Please explain how the answers were obtained as simply as possible. Bonus: Answe
ID: 262478 • Letter: P
Question
Please explain how the answers were obtained as simply as possible.
Bonus: Answer r only onc of the following two questions. If you answer both questions, you will receive zero credit for the bonus. The response to the bonus should be after the responses to your regular questions. 1. (5 points) In a mutant Jimson weed (Datura stramonicum), chromosome B is present in three copies whereas all other chromosomes are in the disomic (diploid) state. Jimson weed pollen grains do not tolerate multiplc chromosomes and are incapable of fertilization. However, the ovum is capable of fertilization in the trisomic state. If you seli-fertilize a trisomic Jimson weed plant, what zygotes would be formed? Tell which zygotes are diploid and which are trisomic. Assume that only the univalent mode occurs during mciosis. Please use the chart as a guide for writing your answer in your blue book. Male gametes 2. (10 points) Down's syndrome can result from a Robertsonian tranlsocation at a Frequency of 9/100 live births. This type of Down's syndrome usually occurs in mothers that are less than 30 years of age. The Robertsonian translocation that leads to Down's syndrome occurs between chromosomes 21 and 14. During Meiosis, three possible pairing configurations can be observed between the 14/21 translocated chromosome and the normal homologues. Think about how these pairings might occur and draw only one of the three possible pairing draw your pairing arrangement with respect to the equator of the cell at metaphase. Your drawings should be unambiguous and concise. 44214Explanation / Answer
1.ANS:
B1
B2
B3
B1B2
B1B1B2
B1B2B2
B1B2B3
B2B3
B1B2B3
B2B2B3
B2B3B3
B1B3
B1B1B3
B1B2B3
B1B3B3
B1
B1B1
B1B2
B1B3
B2
B1B2
B2B2
B2B3
B3
B1B3
B2B3
B3B3
Thus, first three rows indicate trisomy condition, while remaining three lines indicate diploid condition zygotes.
B1
B2
B3
B1B2
B1B1B2
B1B2B2
B1B2B3
B2B3
B1B2B3
B2B2B3
B2B3B3
B1B3
B1B1B3
B1B2B3
B1B3B3
B1
B1B1
B1B2
B1B3
B2
B1B2
B2B2
B2B3
B3
B1B3
B2B3
B3B3