Learning Guide: Mendel and the Gene Idea

Bill Activity #35

To Think About: In what ways does the chromosomal basis of inheritance provide an understanding of the patterns of transmission of genes from parent to offspring? How does simple Mendelian genetics explain the inheritance patterns of many traits? What multiple processes increase genetic variation in biological systems, and how do environmental factors influence the expression of the genotype in an organism?

1st Read About: Mendel and the Gene Idea: Pgs. 262-281Campbell’s Biology 9th edition

Overview: Describe blending and how Mendel’s particulate (gene) theory was different.

Mendel used the scientific approach to identify two laws of inheritance/Mendel’s scientific approach

  • Describe how Mendel was able to control mating by using peas. Explain why peas are an ideal model organism for inheritance studies.
  • Define the following: character, trait, true-breeding, hybridization, P, F1, F2 generations

The law of segregation/Mendel’s model

  • Define allele then sketch a homologous pair of chromosomes, label the allele for both purple and white flower color, and the locus of the flower color gene
  • Mendel developed a model to explain the 3:1 inheritance pattern. List and briefly explain the four concepts. (the fourth is the law of segregation)
  • Define homozygous, heterozygous phenotype, genotype
  • Explain the purpose of a testcross.

The law of independent assortment

  • Explain Mendel’s law of independent assortment

The laws of probability govern Mendelian inheritance

  • State the multiplication rule and addition rules and give a simple example for each.

The inheritance patterns are often more complex than predicted by simple Mendelian genetics

  • List and briefly explain the following: complete dominance, incomplete dominance, codominance
  • List and briefly explain the following genetic disorders (include the pattern of inheritance): Tay-Sachs, cystic fibrosis, sickle cell disease, Huntington’s disease, PKU

2nd Interact: Take notes Mr. Andersen’s “Mendelian Genetics” video

3rdInteract: (Optional)Take notes on Mr. Andersen’s Beginner’s Guide to Punnetts Video

4thSolve Problems: Solve at least one problem of each type on the attached sheet to refresh your memory from Biology I. There are also problems throughout Ch. 14 with selected answers in the back (optional).

5th Interact: Take notes on Mr. Andersen’s Probability in Genetics Video

6th Interact: Take notes on Mr. Andersen’s Advanced Genetics Video

Supplementary Resources: Click the links below for more information to help you learn more about this lesson.

  • Hillis et al.:Independent Assortment of Alleles Animation
  • Hillis et al.: Test Cross
  • DNA From The Beginning: Classical Genetics Tutorials and Animations
  • University of Arizona Biology Project: Mendelian Genetics Monohybrid Problem Set
  • University of Arizona Biology Project: Mendelian Genetics Dihybrid Problem Set
  • University of Arizona Biology Project: Sex-Linked Problem Set
  • Biocoach: Mendelian Genetics

Learn More: For more information about inheritance of traits and production of gametes, follow the links below:

  • The Blue People of Troublesome Creek: interesting story about a family from Kentucky with methemoglobinemia
  • Queen Victoria and Hemophilia: Trace the passage of hemophilia through the royal families of Europe

AP Biology 029 – Mendelian Genetics Video Review Sheet

A. Introduction

1. What did Mendel work with?

2. What is the P Cross?

3. What is the F1 cross?

4. Describe the incorrect idea of “Blending”?

5. The F1 was a “hybrid” – what does that mean?

B. Diagram the first Punnett square that he created below and explain how white flower could come from two purple flowers:

C. Mendel’s Laws:

a. Law of Segregation: like a ______flip. It is a ______of those two alleles. Random ______

b. Independent Assortment: Traits on different chromosomes don’t ______each other. Sometimes things do travel together, but that is because those two genes are found on the same:

D. Pause the video at the Sample Problems and try and work them out.

1. Coin flip:

2. Heterozygous means:

Homozygous means:

3. What is an organism’s genotype? What is an organism’s phenotype?

4. What is the probability of homozygous recessive (rr)?

5. Why is there a greater chance of green seeds in problem 5 than wrinkled seeds (rr) in problem 4 above?

6. Two Punnett squares because you need to multiply the ______together.

E. Disease: Would you want to know?

Review Sheet for AP Biology 029 – Mendelian Genetics Contributed by Winnie Litten —