Ch. 2 - Transmission Genetics

Sanders - Genetic Analysis: An Integrated Approach 3rd Edition

Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook

Sanders 3rd Edition

Ch. 2 - Transmission Genetics

Problem 2

Chapter 2, Problem 2

For the cross BB×Bb, what is the expected genotype ratio? What is the expected phenotype ratio?

Verified step by step guidance

Step 1: Identify the genotypes of the parents in the cross. In this case, one parent is homozygous dominant (BB) and the other is heterozygous (Bb).

Step 2: Set up a Punnett square to determine the possible combinations of alleles. Place the alleles of one parent (BB) along the top and the alleles of the other parent (Bb) along the side.

Step 3: Fill in the Punnett square by combining the alleles from the top and the side for each box. This will give you the possible genotypes of the offspring.

Step 4: Count the frequency of each genotype in the Punnett square. For example, determine how many offspring are BB and how many are Bb.

Step 5: Determine the phenotype ratio by considering the dominant and recessive traits. Since B is dominant, both BB and Bb will express the dominant phenotype. Calculate the ratio of dominant to recessive phenotypes based on the genotypes.

Verified video answer for a similar problem:

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

Video duration:

Was this helpful?

Key Concepts

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

Genotype

Genotype refers to the genetic constitution of an organism, specifically the alleles it possesses for a particular gene. In the context of the cross BB×Bb, the genotypes involved are homozygous dominant (BB) and heterozygous (Bb). Understanding genotype is crucial for predicting the genetic outcomes of crosses.

Phenotype

Phenotype is the observable physical or biochemical characteristics of an organism, determined by both its genotype and environmental influences. In this case, the phenotype ratio will depend on the dominant and recessive traits expressed by the genotypes BB and Bb. Recognizing the relationship between genotype and phenotype is essential for interpreting the results of genetic crosses.

Punnett Square

A Punnett Square is a diagram used to predict the genotypic and phenotypic ratios of offspring from a genetic cross. By arranging the alleles of the parents (BB and Bb) in a grid, one can easily visualize the possible combinations and their frequencies. This tool is fundamental for understanding inheritance patterns and calculating expected ratios in genetic crosses.

Recommended video:

Guided course

18:27

Chi Square Analysis

Related Practice

Textbook Question

Compare and contrast the following terms:

Homozygous and Heterozygous

views

Textbook Question

Compare and contrast the following terms:

Monohybrid cross and Test cross

Textbook Question

Compare and contrast the following terms:

Dihybrid cross and Trihybrid cross

Textbook Question

For the cross Aabb × aaBb, what is the expected genotype ratio? What is the expected phenotype ratio?

Textbook Question

In mice, black coat color is dominant to white coat color. In the pedigree shown here, mice with a black coat are represented by darkened symbols, and those with white coats are shown as open symbols. Using allele symbols B and b, determine the genotypes for each mouse.

views

Textbook Question

A man, J.B., has a sister with autosomal recessive galactosemia (OMIM 230400), and his partner, S.B., has a brother with galactosemia. Galactosemia is a serious condition caused by an enzyme deficiency that prevents the metabolism of the sugar galactose. Neither J.B. nor S.B. has galactosemia, but they are concerned about the risk that a future child of theirs will have the condition. What is the probability their first child will have galactosemia?

views