Need help with biology homework; will give up my won

[WestWorld]

.1.    Tay-Sachs disease is inherited as an autosomal recessive. It is a devastating neurological disease that results from the lack of a normal enzyme, hexosaminidase A, whose job is to metabolize lipids (gangliosides) that are found in brain cells. A young couple is told that they are carriers for this disease. Explain, as you would to this couple, their likelihood of having a child with Tay-Sachs disease. Show the Punnett square that illustrates their chances. 

 

2.Based on your understanding of sex linkage, describe in detail why most hemophiliacs are male. Can females have hemophilia? Describe how they could inherit this disorder. Can males be carriers for hemophilia? Explain.

 

Though 2 would be nice as well, I mostly need help with question 1

[Mystic]

I think you just make a punnett square where each parent has one dominant allele and one recessive allele, and then calculate the % that has the disease (25%).

 

Edit - Like this:

 

[Ddeona Oneul Bame]

Did you already do the Punnet square?

[tearose]

Lemme try to type out a punnett square

 

    T      t

T  TT   Tt

--------------   

t    Tt    tt

 

Let T represent the normal trait, and t represent the recessive tay-sachs trait. Since it's recessive, you need two t's rather than just one. So there's a 1/4 chance that their child will have the disorder, assuming they both are carriers (have just one tay gene)

[Moa_Nunu]

1.) Parents both carriers Tt x Tt so their chance of having a child with tt is 1/4 or 25%.

 

2.) Females can have hemophilia but it would be hard. Most hemophiliacs are male because they only need 1 X allele to be affected. Males can't be carriers. They either have hemophilia or they don't.

[tobe]

1. 25% chance of their child having the disease. If you want a punnet square its Aa vs Aa

 

2. you can basically look that up online

[tearose]

Males have hemophilia more often because the disorder is linked thru the X chromosome only. Girls have two of those, guys have one of those. So it statistically more likely for the guy to have all x chromosomes (one) with the trait. Girls need double the chance.

[Moa_Nunu]

It's so weird. Why do I love doing other people's homework but I hate doing mine? lmao

[Ringo]

For things like hemophilia and certain types of color blindness, the trait is linked to the X chromosome. Because females have two copies of the X chromosome (excluding Turner Syndrome women, which is a whole other thing), the chance of them inheriting a disorder relating to the biological sex is less. It's not foolproof or anything, as there are symptomatic carriers as well.

 

Anything linked to recessive genes needs two copies of that gene. In the example you gave, there would be a 25% chance of the child inheriting the disorder, 50% chance of the child being a carrier, and 25% chance they will neither have the disorder nor be a carrier when using punnet squares.

[Shiraz]

So many smart people, I feel so dumber

[indigo]

Females can express hemophilia A/B as the result of both copies of the X chromosome being affected, or X-inactivation of the functional copy. The first is the heritable factor, the latter is epigenetic. 

 

But generally females cases are more mild, because inheritance of two defective X is rare and normally some of her cell carry the functional copy. 

 

And males are carriers of A/B, but they only pass it to their female offspring. 

 

It can also be a mutation, as in neither parent is carrier and it is the result of a random mutation. 

[WestWorld]

OMG YOU GUYS ARE ALL ANGEL ILL BE JANDING OUT MY WONS TOMORROW