Liver cells and cheek cells fundamentally share the same set of chromosomes and, therefore, the same complete genetic instructions. Both are categorized as somatic cells (body cells, not sex cells), meaning they contain identical genetic content. This shared genetic material is a consequence of their common origin from the initial fertilized egg, or zygote, which contains the entire blueprint for the organism.
The Genetic Blueprint of Somatic Cells
All body cells, including hepatocytes (liver cells) and buccal epithelial cells (cheek cells), are somatic cells and possess the diploid number of chromosomes. In humans, this diploid number is 46, arranged in 23 pairs, with one set inherited from each parent. This complete collection of genetic material is referred to as the organism’s genome, and it is identical across all somatic cells.
The mechanism that ensures this genetic consistency is a type of cell division called mitosis. During mitosis, a parent cell replicates its DNA and then divides to produce two genetically identical daughter cells. This process guarantees that both the newly formed cheek cell and the new liver cell receive an exact, full copy of the 46 chromosomes present in the original dividing cell.
Since all cells in the body arose from the single zygote through repeated rounds of mitosis, they all carry the same complete genetic library. The 22 pairs of autosomes and the single pair of sex chromosomes (XX or XY) are all present in both cell types.
How Cells Look Different Despite Identical DNA
The difference in function and appearance between a liver cell and a cheek cell is explained not by the DNA sequence itself, but by cell differentiation and gene expression. Differentiation is the process by which a cell becomes specialized to perform a specific function, such as the liver’s role in detoxification or the cheek cell’s role in protection.
This specialization is controlled by regulatory mechanisms that determine which genes are “turned on” or “turned off” within the cell. Gene expression is the process where the information stored in DNA is converted into instructions for making proteins, which then determine the cell’s structure and function. A hepatocyte requires a specific set of enzymes for metabolism and detoxification, so the genes coding for those proteins are highly active.
Conversely, a cheek cell, which primarily provides a protective lining, expresses genes related to structural proteins like keratin, while the detoxification genes remain silent. This selective reading of the shared genetic code is what creates the vast diversity of cell types in the body.
Key Variations in Chromosome Content
While the foundational genetic information is the same, mature liver cells can exhibit notable variations in their chromosome number, which are exceptions to the standard diploid rule. A significant portion of mature hepatocytes are polyploid, meaning they contain multiple complete sets of chromosomes, such as four sets (tetraploid) or even eight sets (octaploid). This condition, known as polyploidy, often arises because the cell replicates its DNA but then fails to complete cytokinesis, the final step of cell division where the cytoplasm divides.
Many hepatocytes are also binucleated, possessing two separate nuclei within a single cell membrane. These binucleated cells typically contain a tetraploid amount of DNA split between the two nuclei, each holding a diploid set of chromosomes. These variations in ploidy and nuclearity are common features of adult liver tissue, and they are thought to enhance the liver’s metabolic capacity and ability to regenerate.
Other exceptions to the 46-chromosome rule exist, such as mature red blood cells, which completely lack a nucleus and chromosomes, or cells with pathological variations, like many cancer cells that often show abnormal chromosome numbers (aneuploidy). Therefore, while the genetic information is identical between a liver cell and a cheek cell, the physical number of chromosomes can differ in the liver cell due to these specialized adult cell variations.