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

1. Introduction to Genetics

Fundamentals of Genetics

Genetics

1. Introduction to Genetics

Fundamentals of Genetics

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2:07 minutes

Problem 24b

Textbook Question

Suppose a genotype for a protein-producing gene can have any combination of three alleles, A₁, A₂, and A₃.
Each allele produces a protein with a distinct electrophoretic mobility. Allele A₁ has the highest electrophoretic mobility, A₃ has the lowest electrophoretic mobility, and the electrophoretic mobility of A₂ is intermediate between them. Draw the appearance of gel electrophoresis protein bands for each of the possible genotypes. Be sure to label each lane of the gel with the corresponding genotype.

Verified step by step guidance

Understand the problem: The question involves analyzing the electrophoretic mobility of proteins produced by three alleles (A₁, A₂, A₃) and visualizing the results on a gel electrophoresis. Each allele produces a protein with distinct mobility: A₁ has the highest mobility, A₂ is intermediate, and A₃ has the lowest mobility.

List all possible genotypes: Since there are three alleles (A₁, A₂, A₃), the possible genotypes include homozygous combinations (A₁A₁, A₂A₂, A₃A₃) and heterozygous combinations (A₁A₂, A₁A₃, A₂A₃).

Determine the protein bands for each genotype: For homozygous genotypes (e.g., A₁A₁), only one protein band will appear, corresponding to the mobility of the allele. For heterozygous genotypes (e.g., A₁A₂), two protein bands will appear, one for each allele's mobility.

Draw the gel electrophoresis: Label each lane with the genotype. For each genotype, place bands at positions corresponding to the electrophoretic mobility of the proteins. For example, A₁A₁ will have a single band at the highest mobility position, A₃A₃ will have a single band at the lowest mobility position, and A₁A₂ will have two bands, one at the highest and one at the intermediate mobility positions.

Review and label the gel: Ensure that all lanes are labeled with the correct genotypes and that the positions of the bands accurately reflect the electrophoretic mobility of the proteins. The gel should visually represent the distinct mobilities of proteins produced by each allele combination.

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Key Concepts

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

Alleles and Genotypes

Alleles are different versions of a gene that can exist at a specific locus on a chromosome. In this scenario, the alleles A₁, A₂, and A₃ represent variations of a protein-producing gene. A genotype refers to the specific combination of alleles an individual possesses, which can influence the phenotype, or observable traits, such as protein production and mobility in gel electrophoresis.

Electrophoretic Mobility

Electrophoretic mobility is a measure of how quickly a protein moves through a gel matrix when an electric field is applied. This movement is influenced by the protein's size, charge, and shape. In the context of the question, each allele produces a protein with distinct mobility, allowing for differentiation between genotypes based on the position of bands in the gel.

Gel Electrophoresis

Gel electrophoresis is a laboratory technique used to separate macromolecules, such as proteins or nucleic acids, based on their size and charge. In this process, samples are loaded into a gel matrix, and an electric current is applied, causing the molecules to migrate. The resulting pattern of bands can be analyzed to determine the presence of specific alleles and their corresponding genotypes.

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Textbook Question

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