Study Guide: Genetics (Chapter 4)
VOCABULARY
Know the 4-1 and 4-2 Vocab definitions
KNOW
Foundation of Genetics
 A gene is a section of DNA that has information about a specific trait of an organism.
 Heredity is the passing of traits to offspring.
 Genetics is the study of how traits of organisms are passed from parents to offspring.
 An allele is each form of a gene with different information.
 A genotype consists of alleles that make up an organism (Example: Tt).
 A phenotype consists of observable traits and all characteristics of an organism (Example: tall).
 The law of independent assortment states that factors for one trait separate independently of how factors for other traits
separate.
 Heterozygous genotypes have two alleles for a gene having different information - one capital letter (dominant), one
lowercase letter (recessive) (Example: Tt).
 Homozygous genotypes have two alleles for a gene having the same information - both capital letters (dominant), or
both lowercase letters (recessive) (TT or tt).
 Dominant means a genetic factor that blocks another genetic factor.
 Recessive means a genetic factor that is hidden by the presence of a dominant factor.
 DNA found is found in all cells.
 Gregor Mendel studied pea plants.
 A parent will pass 1 out of 2 alleles for a trait to its offspring.
 If you get different alleles for a trait from each parent, you are called a hybrid (or heterozygous).
 Examples of each of the following genotypes:
o homozygous recessive = tt
o homozygous dominant = TT
o heterozygous = Tt
Understanding Inheritance
1. A pedigree is a model that shows genetic traits that were inherited by members of a family tree.
2. Incomplete dominance involves alleles that produce a phenotype that is a blended form of the parents’ phenotypes.
3. Multiple alleles involves a situation when more than two alleles are found on a gene.
4. Polygenic inheritance is a situation when multiple genes determine the phenotype of a trait.
5. A Punnett square is a model used to predict possible genotypes and phenotypes of offspring.
6. In Punnett squares, a capital letter stands for a dominant allele, and lowercase stands for a recessive allele.
7. Blood type in humans is controlled by 3 different alleles. The 4 possible phenotypes are: A, B, O, AB
8. A red and white flower are crossed. The genes for color exhibit incomplete dominance. What will their offspring be?
100% pink
9. Two red flowers are crossed. One is homozygous and one is heterozygous for color. If red is the dominant allele, and
white is recessive, what will be the ratio of colors in the offspring? 100% red
ALSO STUDY...
 Opening assignments from this chapter
 4-1 and 4-2 notes
 The 4-1 and 4-2 quizzes
 “Genetics Practice Problems” worksheet
 “Punnett Square Practice” worksheet
 “Bikini Bottom Genetics” worksheet
 from the Glencoe website (link is on my website): standards review quiz, standards assessment quiz, eFlashcards
 from the textbook: The end-of-chapter review questions.