Q@Q Drill time ❷ - cardio69

[ArchivalUser]

Jack and Betty have had two children with Down syndrome. Jack’s brother has Down syndrome and his sister has two children with Down syndrome. On the basis of these observations which of the following statements is most likely correct?

a) Jack has 47 chromosomes
b) Betty has 47 chromosomes
c) Jack’s and Betty's children each have 47 chromosomes
d) Jack has 46 chromosomes
e) Jack’s sister has 45 chromosomes
f) Betty has 45 chromosomes
g) Jack’s brother has 45 chromosomes


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[ArchivalUser]

Time's UP.

[ArchivalUser]

I think the extra copy of 21 chromosomes is gotten by chance, i think factors like age of mother might have an effect.
Most parents that have kids with Downs syndrome are genetically normal
I think C

[ArchivalUser]

Honestly i don't think there is enough info in q to answer... no offense cardio,

Down reasons - non-disjunction, uneven translocation and mosaicism

If i were to guess i say Jack and Betty are genotypically normal so 46 D....

[ArchivalUser]

TRANSLOCATION: Robertsonian translocations/RT.

Happen btw acrocentric chrom 13, 14, 15, 21 and 22 in which as you know the short arms/satellites are lost & long arms are fused btw the two chrom. And as u know short arms not gone because problem as genes lost are 1ry those rRNA (present multi-copy through the gene library)

Now, my Qs for both of you would be -> individual who carries RT have what # of chromosomes? And are they phenotypically norm?

Their children & Jack’s brother who preach in Q have -> Down syndrome, have 46 chrom, but one of this chrom is the translocation that has an extra copy of long arm/chrom 21. From what been given, there is no reason we think Jack’s honey/betty has any chrom aborm. Such cases are frequently but not always-> Familial/& translocated chrom is inherited from 1 of the parents (usually the mom), who is a carrier of a RT.
The only “statement most likely correct” is that Jack & his sis ( who are unaffected) and phenotyp norm carries would have “TRANSLOCATION” & have 45 chrom. "E" correct ans for what been ask

@Peshka its lovely Q ( make sure see what been ask of you) Please read my Qs with care hard that’s reason not much ppl to ans on time))

Fin.

[ArchivalUser]

I see so RT carrier is genotypically abnormal 45 chr, but phenotypically normal.

it is a cool q. thanks

[ArchivalUser]

(:
Well DONE.