Genetics Lab Review

1. Genetics is the study of genes, heredity, and how traits pass from parents to offspring.

2. This lab likely used a virtual simulation instead of a real pea plant.

3. Gregor Mendel’s three discoveries about genetics:

• Law of Segregation: During gamete formation (sperm and egg cells), alleles for a trait separate from each other.
• Law of Independent Assortment: Genes for different traits are inherited independently during gamete formation.
• Law of Dominance: In some cases, one allele (dominant) can mask the expression of another allele (recessive) for the same trait in an organism.

4. DNA (deoxyribonucleic acid) contains the genetic instructions for building and maintaining an organism. It’s like the blueprint of life.

5. A molecule of DNA is called a double helix because of its twisted, ladder-like structure.

6. The DNA of many organisms, including plants, contain two sets of chromosomes. One set comes from each parent.

7. A chromosome pair consists of two similar chromosomes, each carrying genes for the same traits but potentially different versions (alleles) of those genes.

8. The portion of a chromosome containing the code for a particular physical trait is a(n) gene.

9. Each matching gene with a chromosome pair is a(n) allele. There can be different versions (alleles) of a gene for the same trait.

10. The physical trait examined in this virtual lab was likely stem color (purple or green).

11. Biological inheritance is the passing of genes from parents to offspring. These genes determine the traits of the offspring.

12. Genotype refers to the specific combination of alleles an organism has for a particular trait. It’s the genetic makeup. (e.g., PP, Pp, pp)

13. Phenotype refers to the observable physical characteristics of an organism, determined by the interaction of genotype and environment. (e.g., purple stem, green stem)

14. Brassica rapa expresses the trait for the purple stem when it has two dominant alleles (PP) or one dominant allele and one recessive allele (Pp) for stem color.

15. Brassica rapa expresses the trait for the green stem only when it has two recessive alleles (pp) for stem color.

16. A dominant allele is an allele that masks the expression of a recessive allele for the same trait when present together.

17. A recessive allele is an allele that can be masked by a dominant allele and only shows its effect on the phenotype when paired with another recessive allele.

18. The principle of dominance states that when an organism has two different alleles for a trait, the dominant allele will be expressed, and the recessive allele will be masked.

19. A recessive trait can be expressed in an organism only if the organism has two recessive alleles for that trait (one from each parent).

20. The male part of the flower is the stamen. At the top of it is an anther, which contains the pollen grains (containing sperm cells).

21. The female part of the flower is the pistil. At the top of it is a sticky pad called the stigma, which receives pollen.

22. A Punnett square is a grid used to predict the possible genotypes of offspring based on the parents’ genotypes.

23. An uppercase letter is assigned to the dominant allele and a lowercase letter is assigned to the recessive allele for a particular trait.

24. A progeny is a group of offspring resulting from a controlled genetics experiment.

25. Each first generation plant should have a purple stem because they would inherit one dominant allele (P) from each parent in the cross.