chromosomes. How many chromosomes will be found per cell in each of the followin
ID: 150540 • Letter: C
Question
chromosomes. How many chromosomes will be found per cell in each of the following mutants in this species? a. Monosomic b. Autotriploid c. Autotetraploid d. Trisomic e. Double monosomic f. Nullisomic g. Auto pentaploid h. Tetrasomic 6. Species W is diploid (2n-8) with chromosomes AABBCCDD; related species X is diploid (2n-8) with chromosomes MMNNOOPP. What type of chromosome mutations do individual organisms with the following sets of chromosomes have? a. AAABBCCDD b. c. AABBCDD e. AAABBCCDDD f. AABBDD g. AABBCCDDMMNNOOPP h. AABBCCDDMNOPExplanation / Answer
a) Monosomic individual will have one chromosome less than the normal number because one of the chromosome lacks its homologous counterpart.. Therefore 11 chromosomes will be found per cell.
b) Autotriploid will have one extra set of chromosome. One set of chromosome i.e n contains 6 chromosomes. An autotriploid is 3n and will have 3 x6 = 18 chromosomes.
c) Autotetraploid has 4n chromosomes. Therefore an autotetraploid cell will have 4 x 6 =24 chromosomes.
d) trisomic cell has 3 copies of a single chromosome. This results in addition of one extra chromosome to the normal set. Trisomic cell will have 2n +1 =2x 6 +1 = 13 chromosomes
e) In double monosomic cells, two different chromosomes do not have their homologous counterparts. Double monosomic individual have 2n-1-1 =2 x 6 -1 -1 =10 chromosomes.
f) In nullisomy a chromosome pair is missing. Therefore a nullisomic cells will have 2n-2 =2x 6 -2 = 10 chromosomes
g) autopentapolid will have 5n set of chromosomes i.e 5 x 6 =30 chromosomes per cell.
h) In tetrasomy, 4 copies of a particular chromosome are present i.e 2 extra copies. Tetrasomic cells will have 2n+2 =2x 6 +2 =14 chromosomes per cell
6 a) There are 3 copies of chromosome A. A normal cell is diploid and contains two copies of chromosome A . Therefore this organism is trisomic (2n+1)
b) It contains 4 copies of chromosome O. Normal cell is diploid and contains two copies of each chromosome. Therefore this organism is tetrasomic (2n+2)
c) It contains only a single copy of chromosome C. Normal cell is diploid and contains two copies of each chromosome. Therefore this organism is monosomic (2n-1)
d) It contains one extra set (n) of chromosome ABCD. Normal cells are AABBCCDD. This is a condition of change in ploidy of cells as whole set of chromosome is added. Since the same chromosomes are added, this is a result of multiplication of the same genome. Therefore the inidividual is autotriploid having 3 set of chromosome
e) One extra copy of each chromosome A and D is present. Two different chromosomes A and D have three copies . This condition is double trisomy (2n+1+1)
f) It lack both copies of chromosome C . This is a conditon of nullisomy as cells lack chromosome C
g) It contains 2 sets of chromosome from species W and another 2 sets from species X. It may have resulted from gametes from the two different species and then their duplication
Species W Species X
AABBCCDD MMNNOOPP
Gametes : ABCD MNOP
Fusion: ABCDMNOP
Doubling : AABBCCDDMMNNOOPP
This condition is called allopolyploidy. Here in total 4 sets of chromosomes are present (2 from species X and 2 from species Y). Therefore this individual is allotetraploid.
h) It contains 3 sets of chromosomes (2 from species W and one from species X). This is also a result of fusion of gametes from W and X. The chromosome of W doubled whereas that of X did not double. Therefore this individual is allotriploid.
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