the study of how traits are passed from parents to offspring
DESCRIPTION
Let’s give one example… He crossed purple and white- flowered pea plants (P 1 generation) What do you suppose the offspring were like?TRANSCRIPT
http://www.whitehouse.gov/omb/budget/fy2005/images/hud-2.jpg
The study of how traits are passed from parents to offspring.
http://history.nih.gov/exhibits/nirenberg/images/photos/01_mendel_pu.jpg
•Before anyone knew anything about DNA, Gregor Mendel began to study patterns of inheritance in plants.•His discoveries became the foundation for the field of genetics.•So what did he do? 1822-1884
http://fig.cox.miami.edu/~cmallery/150/mendel/c14x1sweetpeas.jpg
Let’s give one example…He crossed purple and white-flowered pea plants (P1 generation)
What do you suppose the offspring were like?
http://fig.cox.miami.edu/~cmallery/150/mendel/cross.htm
100% purple flowers
(F1)Then, he crossed
these purple offspring
What do you suppose the second generation of offspring (F2) were like?
75% purple 25% white
WHY?
To understand the results, we should review some vocabulary…
Gene: a part of a chromosome (DNA) that codes for one trait or protein.
http://www.gsi.de/forschung/bio/fig3.JPG
•Humans have 20-25,000 genes and 46 chromosomes•For each trait, we receive one gene from Mom and one from Dad
Genotype: a description of the genes using letters.
Dominant: a gene that always shows up in the phenotype. (capital letter)Recessive: a gene that is hidden by a dominant gene; shows up only when the dominant gene is not available. (lower case letter)
http://discover.edventures.com/images/termlib/g/genotype/support.gif
What are the genotypes and phenotypes for these flowers?
Phenotype: a physical description of the observed traits
Homozygous: two of the same letters in the genotype.
Heterozygous: two different letters in the genotype.