* Survey a number of personal genetic characteristics to determine phenotype and possible genotypes.
* Analyze the type of inheritance shown in several extended families by examining various pedigree charts.
1. Dimpled chin. A cleft in the chin is a dominant trait. (D, allele for dimpling; d, allele for absence of a dimple)
2. Free ear lobe. In most people, the ear lobe hangs free (dominate allele, E). But, if you are homozygous recessive (ee), your ear lobe is attached directly to your head.
3. Widow's peak. The expression of the dominant gene (W) results in a hairline that comes to a distinct point. This point is known as a widow's peak that is visible in the center of the forehead. The recessive allele (w) produces a continuous hairline if homozygous.
4. PTC tasting. Some people detect a distinct bitter taste in small concentrations of the chemical phenylthiocarbamide (PTC). The dominant gene (T) determines a taster. If you cannot taste PTC, then you must be homozygous recessive (tt). Place a strip of PTC paper from the lab kit on your tongue and allow it to remain there for about 10 seconds. If you are a taster, you will know it. If you have any doubt whether you taste the chemical or not, you are a non-taster.
5. Interlocking fingers. When the fingers are interlocked, some people will almost invariably place the left thumb on top of the right (dominant gene F). Others will place the right over the left (recessive allele f).
6. Bent little finger. A dominant gene B causes the last joint of the little finger to bend inward toward the fourth finger. The recessive gene (b) is for that finger to be straight. Lay both hands flat on the table, relax your muscles, and see whether you have a bent or a straight little finger.
7. Hitchhiker's thumb. This characteristic is properly known as distal hyperextensibility of the thumb. It can be determined by bending the distal joint of the thumb back as far as possible. Some people can bend that part of the thumb back until it is almost at a 90-degree angel between the two joints. Having "hitchhiker's thumb" is due to the recessive gene h (dominant allele, H).
8. Long palmar muscle. Clench your fist tightly and flex your hand toward you. Now feel the tendons of your wrist. If there are three, you have the long palmar muscle. If there are only two tendons (the large middle one is missing), you do not have this muscle. Look at both wrists. If you have the muscle in one or both, you are homozygous recessive (ll). If not, you have the dominant allele (L).
9. Mid-digital hair. Some people have hair on the middle joint of one or more of their fingers. A complete absence of mid-digital hair is due to the recessive gene (m). If the dominant allele (M) is present, there will be hair on the back of one or more middle digits.
10. Tongue rolling. The ability to roll one's tongue is due to a dominant allele (K). The homozygous recessive condition, kk, results in the inability to roll the tongue. If you are a "tongue-roller," you will be able to stick out your tongue and curl up the sides. Can you stick out your tongue and roll up the tip?
11. Blood type. Do you know your blood type? Don't report whether you are Rh+ or Rh-, just the blood type. If you know, or can find out, the blood types of your biological parents or your kids, it would be interesting to diagram a blood type pedigree for your family.
* Analyze the type of inheritance shown in several extended families by examining various pedigree charts.
1. Dimpled chin. A cleft in the chin is a dominant trait. (D, allele for dimpling; d, allele for absence of a dimple)
2. Free ear lobe. In most people, the ear lobe hangs free (dominate allele, E). But, if you are homozygous recessive (ee), your ear lobe is attached directly to your head.
3. Widow's peak. The expression of the dominant gene (W) results in a hairline that comes to a distinct point. This point is known as a widow's peak that is visible in the center of the forehead. The recessive allele (w) produces a continuous hairline if homozygous.
4. PTC tasting. Some people detect a distinct bitter taste in small concentrations of the chemical phenylthiocarbamide (PTC). The dominant gene (T) determines a taster. If you cannot taste PTC, then you must be homozygous recessive (tt). Place a strip of PTC paper from the lab kit on your tongue and allow it to remain there for about 10 seconds. If you are a taster, you will know it. If you have any doubt whether you taste the chemical or not, you are a non-taster.
5. Interlocking fingers. When the fingers are interlocked, some people will almost invariably place the left thumb on top of the right (dominant gene F). Others will place the right over the left (recessive allele f).
6. Bent little finger. A dominant gene B causes the last joint of the little finger to bend inward toward the fourth finger. The recessive gene (b) is for that finger to be straight. Lay both hands flat on the table, relax your muscles, and see whether you have a bent or a straight little finger.
7. Hitchhiker's thumb. This characteristic is properly known as distal hyperextensibility of the thumb. It can be determined by bending the distal joint of the thumb back as far as possible. Some people can bend that part of the thumb back until it is almost at a 90-degree angel between the two joints. Having "hitchhiker's thumb" is due to the recessive gene h (dominant allele, H).
8. Long palmar muscle. Clench your fist tightly and flex your hand toward you. Now feel the tendons of your wrist. If there are three, you have the long palmar muscle. If there are only two tendons (the large middle one is missing), you do not have this muscle. Look at both wrists. If you have the muscle in one or both, you are homozygous recessive (ll). If not, you have the dominant allele (L).
9. Mid-digital hair. Some people have hair on the middle joint of one or more of their fingers. A complete absence of mid-digital hair is due to the recessive gene (m). If the dominant allele (M) is present, there will be hair on the back of one or more middle digits.
10. Tongue rolling. The ability to roll one's tongue is due to a dominant allele (K). The homozygous recessive condition, kk, results in the inability to roll the tongue. If you are a "tongue-roller," you will be able to stick out your tongue and curl up the sides. Can you stick out your tongue and roll up the tip?
11. Blood type. Do you know your blood type? Don't report whether you are Rh+ or Rh-, just the blood type. If you know, or can find out, the blood types of your biological parents or your kids, it would be interesting to diagram a blood type pedigree for your family.