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Questions and Answers
What defines an allele in genetic terms?
What defines an allele in genetic terms?
Which of the following is NOT an assumption of the Hardy-Weinberg model?
Which of the following is NOT an assumption of the Hardy-Weinberg model?
What does the equation $p + q = 1$ represent in the Hardy-Weinberg principle?
What does the equation $p + q = 1$ represent in the Hardy-Weinberg principle?
In a population, if the allele frequencies are $p = 0.46$ and $q = 0.54$, what is the frequency of heterozygous individuals?
In a population, if the allele frequencies are $p = 0.46$ and $q = 0.54$, what is the frequency of heterozygous individuals?
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If a population has 40 individuals with genotype HH, 45 with Hh, and 50 with hh, what is the frequency of the HH genotype?
If a population has 40 individuals with genotype HH, 45 with Hh, and 50 with hh, what is the frequency of the HH genotype?
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Using the Hardy-Weinberg principle, if 16% of the population is homozygous recessive (ss), what is the frequency of the homozygous dominant genotype (SS)?
Using the Hardy-Weinberg principle, if 16% of the population is homozygous recessive (ss), what is the frequency of the homozygous dominant genotype (SS)?
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What is the chi-square value calculated for the observed genotype counts compared to expected values?
What is the chi-square value calculated for the observed genotype counts compared to expected values?
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If 9% of a population is homozygous recessive for a trait, what percentage will be heterozygous and more resistant to a disease?
If 9% of a population is homozygous recessive for a trait, what percentage will be heterozygous and more resistant to a disease?
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If the total number of alleles in a population is calculated as 270, how is the frequency of allele H determined?
If the total number of alleles in a population is calculated as 270, how is the frequency of allele H determined?
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Study Notes
Definitions
- Allele: Variations of genes that determine specific traits.
- Locus: The specific location of a gene on a chromosome.
Hardy-Weinberg Principle
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Five Assumptions:
- Random mating occurs within the population.
- There are no mutations affecting alleles.
- No migration into or out of the population changes allele frequencies.
- Natural selection does not favor any particular genotype.
- The population is sufficiently large to avoid genetic drift.
Hardy-Weinberg Equilibrium
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Equations:
- Allele frequency: ( p + q = 1 )
- ( p ): Frequency of the dominant allele
- ( q ): Frequency of the recessive allele
- Genotype frequency: ( p^2 + 2pq + q^2 = 1 )
- ( p^2 ): Frequency of homozygous dominant genotype
- ( 2pq ): Frequency of heterozygous genotype
- ( q^2 ): Frequency of homozygous recessive genotype
- Allele frequency: ( p + q = 1 )
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Allele Frequency Calculation:
- Total number of alleles = Total number of chromosomes x 2
- Allelic frequencies calculated by dividing the number of dominant or recessive alleles by the total number of alleles.
Genotype Frequency Calculation
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Observed Genotypes:
- HH: 40
- Hh: 45
- hh: 50
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Total Genotypes: 135
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Genotype Frequencies:
- HH: ( 40/135 = 0.30 )
- Hh: ( 45/135 = 0.33 )
- hh: ( 50/135 = 0.37 )
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Allele Frequencies:
- Total alleles = ( 135 \times 2 = 270 )
- ( f(H) = (2 \times 40 + 45)/270 = 0.46 )
- ( f(h) = 0.54 ) (derived from ( p + q = 1 ))
Expected Genotype Frequencies under H-W Equilibrium
- Calculated from allele frequencies:
- HH: ( 0.2116 \times 135 = 28.57 )
- Hh: ( 0.4968 \times 135 = 67.07 )
- hh: ( 0.2916 \times 135 = 39.37 )
Chi-Square Test for H-W Equilibrium
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Formula:
( \chi^2 = \frac{(O - E)^2}{E} )- O: Observed number of genotypes
- E: Expected number of genotypes
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Calculations:
- For HH: ( \frac{(40 - 28.57)^2}{28.57} = 4.5 )
- For Hh: ( \frac{(45 - 67.07)^2}{67.07} = 7.2 )
- For hh: ( \frac{(50 - 39.37)^2}{39.37} = 2.8 )
- ( \chi^2 = 4.5 + 7.2 + 2.8 = 14.57 )
Sickle-Cell Anemia and Malaria Resistance
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Scenario: 9% (0.09) of a population has severe sickle-cell anemia (genotype ss).
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Calculating q:
- ( q^2 = 0.09 \rightarrow q = 0.3 )
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Calculating p:
- ( p + q = 1 \rightarrow p = 0.7 )
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Heterozygous Frequency:
- ( 2pq = 2 \times 0.7 \times 0.3 = 0.42 \rightarrow 42% )
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For a 16% (0.16) Population with ss:
- ( q^2 = 0.16 \rightarrow q = 0.4 )
- ( p + q = 1 \rightarrow p = 0.6 )
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Description
Test your understanding of the Hardy-Weinberg Principle and its assumptions. This quiz will cover key concepts like allele frequencies and genotype calculations. Perfect for students studying genetics or related fields.
