How Many Chromosomes Are In A Normal Human Cell?

The human body is made up of thousands of cells, and each of these contains a thing called chromosomes. We know that you heard the term in science class, but you wouldn’t be the only one to forget what they were as soon as you left school!

Chromosomes are threads of DNA found in the nucleus of each human cell. DNA is genetic information that makes the person who they are. They can determine your traits, such as your eye color and blood type.

Humans and animals all have chromosomes within their cells, but the number of chromosomes differs greatly. So, how many chromosomes do humans have? We’ll find out today in this article. 

How many chromosomes do humans have? 

In total, a human will have 23 pairs of chromosomes. This means that they have 46 chromosomes altogether. Chromosomes come in pairs, so no human or animal will normally have an odd number of chromosomes. For example, you can find four pairs of chromosomes in a fruit fly, and 12 in a rice plant.

Your four-legged furry friend has 39 pairs of chromosomes, too. It’s interesting to many people that a dog would have more chromosomes than a human, However, it is not as farfetched as people might think as dogs have many of the same biological functions as humans do.

What exactly is a chromosome? 

The chromosomes can be found inside the nucleus of the human cell. The chromosomes are made from proteins with one strand of DNA. Your parents will have both passed on their DNA to you, and your chromosomes will contain instructions on how to make you perfectly unique.

The word chromosomes comes from the word ‘Chroma’, which is Greek for color, and ‘Soma’ which translates to the body. Scientists gave the name to chromosomes because they are bodies that can be stained with colored dyes while being used in research.

What is the chromosome job? 

Chromosomes keep DNA strands wrapped around proteins, which are shaped like spools, called histones. This keeps the DNA strands compact enough so that they can fit inside of the cells. Without these proteins, the DNA wouldn’t be able to squeeze inside the tiny cell.

If you were to unwind all of your DNA strands inside of your body and placed them together, they would be measurable to six feet. That’s a lot of DNA! As living beings, our cells are always growing and replenishing themselves.

They do this by splitting into new, healthier cells. The old and tired cells are then allowed to retire and not work as hard to keep your body healthy. The nuclei of the new cell and the old cell need to work together to copy the DNA so that your body still has the strand of your identity.

Chromosomes are an essential part of this process. Without the chromosome, it would be much more difficult for the cells to copy the DNA. While the chromosomes make the process easier, they still do make mistakes from time to time.

Differences in your chromosomes, whether it be the number of them or the structure, can be the cause of serious health complications. An example of this is leukemia, a form of cancer that is caused by a defective chromosome made up of broken chromosomes.

Your reproductive cells also contain chromosomes, and it is essential that these have the right number and structure too. If this isn’t the case, the offspring might not develop properly. Down Syndrome is an example of this, as people with the condition have an extra copy of the 21st chromosome, rather than only two copies that there should be.

How are chromosomes inherited?

We have two pairs of each chromosome in our cells. One copy of the chromosomes will be given from the mother, and one copy is by the father. So, a couple’s offspring will have a copy of both their mother and father’s DNA. This is why you have traits from both of your parents.

The only difference with the pattern of inheritance is that the egg cell is the only one to house mitochondria during fertilization. Within the mitochondria is a small chromosome which allows the DNA to be inherited from the mother instead of the father.

There have been some cases in which issues such as diabetes and hearing impairments have been associated with the DNA inside of the mitochondria. However, this is not always the case.

Do women have different chromosomes than females? 

Yes, men and women have different sex chromosomes, but this is the only difference when it comes to the chromosomes. Females will have two X chromosomes within their reproductive cells, while men have one X and one Y chromosome.

These can determine the sex of the offspring. For example, the women’s cell is always going to copy an X chromosome as that is all that her reproductive cells have to offer. However, the father’s cell can either copy the X or the Y chromosome.

If the offspring is made up of two X chromosomes at fertilization, the sex will be a girl. However, if the cells copied were an X and a Y the child will be a boy. Inheriting chromosomes can come at risk if the wrong number is inherited.

For example, women who inherit too many copies of the X chromosome can be taller and suffer from some mental inabilities. Males with more than one X chromosome will develop Klinefelter syndrome, a condition affecting their height and fertility.

Turner syndrome is also a possibility and this is where the person only has one X chromosome. Sufferers will often be shorter and struggle to undergo puberty. They might also suffer from heart or kidney problems.

Do all living beings have the same type of chromosomes? 

Not at all, as chromosomes vary in many different ways. Bacteria have chromosomes but these are often circular rather than linear. Humans, animals, and many plants have linear chromosomes that reside in pairs within the cell nucleus.

As we’ve mentioned before, the only human cell that doesn’t contain pairs of chromosomes is the reproductive cells. These are also called gametes, and these only carry one copy of each parent’s chromosome.

When the mother and father’s reproductive cells come together, they turn into a single cell which now contains a copy of both of their chromosomes. This cell multiplies and eventually turns into a baby with a full set of their own chromosomes.

Other than the linear chromosomes that are found in the nucleus of our cells, you can also find smaller chromosomes within cells that are not unlike that found in bacteria. These are circular chromosomes within the mitochondria of the cells, otherwise known as the cell’s powerhouse.

Scientists believe that the mitochondria were once free-living bacteria that could convert oxygen to energy. Once the bacteria invaded cells without enough power to use the oxygen’s power, the cells trapped them. Over time, the bacteria evolved into the mitochondria that we now know and love.

How were chromosomes discovered? 

From reading our article, you might be wondering to yourself how on earth chromosomes were ever found inside of our bodies. Well, scientists have been looking for solutions to all of the questions about the human body for many years, and the invention of the microscope was a big help in discovering chromosomes.

In the late 1800s, scientists observed chromosomes underneath the microscope. However, they did not have the necessary information and equipment to be able to work out the cell structures and functions yet.

Moving into the early 20th century, more developments came about and Thoman Hunt Morgan’s pioneering work helped researchers to understand chromosomes more. Morgan made a link between the inheritance of traits and chromosomes.

He did this by demonstrating that the X chromosome could determine eye color and gender. He used fruit flies as his test subjects before more people backed his research and realized that he had cracked the code to chromosomes.


We hope that you’ve learned some valuable information from our article today. There are 23 pairs of chromosomes in the human body, meaning that we have 46 chromosomes in total. Different numbers of chromosomes can lead to health problems such as Down Syndrome.

The only cells in our body that don’t have a pair of chromosomes are the reproductive cells, as these have a copy of all of our chromosomes. This is ready to merge with a partner reproductive cell and create a new human being.

This is why offspring has a mixture of traits from both the mother and the father. Men and women also have different chromosomes in the reproductive cells, which can be used to determine the sex of the offspring.

It’s not just humans that have chromosomes, as many animals and plants have their own pairs of chromosomes as well. Even things as tiny as bacteria have chromosomes, although these are not the same shape as human chromosomes.

Chromosomes were first discovered in the late 1800s and understood in the early 1900s, but scientists are still working on understanding them better today.