BIOA01H3 Chapter Notes - Chapter 21.2: Allele Frequency, Electrophoresis, Allele

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The proportion of a specified allele among all the alleles of a gene in a population. To understand patterns of genetic variation, we require information about allele frequencies. Allele frequency of allele x is the number of x"s present in the population divided by the total number of alleles heterozygotes. Given the genotype frequencies, the allele frequencies can also be determined. Allele frequencies of dominant x alleles and recessive x alleles provide a measure of genetic variation of one gene at a given population. Three ways to measure genotype and allele frequencies: Early population geneticists relied on observable traits and gel electrophoresis to measure. Measuring genetic variation through observable traits is simple. It is difficult (if not impossible) to make direct inferences from a phenotype to an number of genes underlying genotype. Traits that have simple sets of phenotypes often have complicated genotype. Separates segments of dna according to their size.

Related Questions

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 = ----------------------------

(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)? ----------------

coralbuffalo105

Q 1 â Manx cats are produced when a dominant allele is inherited for the Manx gene (M). Inheritance of two dominant alleles, however, results in death of the fetus. Coat color in cats is determined by two alleles with incomplete dominance. BB produces black colored cats, Bb produces grey cats, and bb produces white cats. A grey Manx cat is mated with a white Manx. What proportion of the living offspring will be white Manx kittens? (3 points)

Q 2 â In goats, a beard is produced by an autosomal allele that is dominant in males and recessive in females. Weâll use the symbol B^b for the beard allele and B+ for the beardless allele. Another independently assorting autosomal allele that produces a black coat (W) is dominant over the allele for white coat (w). Give the phenotypes and their proportions expected for the following cross: B⁺B⁺Ww male Ã B^bB^bWw female (2 points)

Q 3 â E. W. Lindstrom crossed two corn plants with green seedlings and obtained the following progeny: 3583 green seedlings, 853 virescent-white seedlings, and 260 yellow seedlings.

Give the genotypes for the green, virescent-white, and yellow seedlings

Explain how color is determined in these seedlings (which genotype gives which phenotype). (3 points)

Q 4 â You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However the L allele is only 60% penetrant in both homozygotes and heterozygotes. In a population of 212 giraffes in an African nature preserve, 80 giraffes are either homozygous or heterozygous for the long ossicone allele (L). What proportion of offspring would you expect to exhibit the long ossicone phenotype? (2 points)

harlequinserval672

Hemoglobin and Fitness Instructions Directions: Neutral Evolution

1. Obtain 20 beans of two different colors (e.g., white and red). Count out 16 white and 4 red beans. The white beans represent the Hn allele and the red beans represent the Hs allele. This is the genetic makeup of your starting population. (Note: You can use any objects that can readily be categorized into two groups, such as coins, colored rocks, or paper clips.)

2.Calculate the frequency of both alleles [f(Hn) and f(Hs)] and record them in Table 1. In our experiment frequency is a measure of how many copies of a given allele exist in the gene pool (i.e., a proportion). Use decimal values. â¨

3.Arrange the beans into pairs. These pairs represent the genotype of each of 10 individuals in the population. Record the number of individuals with each genotype [f(Hn Hn), f(Hn Hs), and f(HsHs)] in Table 1. â¨

4.Now imagine that the individuals are living and reproducing with each individual reproducing at the same rate (i.e., all individuals produce two copies of each of their alleles into the next generation). Obtain enough beans to represent the next generationâ the offspring generationâand then let the parental generation âdieâ. â¨

5.Calculate the frequency of each allele in the offspring generation and record it in Table 1. â¨

Answer the questions that follow in Table 1. â¨

Table 1

	f(HnHn)	f(HnHs)	f(HsHs)	f(Hn)	f(Hs)
oiginal generation
offspring generation

Answer the following questions to help you understand the exercise:

What happened to the frequency of the common allele? â¨

What happened to the frequency of the rare allele? â¨

What happened to the frequency of the common and rare alleles when the starting frequencies were different from yours

What happens to allele frequencies from one generation to the next if there are no evolutionary forces acting on the population? â¨

greyotter669

BIOA01H3 Chapter Notes - Chapter 21.2: Allele Frequency, Electrophoresis, Allele

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