Question Video: Defining the Term Autosome Biology

What is the meaning of the term autosome? [A] A chromosome that has been automatically replicated, ready for cell division [B] Any chromosome that has had a section removed [C] A chromosome that is found in the gametes of a human [D] Any chromosome that is not a sex chromosome (X or Y) [E] A chromosome that is automatically destroyed when damaged

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Video Transcript

What is the meaning of the term autosome? A chromosome that has been automatically replicated, ready for cell division. Any chromosome that has had a section removed. A chromosome that is found in the gametes of a human. Any chromosome that is not a sex chromosome, X or Y. Or a chromosome that is automatically destroyed when damaged.

This question asked us to select the most appropriate definition for the term autosome. So what is an autosome? In human somatic cells, that is, any cell except for egg cells in females and sperm cells in males, there are 46 chromosomes. The chromosomes are found in the nucleus of the cells and can be organized into 23 pairs. One chromosome in each pair was inherited from the biological mother and the other inherited from the biological father. In this diagram, fuchsia represents chromosomes inherited from the mother and orange from the father.

You will notice from the diagram that in 22 of these pairs, each chromosome in the pair is the same length as the other. We say they are homologous chromosomes. Homologous chromosomes are pairs of chromosomes of similar length. They have the same genes at each location. And following replication, the centromere will be at the same position on each chromosome in the pair. In this diagram, the homologous pairs one to 22 are autosomes. The final pair number 23 are not autosomes. These are the sex chromosomes.

There are two different sex chromosomes, the X chromosome and the Y chromosome. And although they do form a pair, you will notice that in our diagram they are not homologous. We have one X chromosome and one Y chromosome in our example. Let’s have a closer look at those sex chromosomes. The X chromosome is very large with around 900 genes. In comparison, the Y chromosome is very small with only around 55 genes. In our example, the cell contains one X and one Y chromosome. This means the cells belong to a male. In most female somatic cells, there are two X chromosomes. The sex chromosomes help determine the sex-specific features in both males and females.

We have just seen how chromosomes in cells can be autosomes or sex chromosomes. We now have enough information to answer our question. We know that any chromosome that is not an X or a Y is called an autosome. The correct answer to the question “What is the meaning of the term autosome?” is any chromosome that is not a sex chromosome, X or Y.

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