1. Long wings (L) in fruit flies is dominant to short wings (l). If you had a fruit fly with long wings, what mating would you set up to test if it was LL or Ll genotype?
2. Jane's mother died of Huntington's disease (a dominant disorder): Jane says she is not worried about getting the disease because she knows her dad does not have the disease. How would you explain to Jane her risk of the disease?
3. When the parents are *always* normal , but their children are affected by a disease, does this indicate transmission via the dominant or the recessive? I think that it is the recessive.
1. Mate with an Ll. If about 25% offspring are short-winged, it is also Ll. If none, it is LL.
2. If dominant, only one gene is needed for the disorder. If mom is heterozygous, her chances are 50%, if homozygous, certainty.
3. Right. If both parents are only carriers for the recessive gene, they will not have the disease, but the children will have a 25% chance of getting it.
I'm looking for an answer to this question
In fruit flies the allele for long wings (L) is dominant and the allele for short wings (l) is recessive. What is the likely genotype of a fruit fly with long wings?
Either LL or Ll
Either Ll or ll
Only LL
Only ll
1. To test if the fruit fly with long wings is LL or Ll genotype, you would set up a mating with a fruit fly with short wings (ll genotype).
If the fruit fly with long wings is LL genotype, all the offspring from the mating will have long wings because LL is dominant over ll.
If the fruit fly with long wings is Ll genotype, you would expect a 1:1 ratio of offspring with long wings (Ll genotype) and short wings (ll genotype) because Ll is heterozygous and ll is homozygous recessive.
By observing the phenotypes (long or short wings) of the offspring, you can determine the genotype of the fruit fly with long wings.
2. Huntington's disease is caused by a dominant gene, meaning that if an individual has just one copy of the gene from either parent, they will develop the disease. Jane's statement that she is not worried about getting the disease because her dad does not have it is incorrect.
If Jane's mother had Huntington's disease, it means that she had a dominant gene for the disorder. Since the disease is dominant, there is a 50% chance that Jane inherited the dominant gene from her affected mother.
Even if Jane's dad does not have the disease, there is still a chance that he carries a copy of the gene without showing symptoms. If he does carry the gene, Jane would have a 50% chance of inheriting it from her dad as well.
Therefore, Jane's risk of developing Huntington's disease would depend on whether she has inherited the dominant gene from either parent.
3. When the parents are always normal, but their children are affected by a disease, it suggests transmission via a recessive gene.
For a recessive trait or disease to be expressed, an individual must inherit two copies of the recessive gene, one from each parent. If both parents are normal, it means they do not carry the recessive gene and therefore cannot pass it on to their children.
However, if both parents carry a single copy of the recessive gene without showing any symptoms, they are considered carriers. When two carriers have children, there is a 25% chance that their child will inherit two copies of the recessive gene and express the disease phenotype.
In summary, the presence of a disease in the children of two normal parents suggests transmission via a recessive gene.
1. To determine the genotype of a fruit fly with long wings, you would need to set up a mating with a fruit fly that has short wings. This is because the genotype of a fruit fly with short wings is always ll. By observing the phenotypes of the offspring, you can deduce the genotype of the long-winged fruit fly.
If the offspring have all long wings, then the genotype of the long-winged fruit fly is LL, as both parents would have contributed a dominant allele for long wings (Ll x ll = LL). However, if some offspring have short wings, then the genotype of the long-winged fruit fly is Ll, as it would have passed on the recessive allele for short wings (Ll x ll = Ll).
2. Jane's risk of inheriting Huntington's disease is dependent on whether her father carries the disease-causing allele or not. If Huntington's disease is a dominant disorder and Jane's mother had the disease, it means she carried at least one copy of the disease-causing allele (H). If her father does not have the disease, it could be because he either does not carry the disease-causing allele or he carries it but does not exhibit the symptoms.
To determine Jane's risk, it would be necessary to know her father's genotype. If her father does not carry the disease-causing allele (HH), then Jane would not be at risk of inheriting Huntington's disease. However, if her father carries the disease-causing allele (Hh or HH), then Jane would have a 50% chance of inheriting the allele and eventually developing the disease.
It is crucial for Jane to discuss this with her father and possibly undergo genetic testing to ascertain her risk accurately.
3. In the situation you described, when parents are always normal but their children are affected by a disease, it suggests that the disease is likely transmitted through a recessive inheritance pattern. This is because for a recessive disorder to manifest, an individual needs to inherit two copies of the disease-causing allele, one from each parent.
If either of the parents carried a single copy of the disease-causing allele but remained unaffected, they would be considered carriers. When two carriers come together and have children, there is a chance that their children will inherit two copies of the allele and consequently be affected by the disease.
On the other hand, if the disease was transmitted via the dominant pattern, the affected individuals would typically have at least one affected parent. This is because in the dominant inheritance pattern, an affected individual only needs to inherit one copy of the disease-causing allele from either parent to be affected themselves.
Therefore, based on the information provided, it is more likely that the disease in question is transmitted via the recessive inheritance pattern.