1. Human Traits Lab

2. The characteristics that an organism inherits from its parents are called traits. In humans, traits include the color of a person's hair, skin, and eyes, the blood group, the shape of the nose and lips, and the tendency to be short-sighted or bald. Some of the traits that humans acquire can be modified by the environment, while others cannot.

3. Traits are usually considered to be dominant or recessive
Traits are usually considered to be dominant or recessive. In a dominant trait, only one allele is necessary to see the trait. In a recessive trait, both copies of the allele must be present to see the trait.

4. Procedure Take a look at the human traits listed on your paper.
For each trait, write down which one you express (have).
Write whether it is dominant or
recessive and a possible genotype.

5. dimples or no dimples
dominant
DD or Dd
recessive dd

6. straight or curved thumb
dominant
SS or Ss
recessive ss

7. rolling or non-rolling tongue
dominant
RR or Rr
recessive rr

8. unattached or attached earlobes
dominant
UU or Uu
recessive uu

9. widow’s peak or straight hairline
dominant
WW or Ww
recessive ww

10. bent or straight pinkies
dominant
BB or Bb
recessive bb

11. cleft or no cleft chin
dominant
CC or Cc
recessive cc

12. Procedure
4. Total up how many dominant traits you have 5. Total up how many recessive traits you have

13. Fill in the table on your paper

14. Create a bar graph using the class data

15. Genes determine traits. An allele is a form of a gene
Genes determine traits. An allele is a form of a gene. Each gene has at least two alleles. Each allele may occur in one of two forms, either dominant or recessive. Complete the following to practice understanding how scientists work with alleles. Most traits are the result of several genes, but we will practice with some that are thought to be controlled by a single gene.

16. PART 1: Symbolizing Alleles In the table, several traits are listed
PART 1: Symbolizing Alleles In the table, several traits are listed. The two forms of the gene are listed. Scientists use two forms of the same letter to represent the two alleles. A dominant allele is represented by a capital letter. A recessive allele is represented by a lower case letter. If there is a capital letter, it is usually written first. For each trait, use the letter in parenthesis. The first one has been done for you as an example.

17. PART 1: Symbolizing Alleles

18. PART 2: Determining the Phenotype Genes have at least two alleles
PART 2: Determining the Phenotype Genes have at least two alleles. There are three possible combinations (genotype) of alleles in each pair. If a dominant allele is present, the dominant trait will appear in the organism. In order for a recessive trait to be expressed, both alleles of the gene pair must be recessive. In the table, identify what trait will be seen. The trait that can be seen is called a phenotype. The first example has been done for you.

19. PART 2: Determining the Phenotype

20. PART 3: Determining the Genotype The genotype refers to the alleles in the gene pair. There are three possible combinations. If an organism expresses a dominant trait, there are two possible genotypes. If the organism expresses a recessive trait, there is only one genotype possible. Fill in the table with the possible genotypes for each phenotype. The first one has been done for you.

21. PART 3: Determining the Genotype

22. complete the multiple choice questions and turn it in.