Table of contents

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
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

21. Population Genetics

Hardy Weinberg

Genetics

21. Population Genetics

Hardy Weinberg

Previous problemNext problem

1:05 minutes

Problem 8

Textbook Question

In a population where only the total number of individuals with the dominant phenotype is known, how can you calculate the percentage of carriers and homozygous recessives?

Verified step by step guidance

span>Step 1: Understand the problem context. We are dealing with a population where we know the number of individuals with the dominant phenotype. This implies we are working with a trait that follows Mendelian inheritance, where the dominant phenotype can be expressed by either homozygous dominant (AA) or heterozygous (Aa) genotypes.

span>Step 2: Define the variables. Let p represent the frequency of the dominant allele (A) and q represent the frequency of the recessive allele (a). According to the Hardy-Weinberg principle, the sum of these allele frequencies is 1, i.e., p + q = 1.

span>Step 3: Use the Hardy-Weinberg equation. The equation p^2 + 2pq + q^2 = 1 represents the frequencies of the genotypes in the population, where p^2 is the frequency of homozygous dominant individuals (AA), 2pq is the frequency of heterozygous individuals (Aa), and q^2 is the frequency of homozygous recessive individuals (aa).

span>Step 4: Relate the known data to the equation. Since we know the total number of individuals with the dominant phenotype, this includes both homozygous dominant (p^2) and heterozygous (2pq) individuals. Therefore, the frequency of the dominant phenotype is p^2 + 2pq.

span>Step 5: Calculate the unknowns. To find the percentage of carriers (heterozygous, Aa) and homozygous recessives (aa), you need to solve the system of equations: p^2 + 2pq = frequency of dominant phenotype and p + q = 1. From these, you can derive q^2 for homozygous recessives and 2pq for carriers.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Phenotype and Genotype

Phenotype refers to the observable traits of an organism, such as physical appearance, while genotype refers to the genetic makeup that determines these traits. In this context, the dominant phenotype can be expressed by both homozygous dominant (AA) and heterozygous (Aa) genotypes, whereas the homozygous recessive (aa) genotype corresponds to the recessive phenotype.

Hardy-Weinberg Principle

The Hardy-Weinberg Principle provides a mathematical framework for understanding genetic variation in a population. It states that allele and genotype frequencies will remain constant from generation to generation in the absence of evolutionary influences. This principle can be used to calculate the frequencies of different genotypes based on the known frequencies of phenotypes.

Carrier Frequency

Carrier frequency refers to the proportion of individuals in a population who carry one copy of a recessive allele but do not express the recessive phenotype. In the context of the question, calculating the percentage of carriers involves determining the frequency of heterozygous individuals (Aa) based on the total number of individuals with the dominant phenotype and the known frequency of homozygous recessives.

Watch next

Master Hardy Weinberg with a bite sized video explanation from Kylia

Start learning

Related Videos

Related Practice

Textbook Question

Consider rare disorders in a population caused by an autosomal recessive mutation. From the frequencies of the disorder in the population given, calculate the percentage of heterozygous carriers:

0.01

460

views

Textbook Question

Consider rare disorders in a population caused by an autosomal recessive mutation. From the frequencies of the disorder in the population given, calculate the percentage of heterozygous carriers:

0.09

385

views

Textbook Question

Consider rare disorders in a population caused by an autosomal recessive mutation. From the frequencies of the disorder in the population given, calculate the percentage of heterozygous carriers:

0.000081

326

views

Textbook Question

Consider rare disorders in a population caused by an autosomal recessive mutation. From the frequencies of the disorder in the population given, calculate the percentage of heterozygous carriers:

0.0064

347

views

Textbook Question

The ability to taste the bitter compound phenylthiocarbamide (PTC) is an autosomal dominant trait. The inability to taste PTC is a recessive condition. In a sample of 500 people, 360 have the ability to taste PTC and 140 do not. Calculate the frequency of the recessive allele.

Consider a population in which the frequency of allele A is p = 0.7 and the frequency of allele a is q = 0.3 and where the alleles are codominant. What will be the allele frequencies after one generation if the following occurs?

w_AA= 0.8, w_Aa= 1, w_aa= 0.8

574

views

Show more practices

Download the Mobile app

Privacy

Do not sell my personal information

Accessibility

Patent notice

Sitemap