Complex Patterns of Heredity: Mrs. Neistadt Biology
Review: History of Genetics• *1866- Gregor Mendel began the study of genetics testing the inheritance of traits in the pea plant.• * He tested seven different traits: 1. Pea seed color 2. Flower color 3. Seed pod color 4. Seed shape or texture (wrinkled or smooth) 5. Seed pod shape 6. Stem length 7. Flower position
Vocabulary Review:1. A gene or trait that always shows itself is called _________________. Dominant Trait2. A gene or trait that will be hidden when adominant trait is present is called ___________. Recessive Trait3. A chart that shows possible gene combinationsof offspring is called Punnett Square_________________________.4. Organisms that have two like genes for a Homozygousgiven trait are called _____________.
Vocabulary Review:5. Organisms that have two unlike genes for agiven trait are called ___________. Heterozygous6. Another term for an organism that hastwo like genes for a certain trait is_________. Purebred7. Another term for an organism that hastwo unlike genes for a certain trait is Hybrid_______.
Complex Patterns of Heredity:• Some genes to not follow Mendel’s patterns, some are more complex.• *Incomplete Dominance- When one gene for a certain trait is not completely dominant over another a blending occurs. This is called incomplete dominance.
Complex Patterns of Heredity:• Sometimes two dominant genes are present for one trait.• *Co-dominance: A pattern of heredity that occurs when two genes are present for one trait. Neither gene is dominant or recessive over the other. They do not blend; they both show up in the organism.
Co-dominance:• Co-dominance: when two dominant genes are present for a single trait
Complex Patterns of Heredity:• * Multiple Alleles: Many traits are controlled by more than two possible variations. These traits are controlled by multiple alleles. – Example: Human blood groups
Complex Patterns of Heredity:• *Polygenic Trait: Some traits are controlled by many genes interacting with one another. These traits are called Polygenic Traits. – Examples: height, skin color, eye color
Polygenic Trait• Many traits working together: