> For the complete documentation index, see [llms.txt](https://helyx.gitbook.io/geneexpression/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://helyx.gitbook.io/geneexpression/crash-course-biology.md).

# Background Knowledge

To understand this course, you should be familiar with:

1. What a microarray is and what it does
2. What is gene expression?

Essentially microarrays are cool devices that let us measure how much each gene is "expressed" in a given sample, such as a patient's cells.

For example, let's say there's a gene called ABCD. Hypothetically, ABCD is "expressed" as a protein that leads to cancer somehow. We'd expect ABCD to be more "expressed" in people with cancer.

We can use a microarray to confirm our hypothesis by measuring how much ABCD expression there is in cancer patients vs. non-cancer people.

What exactly is gene expression? Gene expression is how much a gene is expressed. Genes are expressed when they are transcribed to RNA and then made into protein. Microarrays can measure the amounts of RNA for each gene and from that information, you can infer how much the gene is expressed.

![Gene Expression flowchart. Credit: https://www.azolifesciences.com/article/A-Guide-to-Understanding-Gene-Expression.aspx](/files/-M_YAd2UX8FIX0mGIaEO)

Don't understand this explanation? Check out the free recommended resources below. 

{% hint style="info" %}
Please review the following resources if you are unfamiliar with the central dogma and biotechnology. Credit to the original creators!
{% endhint %}

{% embed url="<https://www.yourgenome.org/facts/what-is-the-central-dogma#:~:text=The%20'Central%20Dogma'%20is%20the,of%20the%20structure%20of%20DNA>." %}

{% embed url="<https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_Introductory_Biology_(CK-12)/04%3A_Molecular_Biology/4.01%3A_Central_Dogma_of_Molecular_Biology>" %}

{% embed url="<https://bitesizebio.com/7206/introduction-to-dna-microarrays/>" %}

{% embed url="<https://learn.genetics.utah.edu/content/labs/microarray/>" %}

{% embed url="<https://www.youtube.com/watch?v=Hv5flUOsE0s>" %}


---

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