Pedigree Analysis 1: How to solve a genetic pedigree No. 1

Biology teacher Andrew Douch explains how to systematically study a genetic pedigree, to determine the most likely mode of inheritance.

Category:

Education

Tags:

• Andrew Douch
• Douch
• Douchy
• Biology
• genetics
• pedigree
• inheritance
• mendelian
• trait
• phenotype
• genotype
• family

[Soccercardman7]

so if dad has XAY and the mom is XaXa then how would this work?

[andrewdouch]

@Soccercardman7 Then all their daughters would be XAXa and all their sons would be XaY

[ASSHOLELA]

because John fathered 2 children with the w/W genotype, Mary suspects that he is the one who gave the w gene to their child.

How do you calculate the probability than John, as opposed to Mary, gave the child the w gene?

The tricky part is all their genotypes John, Susan and Mary are unknown,can be W/ W or w/W , definately not w/w because they are not white haired! but it is supposed that genetic counsellors can work out the probability empiracally. How do you do this?

[andrewdouch]

@ASSHOLELA - I'm not sure ... It's tricky, because it's possible that John is Ww and both women are WW, but it's also possible that both women are Ww and John is WW. It's even possible that all three are Ww! Each of them (before having kids) had the same chance of being Ww. So all we can deduce now (I think) is that the chance of Mary being a carrier, is equal to the chance that Susan is a carrier, and John's chance of being a carrier is double (since he has had two babies with a w allele).

[andrewdouch]

you are welcome :)

[girlclasse]

I appreciate your work here, but I have to admit that I'm quite confused with pedigrees after watching this.

[andrewdouch]

@girlclasse - Pedigree analysis is complex - there's no doubt about that... and I think most people find it challenging. So don't feel too bad about that. There are a few more examples on here, you may find that if you watch each several times, it will start to seem less confusing.

[pur33z]

I've used this for the past 2 years.. thanks bro helped a lot.

[Heychick13]

THANK YOU!! that helped me understand pedigree charts. i searched for videos cause i'm scared of my science teacher.

[baidooish]

u are awesome i was studying for my MCAT and seeing ur video made my day

[Gerbilinator]

YouTube-My biology class

[TheBabgi]

you made my life a hell of a lot easier now, greatly appreciate it!

[simin19100]

Thanks so much.