A normal human cell has how many chromosomes?

Appeared in: GMCH Chandigarh - 2022

Explanation

Normal human somatic (body) cells contain a total of 46 chromosomes.
This is known as the diploid number (2n), which consists of 23 pairs of chromosomes.
These pairs are made up of 22 pairs of autosomes (non-sex chromosomes) and one pair of sex chromosomes (XX in females, XY in males).

Option A: This is the haploid (n) number of chromosomes, which is found only in gametes (sperm and egg cells), not in a typical somatic cell.
Option C: This is not a normal chromosome count for any human cell. An abnormal number of chromosomes is known as aneuploidy and is associated with genetic disorders.
Option D: This is the chromosome count for other species, such as great apes or potatoes, but it is not the correct number for humans.

Visual 1: Diagram: Comparison of a diploid somatic cell (46 chromosomes) and a haploid gamete (23 chromosomes) to illustrate the difference.
Visual 2: Illustration: A human karyotype showing the 23 pairs of chromosomes, clearly labeling the 22 autosome pairs and the XY sex chromosome pair.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Human Chromosome Number (Diploid vs. Haploid) as background academic context rather than a clinical decision trigger.
Understanding the normal chromosome number (46) is fundamental for identifying genetic disorders caused by aneuploidy (an abnormal number of chromosomes).
Nurses play a role in genetic counseling and patient education, explaining the significance of prenatal screening tests that can detect chromosomal abnormalities like Down syndrome (47 chromosomes) or Turner syndrome (45 chromosomes).
What if? If the question specified a cell with an extra chromosome 21, the answer would be 47, which is characteristic of Down syndrome.

How to Approach the Question

First, identify the key terms in the question: 'normal human cell' and 'chromosomes'.
Recognize that 'human cell' in a general context refers to a somatic (body) cell, not a sex cell, unless specified.
Recall the standard diploid (2n) number of chromosomes for human somatic cells.
Differentiate the diploid number from the haploid (n) number, which applies to gametes (sperm and eggs).
Evaluate the given options: 46 is the diploid number, and 23 is the haploid number. Eliminate the other incorrect values.
Select the option corresponding to the diploid number for a normal somatic cell.

Concept Tested & Keywords

QtrVCHUT3VDR_EDFi37syc

Practise the full GMCH Chandigarh - 2022

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