pop. genetics help on couple questions please!

nf_7138

wrote...

14 years ago

pop. genetics help on couple questions please!

Need help on the following questions:

1) How could you tell if Drosophila melanogaster is DpDp or Dp+?

2) How would you set up the problem to find the probability that 3 out of 5 children will have congenital analgesia(pp) with Pp x Pp parents?

3) Describe the Punnett Square of the Drosophila melanogaster cross with cream eyed males (c^a c^a X^w-e Y) with wild type females (CCX^w+ X^w+).

4) Explain the statement--Having 2 active X chromosomes is a lethal condition for a human female embryo. What happens to prevent this (include details)?

thanks so much for your help guys!
i dont have a book or any kind of material to help me with this thats why i need help

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bio_man

wrote...

Educator

14 years ago

Hmm... For number 4, if one of the X chromosomes is damaged, say it has a gene that produces an insignificant amount of proteins due to some sort of mutation, the other X chromosome could make up for the lose of the homologous chromosome by producing the proteins the body needs. This can only be related to females because only females have two X chromosomes, whereas males only have 1 X and 1 Y.

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Nicole Author

wrote...

14 years ago

If anyone can please answer the remaining questions ASAP..I'd greatly appreciate it!!

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duddy

wrote...

Staff Member

14 years ago

DpDp or Dp+

How could you tell, cross it with a homozygous dominant fly. If it's Dp+, the offspring will all show dominant traits.

Dp +
+ Dp+ ++
+ Dp+ ++

Remember:

Fruit fly researchers use a different type of symbolism to represent their genetic crosses. They use a plus sign (+) to indicate anything that is the “wild” type and a letter (or sometimes two) to represent a mutant allele (capital if the mutation is a dominant allele, lower case if it’s recessive). Thus a fruit fly with a homozygous grayish-yellow body would be labeled as “++” for body color while a black-bodied fly would be “bb” and a heterozygous fly would be “+b”. The genotype for normal wings would also be symbolized as “++,” while the allele for vestigial wings is “vg” so a fly that is homozygous recessive for that gene would be “vgvg” and a heterozygote would be notated as “+vg”. Similarly, normal red eyes would be “++,” cinnabar eyes would be ”cncn,” and a heterozygote would be “+cn.”

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