A person whose cells all contain a chromosome number of 2n+1 most likely has what type of condition?
A. Monosomy
B. Trisomy
C. Cancer
D. Obesity
E. None, this is the normal chromosome number for humans.
Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?
Gather Content
· What do you know about the number of chromosomes in a human cell? How does it relate to the question?
Consider Possibilities
· What other information is related to the question? Which information is most useful?
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
B. Trisomy
Clarify Question
· What is the key concept addressed by the question?
o The question asks about a cell with 2n+1 chromosomes.
· What type of thinking is required?
o You are being asked to apply your knowledge of the normal number of chromosomes in a cell.
· What key words does the question contain and what do they mean?
o 2n+1 – a diploid cell is 2n, so a cell with 2n+1 chromosomes has one extra chromosome.
Gather Content
· What do you know about the number of chromosomes in a human cell? How does it relate to the question?
o The normal chromosome number for humans is 2n, where n = 23 for the number of different types of chromosomes that human cells contain. 2n + 1 indicates that the individual has the diploid number of chromosomes (i.e., 46) plus one additional chromosome.
Consider Possibilities
· What other information is related to the question? Which information is most useful?
o Monosomy would be 2n - 1, because this refers to a condition where one chromosome is missing.
o While cancer cells can sometimes gain or lose one or more chromosomes, this would not affect all the cells in the organism - only the cancer cells.
o This chromosome number is not relevant to obesity.
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o The presence of an extra chromosome indicates that they most likely have an extra copy of one chromosome, which is how trisomy is defined. Because this is in all cells, this is most likely a case of trisomy
.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
o This question asked you to apply your understanding of the number of chromosomes in a normal cell to define how an individual 2n+1 chromosomes would be classified. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that 2n-1 was a trisomy and not a monosomy? Did you think that a 2n+1 number of chromosomes in all cells would contribute to cancer or obesity?
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