February 26, 2025
A Level Biology Revision (Year 13)

A Level Biology Revision (Year 13) “Tumour Suppressor Genes and Abnormal DNA methylation”

Author: Freesciencelessons via YouTube
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A Level Biology Revision (Year 13)

In this video, we look at tumour suppressor genes and abnormal DNA methylation in the development of cancer. First we look at what is meant by a tumour suppressor gene. We then look at the functions of tumour suppressor genes including DNA repair and programmed cell death (apoptosis). We look at the examples of BRCA1/BRCA2 and TP53. We then explore how hypermethylation of tumour suppressor genes or hypomethylation of oncogenes increase the risk of developing cancer.

Image credits:

Malignant melanoma scalp
https://commons.wikimedia.org/wiki/File:Malignant_Melanoma_Mid_Frontal_Scalp.jpg
Dermanonymous, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Fibroma
https://commons.wikimedia.org/wiki/File:Fibroma.jpg
Klaus D. Peter, Wiehl, Germany, CC BY 3.0 DE https://creativecommons.org/licenses/by/3.0/de/deed.en, via Wikimedia Commons

Breast cancer mammogram
https://commons.wikimedia.org/wiki/File:Mammo_breast_cancer.jpg
This work is in the public domain in the United States because it is a work prepared by an officer or employee of the United States Government

Colorectal cancer (modified by S. Donnelly)
https://commons.wikimedia.org/wiki/File:Pre_and_post_chemotherapy_colorectal_cancer.png
KIICHI SUGIMOTO, KAZUHIRO SAKAMOTO, CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons

Lung cancer
https://commons.wikimedia.org/wiki/File:LungCACXR.PNG
James Heilman, MD, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Cell undergoing apoptosis
https://commons.wikimedia.org/wiki/File:HeLa-IV.jpg
National Institutes of Health (NIH), Public domain, via Wikimedia Commons

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