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chizani03 chizani03
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11 years ago
Below is a list of genetic traits that are determined by a single gene.  You will determine your phenotype and possible genotype for the indicated traits.  If the trait is a recessive trait, use two lower case letters to indicate that the inheritance is of two like alleles (homozygous recessive).   
If the trait is the result of a dominant gene, the genotype may be homozygous dominant (indicated by two identical upper case letters) or it may be heterozygous (indicated by one upper case and one lower case letter).  If you have a dominant trait and can analyze family members to be certain of the genotype, the known genotype should be posted with an explanation on how the genotypic determination was made.  If the genotype cannot be determined with 100% certainty, both genotype possibilities should be listed.  Record your results on the data sheet.
Inherited Traits
1.  Widow's peak - The W for widow's peak is dominant over a straight hairline (w allele).  A widow's peak is a distinct downward point in the frontal hairline.
2.  Albinism - The A allele is dominant and leads to melanin production, thus pigmented skin.  Individuals with albinism have the aa genotype.
3.  Attached earlobes - The E allele for a free earlobe is dominant over the e allele for attached earlobes.
4.  Eye color - The P allele produces pigment in the iris of the eye producing either brown, green, hazel or black eye color.  Individuals that are homozygous recessive (pp) do not produce any pigment and as a result have either blue or gray eyes.
** Note that eye color is also influenced by more than one gene locus.  This eye color gene refers to the pigment of the iris.
5.  Mid-digit hair - Hair on the middle segment on the fingers (between two joint knuckles) is a dominant trait (M).  Absence of hair in this location is due to a recessive gene in the homozygous condition (p).
6.  Interlocking Fingers.  Fold the hands together without thinking about it.  If the left thumb is crossed over the right, the designation is C.  If the right thumb is crossed over the left, the person is homozygous recessive for this trait (cc).  Don't think about it too much when performing this action.
7.  Bent finger - Lay the fingers flat on top of a desk and relax.  If the little finger bends towards the index finger, the genotype is dominant for this trait (B).
8.  Hitchhikers thumb - Bend the thumb backward.  If the thumb bends back at the last joint at an angle greater than 60 degrees, then this indicates the recessive trait (hh).
9.  Dimpled chin - Squeeze the chin (you need to do this one with a partner or a mirror).  If there is a dimple, this indicates the dominant (D) allele.
10.  Relative finger length.  A sex-influenced trait (not sex-linked) relates to the relative lengths of the index and ring fingers.  The allele for a short index finger, S', is dominant in males. The allele for long index finger is S. In females both copies of the S' allele must be present in order for the index fingers to be shorter than the ring fingers. (It is considered recessive in females.)  In rare cases, each hand is different.
11.  Tongue Rolling.  The ability to roll one's tongue (the sides of the tongue curl up towards the center producing a U-shaped tongue) is due to a dominant allele, T.  The homozygous recessive condition, tt, results in the inability to roll the tongue.
12.  Freckles.  The tendency to develop freckles (melanin spots) is a dominant trait (F) over the absence of freckles (ff). 
13.  Aromatic urine - The urine of some people has a very distinctive odor after eating asparagus (use A and a for alleles). This appears to be a recessive trait.  Eat some asparagus.  If the urine is "aromatic" afterwards, it will be obvious and indicates the recessive trait. Most of you will be able to answer this already without having to repeat this experiment.
14.  Color vision.  The ability to distinguish between red and green colors is due, in part, to proteins called opsins.  The two genes for red opsin and green opsin are on the X chromosome. Often a person lacks both normally functioning opsin genes and has red/green color blindness.   The inheritance pattern is X-linked recessive.  The normal allele is XC. The abnormal recessive allele is Xc. In order for a woman to be color blind, both X chromosomes would lack the normal allele.  For a man to be color blind, the X chromosome would lack the normal allele.  The Y chromosome does not contain this gene locus. 
15.  Sex determination.  In humans, the sex of an individual is determined by a pair of chromosomes designated X and Y.  Males have one X and one Y chromosome.  Females have two X chromosomes.
16.  Long Palmar Muscle (Incomplete Dominance).  Clench the left hand tightly and feel the wrist with the right hand; do the same for the right hand. Three tendons in a wrist indicate a long palmar muscle. If there are long palmar muscles in both wrists, the genotype is P1P1. If both wrists do not contain long palmar muscles, the genotype is P2P2. If there is a long palmar muscle in only one arm, the genotype is heterozygous, P1P2 for this trait. This trait would be an example of incomplete dominance.
17.  Hair texture.  Another example of incomplete dominance is hair texture.  The texture of untreated hair is determined by protein content.  If the hair is naturally curly, the genotype is C1C1  If it is wavy, the genotype is heterozygous C1C2; straight hair indicates a homozygous recessive, C2C2, genotype.
18.  Hair Whorl direction.  Hair at the back of the head should be observed.  The dominant condition is when the hair is going in a clockwise direction.  The recessive condition is when it is going in a counter clockwise direction.  Use W for the dominant and w for the recessive conditions.
ONE NOTE:  Remember the difference between phenotype and genotype. Phenotypes are descriptive words, not abbreviations like XY or Ss. For example, for sex: the phenotype would be 'male' or 'female' and the genotype would be 'XY' or 'XX', respectively. Please do not write genotypes in your phenotype column! This is a common, but easily avoidable, error.

Inherited Traits   Phenotype     Genotype
1.  Widow's Peak      
2.  Albinism      
3.  Attached earlobes      
4.  Eye color      
5.  Mid-digit hair      
6.  Interlocking Fingers      
7.  Bent Finger      
8.  Hitchhikers thumb      
9.  Dimpled chin      
10.  Relative finger length      
11.  Tongue Rolling      
12.  Freckles      
13.  Aromatic Urine      
14.  Color Vision      
15.  Sex Determination       
16.  Long Palmar Muscle       
17.  Hair Texture       
18.  Hair Whorl      
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wrote...
11 years ago
I'm assuming you can find the phenotype for albinism but the genotype is aa
chizani03 Author
wrote...
11 years ago
anybody please help, i do not even have a clue how to do this. All i need is direction and i will do the homework. Thank you
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