In this video, we're going to distinguish between haploid and diploid cells, but first, we need to define the term cell ploidy. Cell ploidy is defined as the number of copies or sets of specific genes or chromosomes found in a cell. For the purposes of this course, there are really 2 specific terms that you should be familiar with, which we have numbered down below, number 1 and number 2.
The very first term that you should know is haploid, commonly symbolized with the letter n. Haploid cells are going to be cells that only have one copy of each gene or chromosome. Now, the second term that you should know is diploid, and the term diploid is commonly abbreviated using the symbol 2n. Diploid means that the cell is going to have 2 copies of each gene or chromosome. Of these two copies, one copy is going to be inherited from each of the parents. One copy would be inherited from the mother and the other copy would be inherited from the father.
One way that helps me remember the difference between haploid and diploid is that the root 'di' in diploid means 2. Diploid means that it's going to have 2 copies of every gene or chromosome. The root 'haplo' in haploid can remind you of 'half.' Haploid cells are going to have half the number of chromosomes as diploid cells. So, they have one copy of each gene or chromosome instead of having two copies.
If we take a look at our image down below, we can further distinguish between haploid and diploid cells. Notice over here on the left-hand side we're showing you a haploid cell, commonly abbreviated with just the letter n. The haploid cell has one copy of the tall chromosome in blue and one copy of the short chromosome in a reddish color.
Now, if we compare that to the diploid cell over here on the right-hand side, again, diploid is commonly abbreviated with the symbol 2n. Notice that there are 2 copies of the tall chromosome: one copy in blue inherited from the father, and another copy of the tall chromosome inherited from the mother in reddish-pink. There are also 2 copies of the short chromosome: one copy in blue inherited from the father and one copy in reddish-pink inherited from the mother. So, there are 2 copies of every chromosome, and of course, there are genes on the chromosome, so there are also 2 copies of every gene in the diploid cell. Here you can see a cell, and its nucleus, with the diploid number of chromosomes here.
Distinguishing between haploid and diploid cells is going to be very important as we move forward in our course and talk about meiosis. This here concludes our brief introduction to haploid versus diploid cells, and we'll be able to get some practice applying these concepts as we move forward in our course. So, I'll see you all in our next video.