Question

The pedigree below traces the inheritance of alkaptonuria, a biochemical disorder. Affected individuals, indicated here by the filled-in circles and squares, are unable to break down a substance called alkapton, which colors the urine and stains body tissues.

(Will share the pedigree image)

a. Does alkaptonuria appear to be caused by a dominant or recessive allele? Explain.

b. What is George’s phenotype?


c. Is it possible for Daniel to have a child with alkaptonuria? Explain.



d.How would knowing the pattern of inheritance influence the treatment plan for this disease?

Answer 1

Do you know the rules for assigning types of disorders, i.e autosomal, sex-linked, mitochondrial?

Answer 2

I just learned about X-link because of a "color blindness" question. However, I have no idea what autosomal and mitochondrial are.

Answer 3

For the first part of the question, part "a", would the answer be recessive? Because the mother has the dominant gene, and the father isnt effected... Yet, only half of their kids are effected?

Answer 4

Which mother?

Answer 5

Arlene?

Answer 6

Alright well yes.

Answer 7

That's correct.

Answer 8

Open study stopped working for some reason. Sorry about that.

Answer 9

No worries :)

Answer 10

I am extremely confused about genotype, and phenotype. Phenotype is how something looks on the outside, right? How would i display that in letters like "bb, Bb" etc?

Answer 11

For part b, i need to figure out george's phenotype.

Answer 12

Genotype: is in letters- represents both alleles. eg. Bb for Broen and blue.
Phenotype: takes on the appearance of the dominant alllele eg. brown eyes.

Answer 13

Phenotype isn't in letters its words.

Answer 14

How is phenotype written for disease?

Answer 15

You would write whether they may have the characteristics of the disease or not eg. normal red blood cells, crescent red blood shaped cell for sickle cell aneamia.

Answer 16

Okay, awesome. The only traits they gave me in the question were "...which colors the urine and stains the body tissue." Could I simply write that he has normal colored urine and body tissue?

Answer 17

Or is my professor looking for more?

Answer 18

Exactly- it's their characteristics. You might add has the disease name, like she suffers, he doesn't suffer if you like.

Answer 19

Yay! Thankyou so much. Only two more bullet points for me to cover now. I've been staring blankly at the pedigree, trying to figure out if daniel could have a child with alkaptonuria.... My first guess would be possibly, or no. He doesnt have the disease himself, so i would need to figure out if he carries the recessive trait, right? (Actually... hold on). That would also mean that his partner would need the recessive trait as well, right? Or?

Answer 20

(Sorry if i get extremely confusing!)

Answer 21

Yes yes your on the right track...

Answer 22

I think I'm going to say that it would be impossible, unless his mate had the recessive trait as well. Because you need two recessive genes, correct?

Answer 23

Hmm it's still possible right?

Answer 24

I should probably make a punnett square... shouldnt it?

Answer 25

i*

Answer 26

Think about it you would have to draw up many- the partner could be homozygoues recessive for the disoder or heterozygous.

Answer 27

homozygous*

Answer 28

I thought that if you had the recessive gene, you wereonly a carrier?

Answer 29

Would Daniel still have a partner homozygous or heteroygous for the disease when he's a carrier?

Answer 30

homo = the same, and hetero = different.. right?

Answer 31

Heterozygous would mean you have a dominant allele and recessive.

Answer 32

You carry the recessive allele but you do not have the disease at all.

Answer 33

But it's still possible, because we have no idea who his partner is. It depends on who his partner is, right?

Answer 34

Yes. Though i think it's unlikely.

Answer 35

Possible, but unlikely.

Answer 36

How can I be sure that he carries the recessive gene, though?

Answer 37

I don't think it matters much. I think I get what you are saying now.

Answer 38

If he had the dominant trait, he would have it. If it's recessive, he'd be a carrier but not have the trait himself. If his partner had the recessive trait (which isnt likely), its possible for them to have a kid with the disease.

Answer 39

His father has two recessive genes- sufferes from alkaptonuria. His wife is normal.

Answer 40

So lets say his fathers genotype is rr and wife RR. He has to be a carrier 100%.