1. Reproduction and Heredity
Jamika Lasker, B.S., and Erin S. Kelleher, Ph.D.
University of Houston
Dissemination of this activity provided by Baylor College of Medicine.
Drosophila melanogaster (fruit fly) © Thithawat Sanganat.
REPRODUCTION AND HEREDITY
Overview
Students will perform crosses between fruit fly strain with different physical characteristics, and observe 1) the transmission of traits from parents to offspring and 2) that offspring produced by sexual reproduction exhibit diverse combinations of parental traits.
Reference
Lasker, J,, and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Image Reference
Photo © Thithawat Sanganat. Licensed for use.
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.

2. Observable Traits: Male or Female
Identify and record as many differences in physical characteristics between the male and female fruit flies. What are key differences? What might the red arrows be pointing to?
OBSERVABLE TRAITS: MALE OR FEMALE
PROCEDURE
Class Period 1. Discussion and Computer Simulation of Reproduction in Fruit Flies
Project Slide 2 containing photographs of males and female fruit flies (Drosophila melanogaster). The male of the species appears at the bottom of the left photo, and to the right of the female on the composite image on the right. Ask students to identify and record as many differences in physical characteristics and they can. Key differences are body size (females are larger), abdomen shape (females have pointed bottoms, males are more rounded), and abdomen pigmentation (females have stripes all the way down their abdomens, males have solid black bottoms).
Explain to students that the red arrows in both images point to the male fruit fly’s sex comb bristles. Males and females appear different because they have different roles in sexual reproduction. Male fruit flies have elaborate genitalia for passing sperm to the female. Loss of the sex combs reduces the abilities of males to reproduce. Female fruit flies have larger bodies in order to produce large, yolk-filled eggs. The female flies also have a pointed abdomen that allows them to place the fertilized egg onto food, which will provide a nutrition source for the developing offspring.
Tell students that today they will be learning about how sexual reproduction between two different parents can produce diverse offspring.
(continued)
Reference
Lasker, J., and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Images Reference
Photos courtesy of the Jean and Alexander Heard Library, Vanderbilt University Library. BSCI 1511L Statistics Manual: Drosophila phenotypes.
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.

3. Observable Traits: Offspring
The photos above were taken a few years apart. Do the children (offspring) look the same or different from each other?
Which traits were passed from specific parents to specific offspring?
OBSERVABLE TRAITS: OFFSPRING
PROCEDURE (continued)
Project the pictures of a family showing the same family as they appear in different years. (Or you can use a famous family photo). Ask, Do the children (offspring) look the same or different? Prompt students to identify traits that were passed from specific parents to specific offspring. You also may ask students to think about traits they’ve inherited from their parents and/or how they differ from their siblings.
Direct students to perform fruit-fly mating simulator activity as described on their worksheet. The simulator software will allow them to perform matings between flies with different physical characteristics, and observe the diverse offspring produced.
End of Class Period 1.
Reference
Lasker, J., and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Images Reference
Photos ® Frenk Kaufmann. Licensed for use.
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.

4. Physical Trait 1: Eye Color
A fruit fly is born having its eye color determined by parental genes. The most dominant eye color is red (wild-type). The most recessive color is white. What happens when one parent has red eyes and the other has white eyes?
PHYSICAL TRAIT 1: EYE COLOR
PROCEDURE
Class Period 2. Observation of Male and Female Parents, Production of Offspring and Establishment of Experimental Crosses
Tell the students that today they will be using live fruit flies (D. melanogaster) to learn about how physical traits are transmitted from parent to offspring. The students will look at three different physical traits. Project Slide 4 that show images of two different eye colors. Explain to students that different fruit flies can be born having many different eye colors.
Note: The most dominant eye color is red (wild-type), and the most recessive color is white. Other colors that may occur include shades of red, white and brown: garnet, vermillion, white apricot, brown, purple, sepia and even eyes that are half red on top and half white on bottom (called “sunset”).
Normal wild-type flies have red eyes, a light brown body, round wings and straight long bristles.
(continued)
Reference
Lasker, J., and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Images Reference
Macro photos of D. melanogaster eyes courtesy of FlyBase.
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.

5. Physical Trait 2: Wing Shape
How do these flies differ?
PHYSICAL TRAIT 2: WING SHAPE
PROCEDURE (continued)
Now project Slide 5, which shows fruit flies (in each photo, females on the left, males on the right) having different wing shapes. Ask students, How do these flies differ? Explain that we refer to the wing shape as either curly or straight.
(continued)
Reference
Lasker, J., and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Images Reference
Photos ® Frenk Kaufmann. Licensed for use.
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.
Female
Male
Female
Male

6. Physical Trait 3: Bristle Length
PROCEDURE (continued)
Follow with Slide 6, which depicts bristle length on two different fruit flies (long bristles shown in the left image). Repeat the question, How do these flies differ?
(continued)
Reference
Lasker, J., and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Images Reference
Photos ® Frenk Kaufmann. Licensed for use.
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.
Look at the macro images above. How do these fruit flies differ?

7. Genotype Charts
Biologists assign letters to specific characteristics and traits that they observe.
The genetic makeup of traits in the female and male fruit flies you have been provided with are listed in the table below.
GENOTYPE CHARTS
Background
Just like they use letters to refer to DNA nucleotides (A, C, T, G), biologists also assign letters to specific characteristics and traits that they observe. For example, the letter “E” can stand for eye color.
Reference
Lasker, J., and Kelleher, E. (2018). Reproduction and Heredity. University of Houston. BioEd Online:
Key Words
lesson, genetic, life science, science, experiment, gene, chromosome, trait, mutation, heredity, offspring, Drosophila melanogaster, fruit fly, fruit-fly, fruit flies, reproduction, environment, population, middle school, teacher, student,
This activity was funded by NSF Grant to Erin S. Kelleher © University of Houston. Dissemination provided by Baylor College of Medicine via its BioEd Online Website.

8. Science Safety Considerations
Follow all instructions.
Begin investigation only when instructed.
Report accidents.
Do not eat or drink during the experiment.
Wash hands thoroughly after the investigation.
Science Safety Considerations
Students always must think about safety when conducting science investigations. This slide may be used to review safety with your class prior to beginning the activity.
Safety first!
• Always school district and school science laboratory safety guidelines.
• Have a clear understanding of the investigation in advance. Practice any investigation with which you are not familiar before conducting it with the class.
• Make sure appropriate safety equipment, such as safety goggles, is available.
• Continually monitor the area where the investigation is being conducted.
References
Dean R., M. Dean, and L. Motz. (2003). Safety in the Elementary Science Classroom. National Science Teachers Association.
Moreno N., and B. Tharp (2011). The Science of Food Teacher’s Guide. Fourth edition. Baylor College of Medicine.
Key Words
science, classroom, safety, lab, laboratory, rules, safety signs,
© Baylor College of Medicine. 8