The Chromosomal Theory of Inheritance:

2. The Chromosomal Theory of Inheritance: • Chromosomes and genes are present as ______________________ • homologous chromosomes ___________during meiosis • ________________ restores chromosome number to ____________________ • The _________________________ claims it is the chromosome that ___________ and _________independently.

3. Gene Linkage • In flies ________________ is dominant to ______________, and long wings _____________ are dominant to vestigial wings _____. • What is the expected phenotypic ratio from a cross between a heterozygous gray, heterozygous normal winged fly with a black vestigial fly? • ________________________ • But what he got was…..

5. What explains the non-Mendelian results? • __________________________________ • The traits are located on the _________________ and are _________ to each other that they are said to be ___________. • If the traits are linked, then all of the offspring should resemble the parental types, black vestigial or gray normal. • How did we get the recombinant traits of black, normal and gray vestigial?

8. Using Recombination Frequency to Map Traits • _______________________ between black and vestigial traits is __________ • Recombination frequency between cn and black is __________ • Recombination between cn and vg is _________________ • Map these traits on the chromosome.

10. Determine the order of genes along a chromosome based on the following recombination frequencies: • A - B 8% • A - C 28% • A - D 25% • B - C 20% • B - D 33% • _______________

11. Chromosome Types • Autosomes are the first ________________________________________________________________ • Autosomes do not determine ________ • Sex chromosomes are the _________ • In males, the sex chromosomes are _____ • In females, the sex chromosomes are _________

13. Sex Linked Traits • Drosophila eye color is linked on the _______________________ • Females carry ____________ of the gene while males have only _________ • The _____ chromosome does not carry many sex-linked traits at all! • White eyed females carry the recessive allele on _______________ • Red eyed females can be _______________________ • White eyed male cannot hide the trait since he has only one _______.

14. Morgan and Linked Traits

17. Who is responsible when a boy inherits a sex linked condition? • A carrier of a condition is heterozygous for the trait, so only____________ can carry sex linked traits.

18. Human Sex-linked traits: • Red-green colorblindness • Hemophilia

20. X Inactivation in Females • How does an organism compensate for the fact that females have a double dosage of sex-linked genes, while males have only one? • The inactivation is random and approximately half the X’s from Mom and half the X’s from Dad will inactivate

21. The calico cat is the result of multiple alleles on the X chromosome combined with X inactivation. • One allele causes orange fur and the other causes black fur. • The male cat will be either orange or black. • Only a heterozygous female will be calico with regions that are orange and regions that are black based on the X inactivation.