Diploid Cell Definition
In the nucleus of a diploid cell, there are two full sets of chromosomes, while haploid cells only have one copy. The gametes (sperm and egg cells) are the only haploid cells, whereas the majority of human body cells are diploid.
In diploid cells, chromosomes are organised into homologous pairs. The total number of chromosomes in a cell is known as the diploid chromosomal number (2n). In the case of humans, 2n = 46, implying that a diploid human cell has 46 chromosomes.
What is a Diploid Cell?
A diploid cell is one in which the nucleus contains the whole set of chromosomes. Each chromosome is duplicated in a diploid cell, which is structured into homologous pairs. While these homologous pairs are not identical, they do’match,’ meaning they include the identical genes at the similar loci and have the similar shape and size.
Homologous chromosomal pairs include DNA from both of the organism’s parents; the father contributes one and the mother contributes the other.
How Many Chromosomes Are in a Human Diploid Cell?
The number of chromosomes in a diploid cell’s nucleus is known as the diploid chromosomal number (typically written as 2n). There are 46 chromosomes in human diploid cells, with 23 homologous chromosomal pairs. As a result, human cells have 2n = 46 diploid chromosomes.
Sex chromosomes are two of the chromosomes present in human cells, and they define the organism’s sex. Males are born with one X and one Y chromosome (XY), whereas females are born with two X chromosomes (XX). This is the sole instance in which a homologous pair does not contain two copies of the same chromosome.
Because various species have varying numbers of chromosomes, the number of diploid cells varies greatly across organisms. Garlic, for example, has a diploid number of 2n = 16, whereas dogs have a diploid number of 2n = 28, and elephants have a diploid number of 2n = 56.
Examples of Diploid Cells
All body cells (affectionately referred to as “somatic cells”) are diploid. As a consequence, the vast majority of human cells are diploid, which means they have all of their chromosomes. The following characteristics are seen in human diploid cells:
- Muscle cells
- Skin cells
- Blood cells
- Nerve cells
- Bone cells
The gametes, or sex cells, are the only human cells that are haploid (i.e., have just one pair of chromosomes). Humans have n = 23 haploid chromosomes.
During sexual reproduction, the haploid sperm and egg cells join together to produce a single diploid cell (also called a zygote). The diploid zygote will contain genetic material from both parental sex cells, including 50% egg cells and 50% sperm cells.
Diploid Cell Reproduction
Mitosis is the process through which diploid cells proliferate. During mitosis, the diploid parent cell replicates all of its DNA, culminating in a new set of identical chromosomes. When a cell divides, it gives its whole genome to the newly formed daughter cell, producing a genetically similar clone of the original cell.
The Diploid Life Cycle
Sexually reproducing organisms, like humans, for example, have a mostly diploid life cycle and devote the bulk of their existence to being diploid adults. Only the haploid gametes are haploid, so almost all of their cells are diploid. Diploid organisms use meiosis, a kind of cell division that creates four non-identical cells, to produce haploid sex cells when they achieve sexual maturity. The number of chromosomes in these non-identical daughter cells is half that of the parent cell.
Two haploid gametes unite to form a diploid zygote after fertilisation. The zygote then splits into two identical daughter cells by mitosis. The zygote ultimately grows into a diploid adult by repeated rounds of cell division, and the cycle continues.
Diploid Cells vs. Haploid Cells
The table below summarises the major distinctions between haploid and diploid cells.
|Diploid Cells||Haploid Cells|
|Chromosome Number||Contain two sets of chromosomes (2n)||Contain a single set of chromosomes (n)|
|Reproduction||Reproduce by mitosis||Reproduce by meiosis|
|Examples||Somatic (body) cells, e.g., skin cells, nerve cells, muscle cells, etc.||Gametes, e.g., sperm and egg cells|