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

2. Mendel's Laws of Inheritance

Monohybrid Cross

Genetics

2. Mendel's Laws of Inheritance

Monohybrid Cross

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2:23 minutes

Problem 12d

Textbook Question

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:
3/4 brown : 1/4 yellow

Verified step by step guidance

Step 1: Begin by analyzing the progeny ratio provided in the problem. The ratio of 3/4 brown to 1/4 yellow suggests a Mendelian inheritance pattern consistent with a single gene exhibiting dominance and recessiveness. Brown is likely the dominant phenotype, and yellow is the recessive phenotype.

Step 2: Recall that a 3:1 phenotypic ratio typically arises from a monohybrid cross where both parents are heterozygous for the gene in question. Represent the dominant allele as 'B' (brown) and the recessive allele as 'b' (yellow). The heterozygous genotype would be 'Bb'.

Step 3: Set up a Punnett square to confirm the expected progeny ratios. Place the alleles of one parent (B and b) along the top of the square and the alleles of the other parent (B and b) along the side. Fill in the squares by combining the alleles from the top and side.

Step 4: Analyze the Punnett square results. You should observe that the genotypes of the progeny are distributed as follows: 1/4 BB (homozygous dominant), 1/2 Bb (heterozygous), and 1/4 bb (homozygous recessive). The phenotypes will be 3/4 brown (BB and Bb) and 1/4 yellow (bb).

Step 5: Conclude that the parents must both have the genotype 'Bb' (heterozygous) to produce the observed 3:1 phenotypic ratio in the progeny. Their phenotypes would both be brown, as the dominant allele masks the recessive allele in heterozygous individuals.

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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 trait. In this context, it is important to understand how different combinations of alleles can lead to the observed phenotypes in progeny. For example, in a simple Mendelian trait, the genotype can be homozygous dominant, homozygous recessive, or heterozygous, influencing the traits expressed in the offspring.

Phenotype

Phenotype is the observable physical or biochemical characteristics of an organism, determined by both its genotype and environmental factors. In this case, the phenotypes of the progeny are brown and yellow, which are the visible traits resulting from the underlying genotypes of the parents. Understanding the relationship between genotype and phenotype is crucial for predicting the traits of offspring.

Mendelian Inheritance

Mendelian inheritance is the set of principles related to the transmission of genetic traits from parents to offspring, based on Gregor Mendel's experiments with pea plants. The ratios of phenotypes in the progeny, such as 3:1 in this case, suggest a typical monohybrid cross where one trait is dominant over another. This concept helps in predicting the expected ratios of offspring based on the genotypes of the parents.

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Textbook Question

A male mouse from a true-breeding strain of hyperactive animals is crossed with a female mouse from a true-breeding strain of lethargic animals. (These are both hypothetical strains.) All the progeny are lethargic. In the F₂ generation, all offspring are lethargic. What is the best genetic explanation for these observations? Propose a cross to test your explanation.

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Textbook Question

Black skin color is dominant to pink skin color in pigs. Two heterozygous black pigs are crossed.

If these pigs produce a total of three piglets, what is the probability that two will be pink and one will be black?

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Textbook Question

Black skin color is dominant to pink skin color in pigs. Two heterozygous black pigs are crossed.

What is the probability that the first and second offspring will have black skin?

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Textbook Question

Black skin color is dominant to pink skin color in pigs. Two heterozygous black pigs are crossed.

What is the probability that their offspring will have pink skin?

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Textbook Question

A male mouse with brown fur color is mated to two different female mice with black fur. Black female 1 produces a litter of 9 black and 7 brown pups. Black female 2 produces 14 black pups.

Choose symbols for each allele, and identify the genotypes of the brown male and the two black females.

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Textbook Question

A male mouse with brown fur color is mated to two different female mice with black fur. Black female 1 produces a litter of 9 black and 7 brown pups. Black female 2 produces 14 black pups.

What is the mode of inheritance of black and brown fur color in mice?

416

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Textbook Question

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:

27/64 brown : 16/64 albino : 9/64 yellow : 9/64 black : 3/64 cream

412

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Textbook Question

Using the information provided in Problems 10 and 11, determine the genotype and phenotype of parents that produce the following progeny:

3/8 black : 3/8 cream : 2/8 albino

608