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Question Video: Defining the Function of Chromosomes Biology

Chromosomes are formed from the nucleic acid DNA. What is the primary function of these chromosomes? [A] To keep the contents of the nucleus and the cytoplasm separate. [B] To act as the site of cellular respiration. [C] To provide essential nutrition for the cell. [D] To carry genetic information and allow it to be passed from parent to offspring.

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Video Transcript

Chromosomes are formed from the nucleic acid DNA. What is the primary function of these chromosomes? To keep the contents of the nucleus and the cytoplasm separate. To act as the site of cellular respiration. To provide essential nutrition for the cell. Or to carry genetic information and allow it to be passed from parent to offspring.

Let’s start by deciphering the information in the question and what we already know about the structure and function of chromosomes. Each chromosome is a large unit used by cells to organize and store their DNA. You can see a chromosome on the diagram here. Chromosomes can be made up of one or two chromatids. In this case, it consists of two chromatids. If this chromosome was to unravel and if we had a very sophisticated microscope so we could zoom in really close on it, we might be able to see the DNA like it’s shown in the side of the diagram here.

DNA is the molecule that carries the genetic instructions for life. It can be passed on from a parent to their offspring. DNA takes the shape of a double helix. DNA is found in the form of these chromosomes in the nucleus of almost all eukaryotic cells. This nucleus is surrounded by a membrane called the nuclear envelope, which controls what can enter and leave the nucleus. As the nuclear envelope is a membrane, it also acts to separate the nucleus and its contents from that of the cytoplasm. Now that we know a little bit more about chromosomes and their function, let’s try to work out the correct option using the process of elimination.

When a question asks for the primary function of something, several of the answers may seemingly be correct. We are looking for the option which defines the function of chromosomes best. So all answers must be carefully scrutinized. One of our options refers to keeping the contents of the nucleus and the cytoplasm separate. This is a role of a membrane, and in this specific case, it is referring to the nuclear envelope. Chromosomes, however, are not membranes, and therefore this option can be eliminated.

Another of our options refers to the site of cellular respiration. Cellular respiration does not occur in the nucleus of eukaryotic cells but in a different organelle called a mitochondrion, which is pictured here. This is, therefore, not a function of a chromosome. The next option refers to another key life process other than respiration, which is obtaining nutrition. Some eukaryotic organisms can obtain nutrition from structures within their own cells, such as plants, which have chloroplasts in their cells, like the one pictured here.

Plants carry out a process called photosynthesis, using light energy to synthesize glucose in these chloroplasts. Not all eukaryotes have chloroplasts, so not all of them can obtain nutrition within their own cells, however. This cannot therefore be a role of a structure common to all eukaryotic organisms, such as the chromosome, so this option is also incorrect.

This leaves us with the option that defines the two main aspects required when defining the function of chromosomes that they hold genetic information in the form of DNA and that this genetic information is heritable. So it could be passed from a parent onto their offspring. So, the primary function of chromosomes is to carry genetic information and allow it to be passed from a parent to offspring.

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