Understanding Genetics Through Fruit Fly Inheritance

If a homozygous dominant male fruit fly is crossed with a female fruit fly with vestigial wings, what percentage of their female progeny will have wild-type wings?

• A. 50%
• B. 25%
• C. 100%
• D. 75%

Answer: (C)

To understand why the answer is 100%, let's first clarify the genetic traits involved in this question. The male fruit fly is homozygous dominant for the wild-type wings, which means it carries two dominant alleles for normal wing development. The female fruit fly has vestigial wings, indicating she carries two recessive alleles for this trait, as vestigial wings are the result of a recessive genetic condition. When these two individuals are crossed, all of their progeny will inherit one allele from the male (the dominant allele for wild-type wings) and one allele from the female (the recessive allele for vestigial wings). Since the male is homozygous dominant, all the offspring will receive a dominant allele for wings from him. Consequently, all female progeny produced from this cross will express the dominant phenotype of wild-type wings, as the dominant allele completely masks the effect of the recessive allele received from the mother. Therefore, 100% of the female progeny will exhibit wild-type wings. This understanding is essential in genetics, as it highlights the principles of dominance and genotype interactions when examining inheritance patterns.

Let's talk genetics! Specifically, let’s explore how a couple of fruit flies can teach us a lot about dominant and recessive traits. If you've ever scratched your head at the idea of crossing a homozygous dominant male fruit fly with a vestigial wing female, you're not alone. It might sound a bit tricky, but I promise it can be straightforward and even fun.

Imagine a male fruit fly that sports those stunning wild-type wings—let’s call him Charlie. He's got it made in the shade because he carries not one, but two dominant alleles for those gorgeous wings! On the flip side, we have a female fruit fly named Francesca. She’s a bit less decorated, sporting vestigial wings, which happen because she carries two recessive alleles for her wing trait. In simpler terms, her gene deck is a little stacked against her!

So, what happens when Charlie and Francesca tie the knot? Well, they get together and their progeny starts to come into the world. Now, you might be wondering: how’s this whole gene-sharing situation going to pan out? Here’s where things get interesting. Each offspring is going to inherit one allele from dad (the dominant wild-type) and one from mom (the recessive vestigial wing). Since Charlie is sooo locked in with those dominant alleles, every kiddo flies out with at least one wild-type allele.

Now, let’s see what that means for their female progeny. This is the juicy part: because all their female offspring will receive Charlie's dominant allele, they will all exhibit wild-type wings! Yep, you heard it right—100% of the female progeny are going to have those fab wild-type wings, completely masking the effect of Francesca's vestigial alleles.

This little exploration isn’t just about fruit flies—it shines a light on key genetic principles that form the backbone of inheritance patterns. It illustrates how dominance and recessive traits work, which is crucial if you’re delving into the world of genetics. Who knew a fruit fly could hold such educational power?

Understanding why traits express themselves is fundamental not only in fruit flies but in all living organisms. As we think through these concepts, it makes you appreciate the remarkable diversity of life around us. And let’s be honest, there’s something exhilarating about grasping how traits are passed down, like a biological game of tag—only way cooler! So, keep that curiosity alive! Who knows where your interest in genetics might take you next? From the tiny fruit fly to the complexities of human genetics, every twist and turn reveals more about the blueprint of life.