A human cell contains how many chromosomes?

Appeared in: BSF Staff Nurse - 2015

Explanation

Human somatic (non-sex) cells are diploid (2n), containing a total of 46 chromosomes.
These 46 chromosomes are arranged into 23 pairs: 22 pairs of autosomes and one pair of sex chromosomes (XX for females, XY for males).
This diploid number is restored at fertilization when a haploid sperm (n=23) and a haploid egg (n=23) fuse to form a diploid zygote (2n=46).

Option A: This is the number of chromosomes in a human gamete (sex cell), which is a haploid (n) cell.
Option C: This is not the correct chromosome count for humans. It is the diploid number for other primates like chimpanzees and gorillas.
Option D: This number does not correspond to the chromosome count in any standard human cell type, either somatic or gamete.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain The number of chromosomes in a human somatic cell as background academic context rather than a clinical decision trigger.
Understanding the normal chromosome number is fundamental for recognizing genetic disorders. Deviations from 46, known as aneuploidy, cause conditions like Down syndrome (Trisomy 21, 47 chromosomes) or Turner syndrome (Monosomy X, 45 chromosomes).
Nurses may be involved in genetic counseling, explaining test results like karyotypes to patients and families, and caring for individuals with chromosomal abnormalities.
What if? If a patient's karyotype result was '47,XX,+21', the nurse would understand this indicates a female with Down syndrome, caused by an extra copy of chromosome 21, leading to a total of 47 chromosomes instead of the normal 46.

How to Approach the Question

First, identify the key terms in the question: 'human cell' and 'chromosomes'. Unless specified otherwise (like 'gamete' or 'sex cell'), 'human cell' refers to a somatic (body) cell.
Recall the fundamental concept of human genetics regarding chromosome numbers.
Differentiate between the diploid number (2n) for somatic cells and the haploid number (n) for gametes.
Select the option that corresponds to the diploid number for humans.
Eliminate options that represent the haploid number or are incorrect for the human species.

Concept Tested & Keywords

QRUqPeZMrTiQGH3Dl7T6pq

E6 Pathology-Vandana Puri & Kavita Gaur Textbook of Pathology and Genetics p. 472-474

E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 805-807

Practise the full BSF Staff Nurse - 2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.