Concept 11 Genes get shuffled when chromosomes exchange pieces.
As Morgan and his coworkers identified more and more inherited traits in fruit flies, they noticed that flies often showed particular combinations of traits. This suggested that certain genes were "linked," and inherited together as a unit. They identified four such units or "linkage groups" — equal to the number of paired chromosomes observed under the microscope. This provided further evidence that genes are located on chromosomes.
Morgan's group used the phenomenon of linkage to construct maps of the fruit fly chromosomes. They found that linked genes are sometimes separated during meiosis, when the homologous chromosomes exchange pieces. How often a pair of genes are separated provides a measure of the relative distance between them on a chromosome. Distant genes recombine frequently. Nearby genes rarely recombine and are closely linked.
Children resemble their parents.
Genes come in pairs.
Genes don't blend.
Some genes are dominant.
Genetic inheritance follows rules.
Genes are real things.
All cells arise from pre-existing cells.
Sex cells have one set of chromosomes; body cells have two.
Specialized chromosomes determine sex.
Chromosomes carry genes.
Genes get shuffled when chromosomes exchange pieces.
Evolution begins with the inheritance of gene variations.
Mendelian laws apply to human beings.
Mendelian genetics cannot fully explain human health and behavior.