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The human cell

Dr Gavin Turbett, human cell, chromosome, nucleus, DNA, parents.
So cells are the basic building blocks of all living things, including the human body and our bodies are actually composed of trillions of cells. Many of them have very specialist functions. So as, for example, there are muscle cells and skin cells. There are blood cells, nerve cells and cells provide structure for the body. They take in nutrients from the food we eat. They convert those nutrients into energy and carry out various specialized functions. Very importantly, cells contain the hereditary material and can make copies of themselves and that hereditary material is DNA Deoxyribonucleic Acid.
Here is a diagram of a cell with the main parts of the cell labelled, and the part that is of most interest to us is the nucleus and this is where the the DNA itself is actually located. A useful analogy is to think of the cells of our body as being like little tiny eggs. There is the yolk of the egg and the white of the egg and they correspond to the main parts of the cell. So, we can see here that the nucleus of the cell of a human body is equivalent to the yolk of the egg whereas the cytoplasm of the cell that is equivalent to the egg white.
The DNA that is contained within the nucleus is packaged up into structures that are known as Chromosomes. Humans have twenty three pairs of chromosomes and of each pair we get one from each of our parents. And twenty two of those pairs of chromosomes are the same for everybody, irrespective of whether you’re male or female. So as, for example, we have two copies of chromosome 1, two copies of chromosome 2 and so on. The last pair of chromosomes, the 23rd pair, they are known as the sex chromosomes, and they specify your biological gender. Females have two X chromosomes and males have one X chromosome and one Y chromosome.
If the chromosome was unwound and you would then see that the DNA itself is like a very long, double-stranded molecule and a good analogy is to think of this DNA as being like a ladder. The the sides of the ladder are the structure of the ladder, but it’s the rungs of the ladder, they are the basis of DNA and this is where the information is coded. So, there are four bases Adenine, Cytosine, Guanine and Thymine and these are typically just referred to as A,C, G and T and you can see that in the diagram there and they pair up against each other, forming the rungs of the ladder.
It’s possible to sequence DNA. When they talk about sequencing DNA, they’re actually working out the order of those different bases and the code that sequence of bases is the actual information code that is required to make a human being and it’s the sequence that can subtly vary between people either as small changes or small insertions or deletions.

What are the different components of the human cell? Where is DNA found within the cell? What is the structure of DNA? In this video, let us delve into the basics of the human cell and DNA with Dr Gavin Turbett.

*References for images

Certain images in this video are sourced from here and here.

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