In a random mating population of Drosophila, 5% of the flies have black bodies (encoded by recessive b) and 95% have brown bodies (encoded by B). Assuming Hardy-Weinberg equilibrium what is the allele frequency of B in the population?

Okay, so in this question we're actually going to have to use our calculators and, our Hardy Weinberg formulas in order to calculate the allele frequency of this dominant allele in a population. So the question says, we have fruit flies, 5% of them are black and black is homozygous recessive. Plus 5%. Whereas, 95% of them have brown bodies, which have, which at least have at least one allele of the dominant allele be dominant. And so, okay, we're assuming Hardy Weinberg equilibrium. It means we can use the formula. What's the allele frequency of the dominant allele in the population? So that is, you know, how what's the allele frequency including homozygous recessive and heterozygous? So what's that frequency? So first thing we know so what is this? So the dominant allele is represented by p. Right? And Hardy Weinberg, that represents the dominant allele. So this is what we're calculating. We're trying to calculate p. But what we have is our recessive information, specifically, q squared. Right? Because we have 2 recessive alleles. And we know that equals 5% and if we're putting that in a decimal point format, 0.05. So with q squared, how do we solve for p? Well, the easiest way is actually to take the square root of q squared because that equals q. And using q, we can very easily determine p. So if we take the square root of q, which is 0.05, what do we get? We get 0.22 and that is our q. Now, there's a really important formula here. Right? We do p plus q equals 1. We have q, so we have p plus 0.22 equals 1. So now, we need to solve for p, and we do that by subtracting 0.22 on each side. So then we get what? P equals 1 minus 0.22. And so what that is, is it's, 1 minus 0.22 is p equals, 1 minuteus or p equals 0.78. It can also be 77 depending on how many decimal points you use. But 0.78. And so, that is what we're looking for. P represents the allele frequency of the dominant allele b in the population and so the answer that's closest to the answer we got is a. And so with that, we could move on. But I want you to take a second and say, well, how would I knowing p and q, how would I solve for things like the homozygous, homozygous dominant, which would be p, squared, or heterozygous, which would be 2pq, or homozygous recessive, which was given to us, but you get my point. So using these values, you can determine anything, any of these frequencies in the population. So with that, let's move on.

In a random mating population of Drosophila, 5% of the flies have...

1. Introduction to Genetics51m

2. Mendel's Laws of Inheritance3h 37m

3. Extensions to Mendelian Inheritance2h 41m

4. Genetic Mapping and Linkage2h 28m

5. Genetics of Bacteria and Viruses1h 21m

6. Chromosomal Variation1h 48m

7. DNA and Chromosome Structure56m

8. DNA Replication1h 10m

9. Mitosis and Meiosis1h 34m

10. Transcription1h 0m

11. Translation58m

12. Gene Regulation in Prokaryotes1h 19m

13. Gene Regulation in Eukaryotes44m

14. Genetic Control of Development44m

15. Genomes and Genomics1h 50m

16. Transposable Elements47m

17. Mutation, Repair, and Recombination1h 6m

18. Molecular Genetic Tools19m

19. Cancer Genetics29m

20. Quantitative Genetics1h 26m

21. Population Genetics50m

22. Evolutionary Genetics29m

My Courses

Chemistry

Biology

Math

Physics

Business

Social Sciences

Programming

Product & Marketing

In a random mating population of Drosophila, 5% of the flies have black bodies (encoded by recessive b) and 95% have brown bodies (encoded by B). Assuming Hardy-Weinberg equilibrium what is the allele frequency of B in the population?