1. allele a different form of a gene

2. chromosome a microscopic structure in the body that contains DNA and is shaped like a thread Credit: Steffen Dietzel

3. dominant stronger; more powerful; a genetic trait that takes over

4. egg reproductive cells provided by a female, which can join with sperm to form a new offspring

5. gene a unit of heredity, such as a stretch of DNA, that determines traits; a sequence of nucleotides in DNA or RNA that determines traits, such as eye color

6. genotype the genetic makeup of an organism

7. homozygous an organism with two of the same alleles for a trait (TT or tt)

8. heterozygous an organism with two different alleles for a trait (Tt)

9. pedigree a chart that shows the inherited traits over several generations

10. phenotype the physical traits of an organism

11. Punnett Square a chart that shows all the possible combinations of alleles on a grid or cross Credit: Pbroks13

12. recessive weaker; likely to be overridden by something dominant or stronger; a genetic trait that is shown only if the dominant one is not there

13. sperm reproductive cells provided by the male, which can join with an egg to form a new offspring

14. trait a characteristic that can be inherited; a feature of something, like having blue eyes