The karyotype below depicts a mutation on chromosome #23. This type of mutation is due to ______.
a
nondisjunction
b
translocation
c
down syndrome
d
deletion
The karyotype in the question hasn't been provided, so I cannot directly visualize the mutation you are referring to on chromosome #23. However, I can explain what each of the choices would mean in the context of a karyotype.
a. Nondisjunction refers to the failure of chromosomes to separate properly during cell division. If nondisjunction occurred with chromosome #23, which is one of the sex chromosomes, you might see an individual with an abnormal number of sex chromosomes (e.g., XXY in Klinefelter syndrome, or XO in Turner syndrome).
b. Translocation occurs when a portion of one chromosome breaks off and attaches to another chromosome. A translocation on chromosome #23 would show an abnormal connection between it and another chromosome on a karyotype.
c. Down syndrome is characterized by an extra copy of chromosome #21, not #23. The karyotype of an individual with Down syndrome would have three copies of chromosome #21 (trisomy 21).
d. Deletion is the loss of a portion of a chromosome. If a deletion mutation were present on chromosome #23, it would indicate that a part of the chromosome is missing on the karyotype.
As the karyotype is not visible, I can't determine the exact mutation described. Based on the options given, correct identification relies on visually examining the karyotype:
- If there is an abnormal number of sex chromosomes, the answer would be nondisjunction (a).
- If a piece of chromosome #23 is swapped with another chromosome, it would be translocation (b).
- If chromosome #23 has missing pieces, it would be deletion (d).
Option c (Down syndrome) is not applicable to a mutation on chromosome #23 because Down syndrome specifically involves chromosome #21.
Since the specific mutation on chromosome #23 is not described or visible here, you would need to view the karyotype to determine the correct answer.