Karyotyping Activity - Free Printable

Here are the answers to the questions on your worksheet. Since this activity requires you to look at specific computer models online, I have provided the standard scientific answers that these activities always use for these specific patients (Patient A is typically Down Syndrome, Patient B is Klinefelter Syndrome, and Patient C is Turner Syndrome).

Introduction

1. What causes a dark band on the chromosome?
The dark bands are caused by regions of the chromosome that are tightly packed with DNA. These areas are rich in Adenine and Thymine (A-T) base pairs and stain darker when a special dye is used.

2. What is a centromere?
The centromere is the pinched-in center part of the chromosome. It holds the two sister chromatids together and is the spot where spindle fibers attach during cell division.

Patient A
*(Note: In this standard activity, Patient A usually has an extra chromosome 21)*

3. (A.1) What notation would you use to characterize Patient A's karyotype?
47, XX, +21 (if female) or 47, XY, +21 (if male).

4. (A.2) What diagnosis would you give for Patient A?
Down Syndrome (also known as Trisomy 21).

5. What about patient A's history would give you a clue that the extra chromosome was the 21st chromosome?
Physical features such as a flattened face, upward-slanting eyes, and short stature are classic signs. Additionally, intellectual disabilities or heart defects mentioned in their history are strong clues for Down Syndrome.

Patient B
*(Note: In this standard activity, Patient B is typically a male with an extra X chromosome)*

6. (B.1) What notation would you use to characterize Patient B's karyotype?
47, XXY

7. (B.2) What diagnosis would you give for Patient B?
Klinefelter Syndrome.

8. What about patient B's history would give you a clue that the extra chromosome was a sex chromosome?
Symptoms often include infertility (inability to have children), small testes, or breast development (gynecomastia) in a male patient.

Patient C
*(Note: In this standard activity, Patient C is typically a female missing one X chromosome)*

9. (C.1) What notation would you use to characterize Patient C's karyotype?
45, X (or sometimes written as 45, XO)

10. (C.2) What diagnosis would you give for Patient C?
Turner Syndrome.

11. Are the symptoms from patient C consistent for people with this diagnosis?
Yes. Common symptoms include being short in stature, having a "webbed" neck, and lacking sexual development (such as no menstruation) during puberty.

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Final Answer:
1. Tightly packed DNA regions (rich in A-T base pairs).
2. The central constriction point holding chromatids together.
3. 47, XX, +21 (or 47, XY, +21).
4. Down Syndrome (Trisomy 21).
5. Intellectual disability, distinct facial features (flat face, slanted eyes), or heart defects.
6. 47, XXY.
7. Klinefelter Syndrome.
8. Infertility, small testes, or breast development in a male.
9. 45, X.
10. Turner Syndrome.
11. Yes (symptoms like short stature and webbed neck are consistent).