Mendelian genetics II

Question 1

Morgan’s experiments:

Answer 1

• Drosophila melanogaster
• multiple yrs of breeding - variation in trait (eye colour)
• followed 3:1 ratio
• all F2 females had red eyes, males had 1/2 of red/white
• on sex chromosome

Question 2

x- linked recessive genes:

Answer 2

• fathers pass X-linked alleles to daughters only
• mothers pass to both
• males more likely to have X- linked disorders

Question 3

x inactiviation in females:

Answer 3

• one is inactivated during development of embryo (females)
• inactive X chromosome (Barr body) and genes aren’t expressed
• embryonic cells have random mosaic of inactivated X chromosomes

Question 4

linkage:

Answer 4

• closer 2 genes are on chromosome, more likely inherited together
• and linked
• deviates from Mendel’s Law of independent assortment

Question 5

principle of segregation:

Answer 5

• only 1 chromosome from pair of homologous chromosomes is transmitted to offspring