Biology: Variation & Population Genetics, Hardy-Weinberg

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Questions and Answers

Which of the following is a condition for Hardy-Weinberg equilibrium?

  • Mutation
  • Small population size
  • Random mating (correct)
  • Natural selection

Genetic variation in a population will remain constant from one generation to the next if the conditions for Hardy-Weinberg equilibrium are met.

True (A)

If a population is NOT in Hardy-Weinberg equilibrium, what process is likely occurring?

  • Evolution (correct)
  • Genetic redundancy
  • Stasis
  • Gene conservation

What is the term for the movement of genes from one population to another?

<p>Gene flow (migration) (C)</p> Signup and view all the answers

Inbreeding is an example of random mating, which supports Hardy-Weinberg equilibrium.

<p>False (B)</p> Signup and view all the answers

The MN blood group system has two alleles, M and N, which code for a ______ on the surface of red blood cells.

<p>glycoprotein</p> Signup and view all the answers

In the context of population genetics, what do alleles M and N represent in the MN blood group system?

<p>Variations of the same gene (D)</p> Signup and view all the answers

What data was collected from individuals in the Philippines to study the MN locus?

<p>blood samples and questionnaire</p> Signup and view all the answers

Which of the following is NOT typically included in a questionnaire when studying population genetics?

<p>Personal food preferences (B)</p> Signup and view all the answers

The observed genotype frequencies for the MN locus are always the same across different populations.

<p>False (B)</p> Signup and view all the answers

How is the frequency of the M allele (denoted as $p$) calculated using genotype frequencies?

<p>$f_{MM} + f_{MN}/2$ (D)</p> Signup and view all the answers

If the frequency of the M allele ($p$) is 0.6, what is the frequency of the N allele ($q$)?

<p>0.4</p> Signup and view all the answers

In the Hardy-Weinberg equation, $p^2 + 2pq + q^2 = 1$, what does the term $2pq$ represent?

<p>Frequency of the heterozygous genotype (B)</p> Signup and view all the answers

If observed genotype frequencies deviate significantly from expected Hardy-Weinberg frequencies, the population is considered to be in equilibrium.

<p>False (B)</p> Signup and view all the answers

Which of the following factors can cause a population to deviate from Hardy-Weinberg equilibrium?

<p>Natural selection (B)</p> Signup and view all the answers

According to the Hardy-Weinberg principle, the sum of allele frequencies for all alleles at a locus in a population must equal ______.

<p>1</p> Signup and view all the answers

How can comparing observed genotype frequencies with expected Hardy-Weinberg frequencies help in understanding a population?

<p>Determining the presence of evolutionary forces (C)</p> Signup and view all the answers

If a population is in Hardy-Weinberg equilibrium, it means that the allele frequencies are changing rapidly from one generation to the next.

<p>False (B)</p> Signup and view all the answers

What is the primary consequence of isolation and inbreeding in small populations?

<p>Populations not in Hardy-Weinberg equilibrium (D)</p> Signup and view all the answers

Within a population, the combination of all the genes (including all the different alleles) comprises the ______.

<p>gene pool</p> Signup and view all the answers

Which scenario would likely result in a population NOT being in Hardy-Weinberg equilibrium?

<p>Environmental changes favoring certain traits (B)</p> Signup and view all the answers

Migration prevents changes in allele frequencies of a population.

<p>False (B)</p> Signup and view all the answers

Which of the following equations correctly represents the Hardy-Weinberg principle for allele frequencies?

<p>$p + q = 1$ (D)</p> Signup and view all the answers

What does it mean for a population to be in 'equilibrium' regarding its genetic makeup?

<p>Allele and genotype frequencies remain constant from generation to generation.</p> Signup and view all the answers

What information is needed to apply the Hardy-Weinberg equation to a population?

<p>Allele or genotype frequencies (B)</p> Signup and view all the answers

Under Hardy-Weinberg equilibrium, the allele frequencies in a population change predictably over time.

<p>False (B)</p> Signup and view all the answers

In the context of the MN blood group in the Philippines, what might cause the observed frequencies to differ from Hardy-Weinberg expectations?

<p>Random mating within specific ethnic groups (D)</p> Signup and view all the answers

If observed genotype frequencies are higher than expected under Hardy-Weinberg equilibrium, it suggests that ______ selection may be occurring.

<p>natural</p> Signup and view all the answers

According to Hardy-Weinberg, what is the relationship between allele and genotype frequencies in a population?

<p>Allele frequencies determine genotype frequencies (D)</p> Signup and view all the answers

The Hardy-Weinberg principle is most accurate for small, rapidly evolving populations.

<p>False (B)</p> Signup and view all the answers

Match these terms with their descriptions:

<p>Hardy-Weinberg Equilibrium = A principle stating that allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences. Allele Frequency = The relative proportion of an allele at a particular locus in a population. Gene Flow = The transfer of genetic variation from one population to another. Natural Selection = The process by which individuals with certain heritable traits survive and reproduce at a higher rate than other individuals in a population.</p> Signup and view all the answers

Which condition, if violated, is most likely to cause significant and rapid deviations from Hardy-Weinberg equilibrium in a small population?

<p>Random mating (D)</p> Signup and view all the answers

How can understanding the Hardy-Weinberg equilibrium relate to studying genetic diseases in populations?

<p>Help determining if the genetic diseases are evolving</p> Signup and view all the answers

What is indicated when the observed frequency of a recessive homozygous genotype is significantly higher than projected by the Hardy-Weinberg equilibrium?

<p>Natural selection may be favoring the recessive trait (D)</p> Signup and view all the answers

If the two areas of same colors appear closer to the same height, that population should judged to be in Hardy-Weinberg equilibrium.

<p>True (A)</p> Signup and view all the answers

Which condition is vital in allowing populations to stay in Hardy-Weinberg equilibrium?

<p>Large population with truly random mixing (A)</p> Signup and view all the answers

What is the purpose of comparing HW with non-HW graph values?

<p>To determine if genetic drift is present in a population</p> Signup and view all the answers

Under HW, what would a bar that barely has a horizontal top mean?

<p>A very small number for the population (C)</p> Signup and view all the answers

A population in HW in never impacted by events.

<p>False (B)</p> Signup and view all the answers

Why is it that the ethnic regions are often an important role in maintaining Hardy-Weinberg?

<p>Ethnic groups often inbreed and isolate, preserving values (A)</p> Signup and view all the answers

What does a chromosome represent?

<p>Multiple genes linked together</p> Signup and view all the answers

If most areas are the same color, what does that imply for ethnic diversity?

<p>Little to no Ethnic or Genetic Diversity (A)</p> Signup and view all the answers

Flashcards

Hardy-Weinberg Equilibrium

States that genetic variation will remain constant from one generation to the next if certain conditions are met.

Condition 1 for H-W Equilibrium

Very large population size to minimize genetic drift.

Condition 2 for H-W Equilibrium

No natural selection biasing allele frequencies.

Condition 3 for H-W Equilibrium

No new alleles being added to the pool.

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Condition 4 for H-W Equilibrium

No migration (gene flow) in or out of the population.

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Condition 5 for H-W Equilibrium

Random mating (no inbreeding) to keep allele combinations random.

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Evolution occurs when...

When the conditions for Hardy-Weinberg equilibrium are NOT met.

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Alleles

Variations of the same gene coding for different proteins.

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"p" in H-W Equations

The frequency of the dominant allele in a population.

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"q" in H-W Equations

The frequency of the recessive allele in a population.

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Allele Frequency Equation

p + q = 1, showing that the sum of allele frequencies is 100%.

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p² in H-W Equations

The frequency of homozygous dominant individuals (AA).

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2pq in H-W Equations

The frequency of heterozygous individuals (Aa).

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q² in H-W Equations

The frequency of homozygous recessive individuals (aa).

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Genotype Frequency Equation

p² + 2pq + q² = 1, showing the sum of genotype frequencies totals 100%.

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Population not in equilibrium.

When observed genotype frequencies differ significantly from expected Hardy-Weinberg (HW) frequencies.

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Population is in equilibrium.

When observed genotype frequencies align closely with what's expected via Hardy-Weinberg (HW) predictions.

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Population Size and Equilibrium

Small, isolated groups are more susceptible to deviations from H-W equilibrium.

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Karyotype

A visual representation of all chromosomes within a cell.

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Study Notes

  • Integrating Concepts in Biology is about Variation and Population Genetics
  • Section 16.2 is about using population genetic information to predict evolution
  • Biology Learning Objectives are to explain the Hardy-Weinberg equilibrium, evaluate its application, and determine if a population is evolving using the equation

Hardy – Weinberg Equilibrium

  • States that genetic variation in a population will remain constant from one generation to the next if the following conditions are met:
    • Population is very large
    • No natural selection
    • No mutation
    • No migration (gene flow)
    • Random mating (no inbreeding)
  • If these conditions are not met, the Allele frequencies will change resulting in evolution

Karyotype

  • There are two copies of every chromosome, one from the mother and one from the father
  • There are 2 alleles in the population for the blood group MN
  • The gene codes for a glycoprotein on the surface of red blood cells
    • Glycoprotein is coded by allele M
    • Glycoprotein coded by allele N
  • Alleles are variations of the same gene
  • Many genes code for proteins

MN Locus in Several Populations

  • 500 individuals were selected from populations in the Philippines along a north-south gradient
  • Blood samples were collected
  • A questionnaire was administered asking about place of birth, ethnic identity, and migration of individuals

Observed genotype frequencies of the MN genetic locus in Philippine populations

  • In Isabela, the frequency of MM = 0.73, MN = 0.12, and NN = 0.15
  • Frequency of M allele (denoted p) is fMM + fMN/2 which is 0.73 + 0.12/2 = 0.79
  • The frequency of N allele (denoted q) is fNN + MN/2 = 0.15 + 0.12/2 = 0.21
  • In Manilla, the frequency of MM = 0.26, MN = 0.52, and NN = 0.22
  • The frequency of M allele (denoted p) is fMM + fMN/2 = 0.26 + 0.52/2 = 0.52
  • The frequency of N allele (denoted q) is fNN + fMN/2 = 0.22 + 0.52/2 = 0.48
  • In Cebu, the frequency of MM = 0.36, MN = 0.59, and NN = 0.05
  • The frequency of M allele (denoted p) is fMM + fMN/2 = 0.36 + 0.59/2 = 0.655
  • The frequency of N allele (denoted q) is fNN + fMN/2 = 0.05 + 0.59/2 = 0.345
  • There is no north to south trend

Hardy – Weinberg Equilibrium Equation

  • Dominant allele frequency = p
  • Recessive allele frequency = q
  • Genotype frequencies:
    • AA = p2
    • Aa = 2pq
    • aa = q2
  • Important Equations
    • p + q = 1 (Allele frequencies)
    • p² + 2pq + q² = 1 (Genotype frequencies)
  • MN Blood group
    • M + N = 1
    • M² + 2MN + N2

Example

  • If the frequency of the M allele in populations is 0.79, then the frequency of the N allele is ___ according to Hardy-Weinberg
  • The frequency of the MM genotype is ___
  • The frequency of the MN genotype is ___
  • The frequency of the NN genotype is ___

Observed and HW genotype frequencies of the MN genetic locus in Philippine populations

  • If bars of a similar color are different heights, the population is judged to NOT be in Hardy-Weinberg equilibrium
  • If bars of a similar color are the same or similar height, then the population is judged to be in Hardy-Weinberg equilibrium
  • The population Isabela is judged to NOT be in Hardy-Weinberg equilibrium with a localized migration from nearby towns
  • Isolation and inbreeding in small populations can lead to populations not in HW equilibrium

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