Genetics is the study of the mechanisms of heredity. Stated another way, it is the study of the ways traits or characteristics are passed on from generation to generation. People differ from each other in the expression of these traits; thus, expressing their own individuality and uniqueness.
In this exercise, you will examine in more detail a characteristic that is known to be controlled by one set of human genes.
1. You, the student, will trace one trait through three generations of your family with you, the student, in the one of the generation.
(Lab 20 presentation will help you make your family pedigree.)
( You may choose maternal or paternal side of your family depending on which one will best meet the criteria for this project.)
2. The trait you are tracing has to appear at least in two of the three generations of your pedigree.
3. You will use different colors to represent the dominant and recessive traits.
4. Your pedigree chart will have a title and a key in it.
5. Your generations will be numbered in Roman numbers aligned vertically on either the right or left side.
6. You will have first names on each circle or square. (No last names, please.)
7. Under your circles or squares you will figure out and write the genotypes of each.
8. You will need to see an example of the finished project from the teacher to put all the information together. You may purchase tagboard or the teacher will supply you with tagboard if you are not able to purchase it.
9. If you are adopted or have special circumstances in your family. Please talk to me individually to work out a comparable project.
10. Neatness will count. Using the computer to enhance the neatness of your project will be rewarded over handwritten information. I will reduce your final grade by 10% if handwritten. (You have access to computers every SRB).
Project is due December 14th.
I will be happy to answer any and all questions.
**Need to choose a characteristic for your pedigree research?Here are a few to choose from.
Attempt to roll your tongue into a U-shape, in which the sides of your tongue are curled upwards. Tongue rollers carry a dominant gene, R.
A dominant gene W causes the hairline to form a distinct downward point in the center of the forehead. Baldness will mask the expression of this gene.
The inheritance of a dominant gene E results in the free or unattached earlobe. If the lobe is attached directly to the head, the recessive, or ee genotype has been inherited.
Some individuals can bend the last joint of the thumb backwards at about a 45 degree angle. These individuals are homozygous for a recessive gene (ht), but there is considerable variation in the expression of the gene. For our purposes we shall consider those who cannot bend at least one thumb backwards about 45 degrees, are carrying the dominant gene (HT).
Bent Little Finger
The dominant gene F causes the terminal bone of the little finger to angle toward the fourth (ring) finger. Individuals whose little fingers are straight possess the homozygous recessive condition, ff. Check for this characteristic by laying your hands flat on the table and relaxing them.
The presence of hair on the middle segment of the fingers is caused by a dominant gene, M. The homozygous recessive condition, mm, results in the lack or absence of hair on the middle segments.
The inheritance of cheek dimples is controlled by a dominant gene D. The dd genotype or condition lacks the ability to express facial dimples.
The length of the big toe (hallux) is governed by the gene H. Individuals whose hallux is shorter in comparison to the second toe possess the dominant gene H. The inheritance of the homozygous recessive genotype (hh), results in the big toe being longer than or equal to the second toe.