Video Transcript
A koala has eight chromosomes in a haploid cell. How many chromosomes will a diploid cell from this organism contain?
In eukaryotic organisms, molecules of DNA are coiled and condensed into structures
called chromosomes. The DNA of these chromosomes contains genes, which determine the organism’s genetic
traits. Most body cells in an organism are diploid. This means the cell has two complete set of chromosomes that are arranged into
pairs. For instance, a human body cell contains 46 chromosomes in total, which are arranged
as 23 pairs.
Sex cells, also called gametes, are referred to as haploid. The ha- part of the word haploid refers to the word half. Therefore, we know that a haploid cell will contain half the number of chromosomes of
a diploid cell of the same organism. Instead of having two sets of chromosomes, haploid cells will only have one set. Human gametes, the sperm and egg cell, contain 23 chromosomes. This is very important for the process of reproduction. So when a sperm and egg cell combine during fertilization, the resulting zygote will
have 46 chromosomes.
So to convert between haploid and diploid cells, we simply need to double the number
of chromosomes. If a haploid cell of a koala has eight chromosomes, the number of chromosomes in a
diploid cell from the same koala must be double this number. Therefore, a diploid cell of a koala will contain 16 chromosomes.
