Introduction: (Initial Observation)
Genetic studies can be performed to identify the effect of gene on properties and characteristic of any organism. (Gene is a hereditary unit that occupies a specific location on a chromosome and determines a particular characteristic in an organism.) We may perform genetic studies on human, animals, plants and even bacteria. Every genetic study will focus on a different characteristic of the subject. Connection between hair and eye color is among genetic studies that can be performed on humans and can be conducted by Intermediate or senior students. The general purpose of doing these experiments is to understand the effect of gene on certain characteristics of humans and compare it with other environmental factors that may have a similar effect.
Authors note: The first time that I learned about world countries and the fact that African people are black and people from the north pole are white, I wondered if it can be the effect of weather and temperature. I though Africans are black because of sun-burn and people from north pole are white because of the fat layer under their skin caused by a cold weather. Later when I learned that African people will remain black even if they move to a colder area, again I thought maybe millions of years exposure to the hot sun at African deserts has had a long lasting effect on their skin and if they live in a cold area for the same amount of time, they may change color and become white again. Today genetic studies can help us to understand the effect of gene on skin color and on many other characteristics of human.
By looking around we notice that people have different eye colors and different hair colors. Such characteristics can be genetic or just an accident. For the purpose of this project we want to discover if such characteristic is genetic. (inherited from parents or other ancestors).
Find out about genes and genetics. Read books, magazines or ask professionals who might know in order to learn about the effect or genes in a persons characteristics. Keep track of where you got your information from.
Following are some helpful links for you to start.
Genetics is about the transfer of information among many different levels. The foundation level is the molecule called DNA. The information in DNA is organized into Genes. Genes, in turn, make up Chromosomes, which when taken all together form an organism’s Genome. Every cell in an Individual contains the genome. The final level shows how individuals are genetically connected to their families and larger populations through inheritance patterns.
Think of chromosome as a long string of DNA, wrapped around some protein. All the human DNA is organized into two sets of 23 chromosomes. Sections of DNA are called genes. Each gene carries information for the production of a unique protein that will perform a specialized function in the cell. Human has about 40,000 genes.
Finding any relation between hair color and eye color is one step toward identifying the genes that are responsible for such colors.
Following are links to some related information.
Information that you gather, will give you some idea, but finally you have to do the job and do your own research.
Is there any genetic relation between hair color and eye color? Here we emphasize on the world genetic because our research project will not cover other effects such as aging, weather and cosmetics. For example we want to know if most people with black hair, do they also have black eyes? and also we want to know if these have any relation with the eye color and hair color of their parents and ancestors.
We consider eye color as an independent variable, and hair color as a dependent variable.
Since we want to know the effects of genetics on eye color and hair color, we can also define the eye color and hair color of parents as independent variable and the eye color and hair color of child as dependent variables.
Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis.
Hair color and eye color can have a genetic root and that is why often we can identify the race of people by a quick look (Unless they have a mixed genetic background). Also there is no genetic relation between eye color and hair color.
Please notice that the title of this project is only about relation between eye color and hair color. So you do not have to find any relation between the eye color of people with the eye color of their parents. However we are expanding our question and experiment with the idea of getting more useful results.
We design a questionnaire for the information that is subject of our study and distribute it among classmates and family friends. Then we compile the results in tables and analyze it to reach to a conclusion. This is a sample questionnaire (Modify it as you like):
1. Ethnic Background
2. What is your ancestry? (list primary ancestry first)
3.Are you a male or female?
4. Your Eye Color
5. Your hair Color Before age of 25 (To exclude changes caused by aging)
6. Your Mother’s Eye Color
7. Your Mother’s hair Color Before age of 25 (To exclude changes caused by aging)
8. Your Father’s Eye Color
9. Your Father’s hair Color Before age of 25 (To exclude changes caused by aging)
Example : the numbers are the count of observations.
|Brown Hair||Blonde Hair||Black Hair||Red Hair|
Your main data table may look like the above table, with different values. This table will show the number of classmates with certain eye color and certain hair color. If you add each column, you will know the total number of classmates with certain hair color. If you add a row, you will know the total number of classmates with certain eye color.
Additional steps are:
Make a similar table to show how many of people with each eye color and hair color, have at least one parent with the same hair color and eye color.
Make a similar table to show how many of people with each eye color and hair color, have at least one parent with the same eye color.
Make a similar table to show how many of people with each eye color and hair color, have at least one parent with the same hair color.
Values in each of the above four tables will be shown with a different color bar in a 3D bar graph.
Instead of drawing bar graphs, you may also make them using Styrofoam or wooden sticks.
Materials and Equipment:
You need some questionnaires and some papers. You may want to use a personal computer and a spread-sheet program such as excel to simplify your calculations.
Results of Experiment (Observation):
Enter the results of your collected data into tables that are easy to understand and analyze. If you find that a large percentage of each hair color is matching with a large percentage of a specific eye color, you may use that to conclude that a specific gene may be in charge of defining eye color and hair color.
Sample hair-color eye-color data
The following table shows data on the relation between hair color and eye color among 592 subjects. The question is how to understand the nature of the association between hair and eye color.
For any two-way table, the expected frequencies under independence can be represented by rectangles whose widths are proportional to the total frequency in each column, and whose heights are proportional to the total frequency in each row ; the area of each rectangle is then proportional to expected frequencies. This is called a Sieve Diagram.
Another Sample data:
|Eye and Hair Color of European Children|
In the following table, you will also see a column titled EXPECTED. The numbers in this column are calculated. For example to calculate the expected frequency for green eye and red hair, you will multiply the total number of green eyes (=199) by the total number of red hairs (=113) and divide the result by the total number of samples (=762).
Deviation from the expected frequency can be used to determine any possible relations.
In the above table, you will need to calculate the column titled EXPECTED. For example to calculate the expected frequency for green eye and red hair, you will multiply the total number of green eyes (=199) by the total number of red hairs (=113) and divide the result by the total number of samples (=762).
Summary of Results:
Summarize your results in tables and diagrams as described above.
Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.
Related Questions & Answers:
What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.
If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.
If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.