Homework SourseThe specification of the anteriorposterior axis in Drosophil
The specification of the anterior-posterior axis in Drosophila embryos is initially controlled by various gene products that are synthesized and stored in the mature egg following oogenesis. Mutations in these genes result in abnormalities of the axis during embryogenesis. These mutations illustrate maternal effect.
Part A
How do such mutations vary from those produced by organelle heredity?
Select the three correct answers.
Part B
What are the expected outcomes of parallel crosses involiving mutant gnes that contrast maternal effect and organelle heredity?
What are the expected outcomes of parallel crosses involiving mutant gnes that contrast maternal effect and organelle heredity?
| A)In maternal effect, both parents transmit information on genes in the nucleus that determines the offspring\'s phenotype. |
| B)Anterior/posterior and dorsal/ ventral orientations are among the earliest to be established, and in organisms in which their study is experimentally and/or genetically approachable, they often show considerable maternal influence. |
| C)Maternal effects last more than one generation. |
| D)Developmental phenomena that occur early are more likely to be under maternal influence than those occurring late. |
| E)Developmental phenomena that occur late are more likely to be under maternal influence than those occurring early. |
| F)Maternal-effect genes yield products that are not carried over for more than one generation, as is the case with organelle and infectious heredity. |
Solution
A)In maternal effect, both parents transmit information on genes in the nucleus that determines the offspring\'s phenotype.
D)Female Aa × male aa all offspring of the A phenotype.
Female aa (from the offspring of the above cross) × male Aa all offspring of the a phenotype.
| A)In maternal effect, both parents transmit information on genes in the nucleus that determines the offspring\'s phenotype. D)Female Aa × male aa all offspring of the A phenotype. |
