Question

am 11 westion 7 a) A Drosophila species is diploid (2n=8), with letters H through J corresponding to four different chromosomes. In this species, how would you categorize the following genomes? For full credit include the ploidy formula and the technical name for the each. (4 points) a. HH I J KK b. HH III JJ KK c. HHHH III JJJJ KKKK d. HH II JJ KK b) What is the difference between trisomy and triploid and which is likely show the most deleterious effects of it chromosomal abnormality? (2 points) c) Which is worse, non-disjunction during Meiosis I or non-disjunction during Meiosis II, and why? (2 points) d) In terms of whole chromosome deletion or duplication, explain why the size of the chromosome matters? (2 points)

Answer 1

a)

• a- This condition is called monosomy the chromosome J is exist as single
• b- Trisomy- the chromosome I exist in 3 numbers instead of 2
• c- Tetrasomy- each chromosome have 2 pairs instead of one pair
• d- Normal chromosome

b)

The trisomy is a condition that an organism have an extra chromosome and the number of chromosome becomes 2n+1. where as triploidy is a condition where an organism having an entire extra set of chromosome. triploidy shows the most deleterious effect. the organism with triploidy usually do not survive.

c)

Non-dis junction is the failure of chromosomes or sister chromatids to separate properly during cell division, which leads to aneuploidy. meiosis 2 non-dis junction causes less aneuploidy than meiosis 1 non-dis junction. Non-dis junction in meiosis 1 causes 4 abnormal cells, where as in meiosis 2 non-dis junction 50 percent of the resulting cells will be normal, that is 2 normal and 2 abnormal cells.

d)

In deletion a part or the entire chromosome can be deleted results the decrease in the size of the genome. where as in duplication a length of DNA sequence is duplicates and results in extra genetic material. Whole chromosome deletion will cause the reduction in chromosome and the whole chromosomal duplication will results an extra chromosome.