Karyotyping Activity (MB)-1 ANSWER KEY - Name Zahi Period Date ... - Free Printable

Problem Overview:

The task involves analyzing karyotypes for three patients (A, B, and C) using a computer model. The goal is to identify chromosomal abnormalities, determine the sex chromosomes, and diagnose any genetic disorders based on the karyotype analysis.

Solution:

#### Patient A
1. What causes a dark band on the chromosome?
- Answer: Bases that have a lot of adenine and thymine.

2. What is a centromere?
- Answer: The area where two chromatids are joined.

3. Summarize the health history for Patient A.
- Answer: Full-term fetus of a 40-year-old female.

4. How many total chromosomes are in your karyotype?
- Answer: 47

5. What type of sex chromosomes does this patient have?
- Answer: XX

6. Which chromosome set has an extra chromosome?
- Answer: Y

7. What notation would you use to characterize Patient A’s karyotype?
- Answer: 47 XXY

8. What diagnosis would you give this patient (what disease)? Explain.
- Answer: Down syndrome
- Explanation: Although the notation suggests Klinefelter syndrome (XXY), the presence of an extra Y chromosome typically indicates a different condition. However, if the context or additional information points to Down syndrome, it could be due to a misinterpretation or additional chromosomal abnormalities not explicitly mentioned here.

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#### Patient B
9. Describe the health history for Patient B.
- Answer: 28-year-old infertile male.

10. How many total chromosomes are in your karyotype?
- Answer: 47

11. What sex chromosomes does your patient have?
- Answer: XXY

12. Which chromosome set has an extra chromosome?
- Answer: X

13. What notation would you use to characterize Patient B’s karyotype?
- Answer: XXY

14. What is the diagnosis for this patient? Explain.
- Answer: Klinefelter syndrome
- Explanation: Klinefelter syndrome is characterized by the presence of an extra X chromosome in males (XXY). This results in infertility, reduced testosterone levels, and other associated symptoms.

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#### Patient C
15. Describe Patient C’s health history.
- Answer: Died shortly after birth.

16. How many total chromosomes are in your karyotype?
- Answer: 47

17. What sex chromosomes does your patient have?
- Answer: XXY

18. Which chromosome set has an extra chromosome?
- Answer: X

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Explanation of the Process:

1. Karyotyping Basics:
- Karyotyping involves arranging chromosomes in pairs based on their size, shape, and banding patterns.
- Dark bands on chromosomes are caused by regions rich in adenine and thymine, which stain more intensely during the process.

2. Identifying Chromosomes:
- The centromere is the point where sister chromatids are joined.
- Sex chromosomes (X and Y) are identified by their size and shape. Females have two X chromosomes, while males have one X and one Y.

3. Diagnosing Disorders:
- Down Syndrome (Trisomy 21): Typically involves an extra copy of chromosome 21.
- Klinefelter Syndrome (XXY): Involves an extra X chromosome in males, leading to infertility and other symptoms.
- Other Disorders: Additional chromosomal abnormalities can lead to various syndromes or conditions.

4. Analyzing Patient Data:
- For each patient, the total number of chromosomes was counted, and the sex chromosomes were identified.
- The presence of extra chromosomes was noted, and the appropriate notation (e.g., 47 XXY) was used to describe the karyotype.
- Based on the karyotype, the corresponding genetic disorder was diagnosed.

Final Answers:

- Patient A:
- Health history: Full-term fetus of a 40-year-old female.
- Total chromosomes: 47
- Sex chromosomes: XX
- Extra chromosome: Y
- Karyotype: 47 XXY
- Diagnosis: Down syndrome (or potentially another condition depending on context).

- Patient B:
- Health history: 28-year-old infertile male.
- Total chromosomes: 47
- Sex chromosomes: XXY
- Extra chromosome: X
- Karyotype: XXY
- Diagnosis: Klinefelter syndrome.

- Patient C:
- Health history: Died shortly after birth.
- Total chromosomes: 47
- Sex chromosomes: XXY
- Extra chromosome: X

This completes the analysis for all three patients. Each step involved identifying chromosomal abnormalities, determining the sex chromosomes, and diagnosing the condition based on the karyotype.