How much do you know about genetics?

[theWayden]

These are some questions from my human genetics class, i thought it would be interesting to share and see what answers you come up with.

case1:
Female has an unidentified genetic disease
Grandfather has disease
Mother of the female does not
Females older sister has disease, two younger siblings do not

dominant, recessive, sex linked, other?

case2:
Female Displays a trait
Husband and Females brother do not display the trait
Female has 5 children 4 of which are affected
Both parents of the female display trait

dominant, recessive, sex linked, other?

case3:
Male Displays a trait
Wife and parents do not display trait
Male has a brother and sister who also do not display trait
Brother has 2 daughters who do not display trait
Sister has 2 sons who display trait
The male has 3 children who do not display the trait
The males oldest daughter has a son who displays trait

dominant, recessive, sex linked, other?

Now i had to make a pedigree analysis for each of them but i dont want to put you guys through that =) just state whether you think it is one of the choices and why. i only haven't been able to figure out number 2

 

[Bellalee]

1 might be recessive but I'm doubting myself. So dont quote me on that.

 

[artgecko]

1. recessive
2. dominant
3. sex-linked

 

[herpencounter]

1. recessive
2. dominant
3. sex-linked

:main_yes::main_yes::main_yes:

 

[eyelids]

I'm reminded of problem solving in my elementary school's math class... Year uhhh... Fourth grade maybe...

What is sex-linked? Give me a leo equivalent please...

 

[erik]

case2:
Female Displays a trait
Husband and Females brother do not display the trait
Female has 5 children 4 of which are affected
Both parents of the female display trait

dominant, recessive, sex linked, other?

I like the second! I would say it's dominant (R):

Parents: Rr x Rr
Female: Rr
Husband: rr
Brother: rr
5 children: Rr, Rr, Rr, Rr, rr

Would that make sense? (R for random )

Eyelids: sex-linked means that only one gender is sensitive to getting the trait/disease, like color blindness only affects males.

 

[herpencounter]

I'm reminded of problem solving in my elementary school's math class... Year uhhh... Fourth grade maybe...

What is sex-linked? Give me a leo equivalent please...

Geckos don't have an XY chromosome, so... I cant give an example lol.

Female have XX chromosome (two full chromosomes) and males have an XY chromosome (one full chromosome and 1 1/2 a chromosome). Any gene located on the female XX or male XY is called a sex linked.

Example of a sex linked disorder...

Colorblindness: A resecive trait.
For females... Because they have two full chromosomes, they need both colorblindness genes to express it. Males only have 1/2 a chromosome, they can only carry 1/2 the gene, it gets expressed in the heterozygous form.
An example.
http://www.humanillnesses.com/original/images/hdc_0001_0002_0_img0128.jpg

Pic. of XX and XY.

http://anthro.palomar.edu/biobasis/images/homologous_and_hemizygous.gif

http://staff.um.edu.mt/acus1/Mendel1-web_files/image004.jpg

 

[herpencounter]

I like the second! I would say it's dominant (R):

Eyelids: sex-linked means that only one gender is sensitive to getting the trait/disease, like color blindness only affects males.

Wrong! It is mostly expressed in males. Because, females need both half's of the gene. While males need one.

Females have a full chromosome and males have 1/2 a chromosome.

Pic. of XX and XY.

http://anthro.palomar.edu/biobasis/images/homologous_and_hemizygous.gif

http://staff.um.edu.mt/acus1/Mendel1-web_files/image004.jpg

 

[Bellalee]

:main_thumbsup: herpencounter


You should be a genetics teacher.. much better then mine was.

 

[herpencounter]

:main_thumbsup: herpencounter


You should be a genetics teacher.. much better then mine was.

HAHA. Thanks for the complement.

Yeah... I think I might go to school for molecular genetics. Get a master's or doctorate. :main_rolleyes: Get butterfly's just thinking about it LOL......

I don't know a millionth of whats out there and I want to know it all... GAH!!!




J.

 

[theWayden]

:main_thumbsup: herpencounter


You should be a genetics teacher.. much better then mine was.

ditto =) so we all agree the 2nd one is dominant? if it is dominant then how did both the parents have the trait an only pass it to one child and not the other? should 100% of the offspring have the trait? And for the 3rd one i figured it might be recessive sex-linked?(if thats even possible) since the original male did not have the trait but one of his sons did? this stuff gets very confusing =)

 

[herpencounter]

ditto =) so we all agree the 2nd one is dominant? if it is dominant then how did both the parents have the trait an only pass it to one child and not the other? should 100% of the offspring have the trait? And for the 3rd one i figured it might be recessive sex-linked?(if thats even possible) since the original male did not have the trait but one of his sons did? this stuff gets very confusing =)

Thanks! And......................

The mother and father have this gene. So if this gene is recessive then ALL there children will display this trait. So its not recessive.

If it was sexed linked then the brother would have it no choice (regardless if it is dominant or recessive)!

If you breed an animal that express a gene to another animal that expresses the same gene. If you get babies that express it and babies that don't it is dominant.

I could get deeper into it but it is not needed for the question LOL.

J.

 

[Bellalee]

Molecular genetics.. awesome! Soooo... tutor me next semester when I am voluntarily (and stupidly might I add) that class...
j/k....

 

[herpencounter]

Molecular genetics.. awesome! Soooo... tutor me next semester when I am voluntarily (and stupidly might I add) that class...
j/k....

LOL.


I love this thread! I can answer something that is not about geckos. hehe...

 

[theWayden]

glad i made it then =) an thanks for all the help ill be sure to post more of my genetics hw next time

 

[oceanoasis]

just a guess
case 1: the females mother and father have a recessive form of the disease Rr X Rr
case 2: F- rr M-Rr both parents rr, or maybe a codominant gene? thats a good one.
case 3: sex-linked recessive.
just guessing, but at the moment it works in my head.