Question

Human Mendelian Traits Mendelian Traits are those traits which follow Mendel's rules of only 2 possible versions of a gene(1 dominant, 1 recessive). There are only a few examples of this in humans. 1. Circle the heterozygous dominant genotypes: AA Aa aa YyYY W Re RR 2. Circle the homozygous recessive genotypes: AA Aa aa YyYY V ir Rr RR 3. Use the chart below to determine your phenotype (observable characteristic) and possible genotype(s) (a pair or pairs of alleles). Since you cannot do a genetic test right now, if you have the dominant phenotype, you should include both the homozygous and heterozygous genotypes-see the example for Advanced Sleep Phase Syndrome in the first row. Possible Alleles Wakes up very early (E) Wakes up at normal time (e) Your Phenotype ex. Wakes up very early Your Genotype EE (homozygous) or Ee (heterozygous) Trait Advanced Sleep Phase Syndrome Achoo Syndrome Ear Wax (wet/dry) Sneezes in the sun (A) Doesn't sneeze in the sun (a) Wet (W) Dry (w) 4. Did you have mostly dominant or recessive traits? 5. Compare your findings with all other students. a. For which trait were most students dominant? b. For which trait were most students recessive?

Answer 1

In Mendelian traits, dominant allele is written by capital letter & recessive allele is written by small letter. Thus, homozygous dominant genotype will have two same capital letters, homozygous recessive genotype will have two same small letters & heterozygous genotype will have one capital & one small letter (Same letter).

1) Heterozygous dominant genotypes will be Aa, Yy & Rr.

2) Homozygous recessive genotypes will be aa, yy & rr.

3) Note: This question asked about your particular phenotype.

If you have Achoo syndrome (Sneezes in the sun), your genotype can be either AA (Homozygous) or Aa (Heterozygous). If you don't have Achoo syndrome (Doesn't sneezes in the sun), your genotype will be aa (Homozygous recessive).

If your ear wax is wet, your genotype can be either WW (Homozygous) or Ww (Heterozygous). If your ear wax is dry, your genotype will be ww (Homozygous recessive).