Overview

During this lab you will use a computer simulation to assist you in understanding many of the principles behind the Genetics of Organisms.

You should have received a DrosophiLab Tutorial. Your first task is to work through that tutorial. Use your text or internet to research answers to any questions you may have. If you get stuck, let me know and I will help you out of your dilemma.

Your second task is to use the DrosophiLab simulation to model three representative crosses offlies and answers the questions in the Data and Analysis section of this lab (i.e., mode of inheritance, phenotypes and genotypes of all organisms in the various generations [P, F1, and F2]). You will also apply a statistical test (Х2 test) to your results in order to verify the results.

If you wish to work on this further at home, you may download DrosophiLab at There is also a more detailed manual available on that website.

To get started, click on the DrosophiLab icon on the desktop and work though the tutorial. When you have finished with the tutorial, return here and begin the PROCEDURE portion of thislaboratory exercise.

Objectives

Before doing this laboratory you should understand:

•Drosophila anatomy and basic phenotypic traits;

•Basic patterns (modes) of Mendelian inheritance;

•Monohybrid, dihybrid and sex-linked crosses; and

•2 analysis.

After doing this laboratory you should be able to:

•Determine the phenotypes, genotypesand respective ratiosof each based on ana analysis of the results of genetic crosses of the organisms.

•Determine the modes of inheritance of a trait by analyzing the data resulting from genetic crosses.

•Analyze the results of genetic crosses using the 2 analysis.

PROCEDURE

  1. Using DrosophiLab, perform the following sets of crosses:
  2. Cross one – Monohybrid Cross

1)To generate the F1 generation, cross:

a)Wild type: Wildmale.fly

b)Sepia eye: se se female.fly

2)To generate the F2 generation, from the F1 generation, pick and cross

a)One female fly

b)One male fly

  1. Cross two - Dihybrid Cross (red eyed normal winged X sepia eyed vestigial winged)

1)To generate the F1 generation, cross:

a)Wild type: Wildmale.fly

b)Sepia eye: se vg female.fly

2)To generate the F2 generation, from the F1 generation, pick and cross

a)One female fly

b)One male fly

  1. Cross three - Sex-linked Cross

1)To generate the F1 generation, cross:

a)Wild type male (Wildmale.fly)

b)White eyed female (White eyed female.fly)

2)To generate the F2 generation, from the F1 generation, pick and cross

a)Red-eyed female

b)White-eyed male

  1. For each cross, set number of offspring to 100.
  2. Record the required data in the Data and Analysis Section.
  3. Use the following table of probabilities to evaluate your 2 numbers.

TABLE OF PROBABILITIES
df / 0.95 / 0.90 / 0.70 / 0.50 / 0.30 / 0.20 / 0.10 / 0.05 / 0.01 / 0.001
1 / 0.004 / 0.016 / 0.15 / 0.46 / 1.07 / 1.64 / 2.71 / 3.84 / 6.64 / 10.83
2 / 0.10 / 0.21 / 0.71 / 1.39 / 2.41 / 3.22 / 4.61 / 5.99 / 9.21 / 13.82
3 / 0.35 / 0.58 / 1.42 / 2.37 / 3.67 / 4.64 / 6.25 / 7.82 / 11.35 / 16.27

1

Bio IIH – DrosophiLab

DATA AND ANALYSIS

Monohybrid Cross

  1. List the phenotypes and genotypes of the parental (P1) generation:

PhenotypesGenotypes

Male Parent______

Female Parent______

  1. Prepare a Punnett Square for the parental (P1)cross.

P1 Cross

  1. List the phenotypes, the number of each phenotype counted, and genotypes for the F1 generation.

Phenotypes# CountedGenotypes

______

______

  1. Prepare a Punnett Square for the first filial (F1), cross.

F1 Cross

  1. List the phenotypes, the number of each phenotype counted, and genotypes for the F2 generation

Phenotypes# CountedGenotypes

______

______

  1. What is the mode of inheritance for these crosses? ______
  2. How did you know (identify) this mode of inheritance? ______

______

  1. What was the 2 value for your F1 cross? ______
  2. Based on this 2 value, was your mode of inheritance determination:

supported ______not supported?______

Dihybrid Cross

  1. List the phenotypes and genotypes of the parental (P1) generation:

PhenotypesGenotypes

Male Parent______

Female Parent______

  1. Prepare a Punnett Square for the P1 cross.

P1 Cross

  1. List the phenotypes, the number of each phenotype counted, and the genotypes for the F1 generation:

Phenotypes# CountedGenotypes

______

  1. Prepare Punnett Squares for the first filial (F1), cross.

F1 Cross

  1. List the phenotypes, the number of each phenotype counted, and genotypes for the F2 generation:

Phenotypes# CountedGenotypes

______

______

______

______

  1. What is the mode of inheritance for these crosses? ______
  2. How did you know (identify) this mode of inheritance? ______

______

  1. What was the 2 value for your F1 cross? ______
  2. Based on this 2 value, was your mode of inheritance determination:

supported ______not supported?______

Sex-linked Cross

  1. List the phenotypes and genotypes of the parental (P1) generation:

PhenotypesGenotypes

Male Parent______

Female Parent______

  1. Prepare a Punnett Square for the parental (P1) cross.

P1 Cross

  1. List the phenotypes, the number of each phenotype counted, and the genotypes for the F1 generation:

Phenotypes# CountedGenotypes

______

______

______

______

  1. Prepare a Punnett Square for the first filial (F1), cross.

F1 Cross

  1. List the phenotypes, the number of each phenotype counted, and genotypes for the F2 generation:

Phenotypes# CountedGenotypes

______

______

______

______

  1. What is the mode of inheritance for these crosses? ______
  2. How did you know (identify) this mode of inheritance? ______

______

  1. What was the 2 value for your F1 cross? ______
  2. Based on this 2 value, was your mode of inheritance determination:

supported ______not supported?______

1

Bio IIH – DrosophiLab