages of different genotypes and phenotypes in a Punnett square.

Differentiation between writing about carriers in questions versus describing phenotypes.

Guidance on answering questions that ask for the percentage of children with a sex-linked disorder.

Instructions on explaining sex-linked inheritance, including stating parents' genotypes and inheritance patterns.

Terminology recap including autosomes, gonosomes, recessive and dominant traits, phenotype, and genotype.

Transcripts

hi everybody and welcome back today

we're going to be looking at sex

linked disorders and we're going to go

through exactly how you inherit these

diseases

how to calculate them in a punnett

square and also we are going to look out

how do you explain these in longer

questions when you have to explain it

perhaps in a paragraph

so a fundamental aspect of this topic is

understanding

the structure of the chromosomes now in

the photograph in front of you

you have what we call our gonozomes

or the sex chromosomes

now when we speak about gronosomes we

are talking about the

x chromosome and the y

chromosome essentially these are the

23rd pair in humans that dictate our

biological sex

autosomes are the 22 other

chromosomes that humans have and they

are not linked to our sex determination

now in this photograph

the very large chromosome is represented

by

our x so that is the x chromosome the

smaller chromosome in blue

is the y chromosome now

depending on whether you are male or

female females will have

two x chromosomes and

males will have an x and

a y it's important to know these

combinations of by heart because it's

going to help you learn about these sex

link disorders a lot

more easily now you will notice that

especially and fundamentally females

have two

x chromosomes which makes them a lot

less susceptible to disorders because

if one of their x chromosomes is damaged

the other one can help

it out it can fix the problem in males

on the other hand you will notice that

they only have

one x chromosome and because an x and a

y

are actually not homologs in other words

they're not an actual homologous pair

they're not perfectly identical to match

um whatever is on the y actually can't

help if there's something broken

on the x now in this video i'm only

going to talk about

x linked disorders which means that

these are sex

links disorders but they're only found

on the x chromosome you do also get ones

on the y

so a very common example of a sex link

disease

is red green color blindness

now essentially red green color

blindness means that you have the

inability to see certain shades of color

and alongside here i have included a

very simple red green color blind test

if you cannot see the number in the

circle there's a possibility

that perhaps you do have color blindness

you might see the incorrect number or a

partial number

if you're hoping to know what the

correct number is it's a 2

that's hidden inside of there often

people with red green color blindness

confuse the reds the oranges and the

yellows and greens with each other

now this particular kind of sex-linked

disease

is carried on the x chromosome and it is

a recessive

disorder that means that we are going to

use a small letter to represent it but

this time we're actually going to write

it

as a superscript at the top of the x

if you don't have the disorder then your

x chromosome is going to carry a

capital r on it and that means you don't

have it

in other words in order for us to see

the variations of how this turns out

let's have a look at this example

along on the left so what we have here

is an

unaffected father and we have a

carrier mother now let's talk about the

unaffected father

if the unaffected father doesn't have

the disorder that then means that his x

chromosome

will have a capital r on it and he will

have

a y and there's nothing on the y because

this is not a y

linked disease it is an x chromosome

disease

the mother on the other hand is what we

call a carrier

what that means is that one of her

chromosomes carries it and the other

doesn't

so if we were to do her genotype she

would have one capital r

on her x chromosome and one small case

r or lowercase r that means she's

carrying that disorder

now what they've done lower is that

they've done a genetic cross like a

punnett square but with pictures this

time

and what we have is four possible

outcomes of the offspring first of all

we have an unaffected son and an

unaffected daughter now the only way

that that's possible for the unaffected

son

is that his x chromosome which he gets

from his mother

because you can only get wise from

fathers the x chromosome he got from his

mother

can only be the

capital r he can't inherit the small r

if he did

he would have the disorder and so that

then means

that the only possible thing that is on

his x chromosome

is going to be a capital r

and a y our daughter who's unaffected on

the other hand

she has two x chromosomes and now we

need to know

well what are her r's does she have two

big r's little one

what does she have well if we look at

the fact that she is not a carrier

it means that she is going to inherit

one allele from each parent and she's

going to inherit one capital letter from

her father

and she's going to inherit the other

capital letter

from her mother making her therefore

have a genotype of

a capital r on the one x and a capital r

on the other

then we look at the carrier daughter the

carrier daughter just like her mother

will have the same phenotype

she will have an x with a capital r on

it

where did she get that capital r from

she received

that one from her father because that's

all he can give to his daughters he

can't give a y

chromosome the other r on the other x

however

was inherited by and from the mother

because that's the only other place she

could have got this small r which she

carries

and so that's where her small r comes

from finally we have the affected sun

the affected sun is going to be x y

and what do we find on his x chromosome

well he inherited his y chromosome from

his father so there's nothing that we

can receive

from the dad that will tell us if

they're colorblind what's important is

where did he get that affected allele

from

and he received it from his mother so

that means the

sun will have a small letter r on his

x so to round this section off

just to ensure that we know exactly how

this works

if you are two x's

you're female you must have two small

r's on both of your x's to have the

disorder

if you are a boy you only need

one small letter r on your x

and that's because you only have one

x allele to work with on the other hand

in our dominant or capital r you can

have a girl

who has two capital rs

you can have a boy with a capital r

which means he doesn't have the disorder

and the final option oh i've made a

mistake let's just quickly rub that out

the final option is if you have

a female who is a carrier

and the female i'm just going to put it

below here because i'm running out of

space

is going to be a capital r and a

small or lower case r

now we need to look at how do you

actually calculate the sex linked

inheritance and for this one i'm going

to use hemophilia which is another very

common kind of sex-linked disorder that

we do in school

and these are three different examples

with three slightly different

outcomes it's been a little bit

challenging also to write these

h's as superscript i know that they're

written here lower

remember when we write them we want to

write the x and then we want to put it

at the top

like that uh just for reference when

you're writing this

in school so let's have a look at the

first example so our first

example is a male with hemophilia

now you are going to set out your

genetic cross like you normally do

you're going to have your geno and

phenotype of the parents

meiosis gametes fertilization and then

you're going to draw your punnett square

like you normally would you you

basically draw your normal

genetic diagram except the lettering

is just slightly altered and with this

one the question would have said a male

with hemophilia so here is our male with

hemophilia there is his one allele and

there is his other sex chromosome

and then we have a female who is a

non-carrier

sometimes they call them non-carriers

sometimes they can call a female without

hemophilia

sometimes they will also say it's just a

normal

female essentially what that means is

that this female has

two capital h's in other words she is

not a carrier of the disease and

she does not have it either

now you would do your genetic cross like

you normally would and these would be

our

outcomes now the way in which you write

your answer is

really important and so that's what i'm

going to show you now in terms of

calculating it

now what we need to do is we need to

group together our genome and phenotypes

and so looking at our punnett square we

can first of all group together our

genotypes

we're going to look at the females first

and these two females carry the same

genotypes we group them together so

that's 50 percent and then these two

male genotypes are also the same and so

we group those together also

50 the phenotype is

a reflection of that where there are 50

females without hemophilia it's

important to write that they are without

hemophilia

and that they are females this is a

sex-linked cross so you must give

the sex of the individual and then 50

males without

hemophilia now let's have a look at the

second example the second example will

have something

in the question along the lines of a

male with hemophilia

and so here are his alleles

and they are always placed together

let's not forget that

and then the next important component is

that this cross now has a female

carrier it's important to remember that

the word carrier is actually not a

descriptive word that you're allowed to

use when you talk about

the phenotype at the very end and i'll

show you exactly what i mean by that

they can use it in the question to

describe the female

but you can't use it to describe them

later on when you write out the

phenotype but i'll show you what i mean

and here is our female carrier we know

she's a carrier because she has one

capital

h on her x and one lower case h on the

other

now we are going to multiply this into

the table and let's write out our pheno

and genotype

all right now this genome phenotype is a

little bit longer because we've produced

essentially four very different

individuals and so let's have a look at

the genotype

so we're going to group all the same

genotypes together now in this

particular punnett square all the

genotypes are different this female

represents 25

this female here represents 25 this male

is 25 and this male is also 25

the phenotypes follow a very similar

distribution 25 percent of females

without hemophilia

we then have 25 females with

hemophilia it's important to note that

these 25 percent of the females with

hemophilia

won't actually be born but because a

punnett square is working out

probability

you still need to provide the

probability of a child

inheriting the disorder don't get caught

out on questions

that are asking about hemophiliac

females just because you know that

they're not actually born

but they will essentially be formed

and often a mother goes through a

miscarriage we then have 25

males without hemophilia and then 25

males with

hemophilia now let's get to the third

example

in this final one we look at a normal

male which as we can see here he has his

dominant

h on the x and the y chromosome

and then we have very importantly now a

female

carrier you will now notice that

whenever

i'm going to write about female carriers

we don't actually call them that when we

write our phenotypes but you'll see now

as i do the calculations and i write out

our genome and phenotypes you multiply

into the punnett square

and you write down your pheno and

genotype results

now this final genome and phenotype

reveals a very important way in which we

need to group our results

the genotype is very simple all we need

to do

is group them so we have 25 percent

two x's with capital dominant h's we

have an individual

a female individual who has a capital h

of a small h

25 have a capital h a dominant allele

and 25 percent of the males have a

a recessive h on their x and that's how

we record it

what i want to bring your attention to

is how you write the phenotype

50 of the females are without

hemophilia you do not write 25 percent

without

and then 25 female carrier technically

being a carrier is not a phenotype

you can't actually write that down

because it's not a physical

characteristic that can be observed

it is only a genotype i know in

questions that they will refer to them

as carriers and they have to because

that's how they're indicating that

they're heterozygous that they have a

big letter and a small letter or a

dominant and a recessive allele present

but you cannot write them that way we

then still write however the males the

same

and that we have 25 percent males

without hemophilia

and 25 males with hemophilia the last

thing that is really critical that goes

with any sex linked inheritance is

questions like the following

let's say for example three they ask you

to tell them

of the children what percentage

has hemophilia now of the four children

in example number three how many

have hemophilia now of all the children

that's boys and girls

and of all three only 25

now that refers to all the children

but what happens if the question was

what percentage of the males

have hemophilia now if we

only look at the boys we only look at

the males

and there is only one of the two males

that have it that then means that of the

boy

children 50 percent of the boy

children have hemophilia it's really

important

to read the question carefully and to

see are they asking about the children

as a whole

or are they asking about the boys or the

girls only

next we need to look at how are you

going to explain this type of

inheritance

often they will ask you how do you

explain the sex-linked inheritance

you've just seen now in the hemophilia

or

perhaps in the red green color blindness

and what you need to do

in it's a very basic structure is you're

always going to

state the mother's genotype and that

means that you need to give

what her letterings are

on her x's and her y's on her x's excuse

me

the same goes for then stating the

father's

genotype so you're going to state their

genotypes

for example let's say that our

mother's genotype is a x

with a capital h and a x

with a lower case you need to state that

and then for the father

you need to do the same let's say for

example he has a

dominant allele on his x chromosome

then what you need to do is you need to

explain how

this occurs through the following things

you are going to then explain how you

inherit one

allele from each parent that's important

males inherit only a y chromosome from

their father

and an x chromosome from their mother

females on the other hand inherit an x

chromosome from their mother

and their father now depending how long

the question is and what exactly it's

asking

they may also ask why are boys more

affected by sex-linked disorders than

girls

this is where you will then include a

section in your

answer about the fact that males only

have one x chromosome

and because they only have one x

chromosome they are more

likely to inherit the disease

why are they more likely to inherit the

disease because they do not have another

x chromosome to mask it in other words

if we look back up at this father's

genotype you'll see he only has one x

chromosome with the capital h on it the

dominant allele

if he had a recessive allele there's no

other allele that can protect him from

that disorder

the y chromosome is too small it doesn't

have enough information on it

and it can't mask anything on the x

however on this mother's genotype you'll

notice she has a dominant allele and she

has a recessive allele

which technically means she's carrying

hemophilia

but because she has two copies of the

alleles

one dominant and one recessive her

dominant allele

masks the recessive allele therefore she

does not suffer from the disorder

last but not least let's do a quick

terminology recap

we spoke about autosomes and gonozomes

autosomes are the first 22 chromosomes

and this is where you find autosomal

diseases if you've come across an

autosomal disease

you are not going to use x's and y's

you still use the standard a

and small letter a or you can even use

any other lettering depending on what

they want you to use but essentially

you only need to use your letters of the

disease you do not need

to use any other x's and y's

gronosomes on the other hand are the sex

chromosomes the x and the y and that's

what we dealt with today

you get recessive and dominant traits

and this will then depend on whether or

not the sex link disorder is a dominant

or a recessive sex-linked disorder

remember that for it to be recessive

in females you're going to need two on

each of her chromosomes so one on each

in males however they only need one

recessive allele because remember they

only have one

x in hemophilia we looked at a bleeding

disorder

that is found in males and carried by

females no female hemophiliacs

are born or exist red green color

blindness

is a type of sex lick disorder which

both males and females experience

although males are more commonly found

to have red green color blindness

and then we spoke about the phenotype

which is the physical characteristics of

the individual and what they look like

remember we can't have a carrier as a

phenotype

and lastly the genotype essentially the

alleles that we find

on their sex chromosomes thank you

everybody i hope this video

has helped you and i will see you again

soon bye