Prentice Hall - Science Explorer - Cells and Heredity
Chapter 3- The Science of Heredity
Section 1- Mendel's Work
Questions - Comments - Key Words - Connections
Fertilization Pistil Purebred Gene Alleles Dominant Allele Recessive Allele Hybrid |
Main Ideas; Visuals + Predictions
Mendel's Experiments
Fertilization: The process in which an egg cell and a sperm cell join to form a new organism. Crossing Pea Plants
Pistil: A part in a plant where it produces female sex cells, or eggs.
Stamens: A part in a plant where it produces pollen, which contains the male sex cells, or sperm. Crossing Pea Plants
Purebred: The offspring of many generations that have the same traits. Ex: Purebred short pea plants always come form short parents. F1 Offspring
* Mendel crossed purebred tall plants with purebred short plants. (These are called the parental generation or P generation)
* The offspring are called the Filial or F1. Experiment with other Traits
* In all of Mendel’s crosses, only one form of the trait appeared in the F1 generation. However, in the F2 generation, the “lost” form of the trait always reappeared in about one fourth of the plants.
Dominant and Recessive Alleles
Genes and Alleles Gene: The set of information that controls a trait; a segment of DNA on a chromosome that codes for a specific trait. Alleles: The different forms of a gene. Ex: The gene that controls stem height in peas, has one allele for tall stems and one allele for short stems. Video about Genes and Alleles javascript:openVideo('video/video_sx05_ccv031.mov') * An organism’s traits are controlled by the alleles inherited from the parents. Some alleles are dominant, while other alleles are recessive. Dominant Allele: An allele whose trait always shows up in the organism when the allele is present. (T; TT) Recessive Allele: An allele that is hidden when a dominant allele is present. (It somehow disappears) (t; tt) Alleles in Mendel's CrossesHybrid: An organism that has two different alleles for a trait; an organism that is heterozygous for a particular trait. |