3. Chromosomal Theory of Inheritance- Genes are located on c’somes and the behavior of c’somes during meiosis & fertilization accounts for inheritance patterns.

5. There are more genes in a cell the chromosomes Each chromosome has thousands of genes on it Linked Genes- genes that are located close together on a the same chromosome. Are more likely to be inherited together Linked genes do not follow Mendel’s principle of independent assortment. Why? Discuss w/ partner.

6. The farther apart genes are from each other on a c’some, the less likely the will be inherited together.

8. A scientist named Thomas Hunt used Drosophila (fruit flies) to study genetics. Hunt discovered recombination frequency Recombination Frequency- % of recombinants that results from crossing over

9. The farther apart a gene is on a chromosome the less likely they will crossover together during meiosis Alleles “A” and “E” are less likely to crossover together b/c they are farther apart from each other

11. Copyright Pearson Prentice Hall Aristaless (no bristles on antenna) Chromosome 2Exact location on chromosome 13.0 Dumpy wing 0.0 48.5 Black body 54.5 Purple eye 67.0 Vestigial (small) wing 99.2 Arc (bent wings) 107.0 Speck wing

12. Gene map- shows the location of a gene on a chromosome. Gene maps can be used to calculate recombination frequencies. Genes that are close together have a low recombination frequency (crossovers are rare). Genes that are farther apart have a high recombination frequency (crossovers are likely).