Question

All of these karyotypes are aneuploid, EXCEPT one of them. Which ONE is the exception? O A. (45,x) OB. (69, XXX) Oc (47,XXY) OD. (47, XY, +21) O E. (47, XYY)

Answer 1

1. FIRST QUESTION THE RIGHT ANSWER IS (69,XXX).

EXPLANATION

ANEUPLOIDY OCCURS WHEN ONE OR MORE CHROMOSOME NUMBER EITHER INCREASE OR DECREASE.

IN CASE OF (45,X) THIS KARYOTYPE IS DENOTED AS TOTAL NUMBER OF CHROMOSOME IN THE ORGANISM IS 45 WHERE A LACK OF OF X OR Y CHROMOSOME IS THERE.THIS AN EXAMPLE OF ANEUPLOIDY UNDER SINGLE MONOSOMY(2n-1) .

IN CASE OF (47,XXY) THIS KARYOTYPE IS DENOTED AS TOTAL NUMBER OF CHROMOSOME IN THE ORGANISM IS 47 WHERE AN EXTRA COPY OF X CHROMOSOME IS THERE THAT IS AN EXAMPLE OF ANEUPLOIDY UNDER TRISOMY (2n+1)

IN CASE OF (47,XY, +21) THIS KARYOTYPE IS DENOTED AS TOTAL NUMBER OF CHROMOSOME IN THE ORGANISM IS 47 WHERE AN EXTRA COPY OF 21 CHROMOSOME WHICH IS A TRISOMY OF 21 CAUSE DOWN SYNDROME . THAT IS AN EXAMPLE OF ANEUPLOIDY.

IN CASE OF (47,XYY) THIS KARYOTYPE IS DENOTED AS TOTAL NUMBER OF CHROMOSOME IN THE ORGANISM IS 47 WHERE AN EXTRA COPY OF Y CHROMOSOME IS THERE THAT IS AN EXAMPLE OF ANEUPLOIDY .

IN CASE OF (69,XXX) THIS KARYOTYPE IS DENOTED AS TOTAL NUMBER OF CHROMOSOME IN THE ORGANISM IS 69 WHICH REPRESENTS THAT THE COMPLETE SET OF CHROMOSOME IS MORE THAN TWICE. HERE IT IS TRIPLOIDY (3n) and here n=23. THUS (69,XXX) THIS KARYOTYPE IS NOT AN EXAMPLE OF ANEUPLOIDY BUT AN EXAMPLE OF EUPLOIDY.

2) THE RIGHT ANSWER IS 3RD ARROW OR ARROW 3 IS NOT A CHECK POINT IN CELL CYCLE .

EXPLANATION

THERE ARE THREE TYPES OF CHECKPOINTS PRESENT IN THE CELL CYCLE. FIRST IS METAPHASE CHECKPOINT AFTER WHICH THE CELL CAN ENTER IN G1 PHASE. SECOND IS G1 CHECKPOINTS AFTER WHICH THE CELL CAN ENTER IN THE S-PHAGE. AND THE LAST CHECKPOINT IS G2 AFTER THAT THE CELL CAN ENTER IN THE M-PHASE . SO IN THE S-PHASE THERE IS NO CHECKPOINTS IN THE CELL CYCLE.