8.3 & 8.4 AP Biology Lecture

Genes are carried on Chromosomes

LOCUS

Genetic Linkage

• Association between genes on the same chromosome

• Do not show random assortment• The closer the genes are, the LOWER the

frequency of recombination (crossing over)• Studied by Morgan in Drosophila fruit flies

Sex Linkage

• Inheritance of a gene that is carried on the X chromosome

• Hemophilia, color blindness, baldness etc.

Plasmid

Plasmids are small circular pieces of DNA that have genes for:•Unusual metabolic activities (to clean up oil spills)•Antibiotic resistance (major threat to human health)

Plasmids can be transferred from one bacteria cell to another