1. Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. They identify the gene responsible for toxin production. The dominant allele (T) codes for an enzyme that makes the toxin, and the recessive allele (t) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The genotypes of all individuals in the population are determined (TT = 0.56; Tt = 0.28; tt = 0.16) and used to determine the actual allele frequencies in the population. Is this population in Hardy-Weinberg equilibrium? Calculate the T and t.
I already know the answer is "No, there are more homozygotes than expected", but I do not understand how to find this answer. SHOW WORK.
1. Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. They identify the gene responsible for toxin production. The dominant allele (T) codes for an enzyme that makes the toxin, and the recessive allele (t) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The genotypes of all individuals in the population are determined (TT = 0.56; Tt = 0.28; tt = 0.16) and used to determine the actual allele frequencies in the population. Is this population in Hardy-Weinberg equilibrium? Calculate the T and t.
I already know the answer is "No, there are more homozygotes than expected", but I do not understand how to find this answer. SHOW WORK.
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Problem B: Prairie Dog Population Genetics
A relatively stable population of Black-footed Prairie Dogs (70,000 individuals) lives in a national park in
Saskatchewan, Canada. These creatures have various tones of brown fur, but may have brown or auburn tails.
Furthermore, tails may be of solid color (brown or auburn) or be tipped with white or black fur. Three alleles for
tail coloration exist in this population. These alleles include:
| Allele | Trait | Notes on Phenotype and Relationship to other Alleles |
| T | White Tip | Tail has white fur at tip. Completely dominant over t; codominant with T* |
| t | Black tip | Tail has black fur at tip. Codominant with T*; recessive to T |
| T* | Auburn tail | Background tail color is auburn when T* is present. Codominant with T or t |
The frequency of the (T) allele in this population is 0.28, and the frequency of the (t) is 0.4.
Answer each of the following. Show all of your work/calculations. Cite your rationale if appropriate.
1. List and describe all the possible genotypes and their respective phenotypes for this gene system in the
population.
2. Using the Hardy-Weinberg theorem, calculate the probable frequency of animals with the following
phenotypes in this population:
⢠White tipped tails
⢠Black tipped auburn tails
3. What is the expected combined frequency of individuals carrying the TT, TT* and Tt genotypes in this
population?
4. How many (number, not percentage) of the prairie dogs would you expect to have black tipped, auburn
tails? Explain.
5. In a different population of 10,000 prairie dogs (South Dakota, USA), only the T and t alleles are found. If
this group included only 400 animals with black tipped, brown tails, what is the probable number (not
frequency) of individuals that are homozygous dominant (TT) in this herd?
For simplicity, we will assume that golden manes (G) are dominant over black manes (g), and thick manes (T) are dominant over thin (t).(In reality, the inheritance of these traits is a lot more complex and lions exhibit a range of mane colours from golden to brown to dark brown to black â but here we will keep it simple.)
(i) The frequency of black manes: 0.204
(ii) The frequency of golden manes: 0.795
(i) The frequency of thick manes: 0.343
(ii) The frequency of thin manes: 0.656
| Locus | Genotypes | Phenotypes |
| T (Mane Thickness) | TT | Thick |
| Tt | Thick | |
| tt | Thin | |
| G (Mane Colour) | GG | Golden |
| Gg | Golden | |
| gg | Black |
Assuming the African population is in Hardy-Weinberg equilibrium for the two loci, what are the observed frequencies of each allele (G, g, T and t) in this lion population?
Round your answer to three decimal places and submit your answer in the correct format (e.g. 0.062).
(a) Frequency of the G allele = ---------------------------
(b) Frequency of the g allele = ----------------------------
(c) Frequency of the T allele =----------------------------
(d) Frequency of the t allele = ----------------------
Based on the allele frequencies you calculated above (in Question 2), answer the following questions.Round your answers to the nearest whole number (because you cannot have part of a lion!).
(a) Locus 1: Mane colour
(i) How many lions would you expect to be heterozygous for mane colour (i.e. Gg)? -----------------------------
(ii) How many lions would you expect to be homozygous dominant for mane colour (i.e. GG)? ----------------------
(iii) How many lions would you expect to be homozygous recessive for mane colour (i.e. gg)? ------------------
(b) Locus 2: Mane Thickness
(i) How many lions would you expect to be heterozygous for mane thickness (i.e. Tt)? --------------
(ii) How many lions would you expect to be homozygous dominant for mane thickness (i.e. TT)?--------------------
(iii) How many lions would you expect to be homozygous recessive for mane thickness (i.e. tt)? ----------------
