A Guide to Sickle Cell Science

Updated: Jul 18, 2021

Written & Researched By: Riya Nalla



Have you ever wondered what makes up you as a human? Or how super small DNA can cause disorders that could last a lifetime? DNA is super crucial to the science and composition of life, and many times, it often gets altered for the worse. What do these alterations sometimes result in? Genetic disorders. These are disorders caused by changes in the DNA sequence (known as mutations) that affect different parts of our body and cause health concerns that affect people in day-to-day life like sickle cell anemia.



Mutations in the DNA Sequence


There is a wide variety of possible mutations that can happen in the DNA, actually not all being bad for the body. When we think of mutations, a zombie apocalypse or a violent disease often come to mind, but mutations are actually far from that! Plenty of mutations happen in our body that don’t actually cause any harm because sometimes, things just happen, and a few mistakes are made, just like in life! Mutations occur as the DNA translates to mRNA, which transcribes to amino acids to create proteins (this is called protein synthesis). These are really important for our bodies to stay healthy. Some different types of mutations include point mutations and frameshift mutations (all of which happen normally in DNA). These might sound super confusing, but they are actually pretty simple and comparable to daily life if you think about it!


Point mutations (these only change one base in the DNA):

  • Silent mutation: This is called silent because it doesn’t make a difference in the proteins that come out of protein synthesis! In this mutation, the mRNA transcribes to the same amino acid even with the mutation so there is really no big change. Think of this like a small mistake on a test you are taking, but it does not change the fact that you pass!

  • Missense mutation: In this one, an mRNA codon transcribes to a different amino acid than without the mutation, causing it to completely change a DNA sequence! Similarly, sometimes, a really small difference can make a huge change in our lives.

  • Nonsense mutation: This means that an mRNA codon transcribes to a stop codon instead of an amino acid. The sequence completely stops, hence the name stop!

Nonsense Mutation Example

Frameshift mutations (this changes the DNA sequence completely):

  • Insertion: This is when a base gets inserted, changing the entire DNA sequence. Think of it like a new family member being added that changes the complete family dynamic.

  • Deletion: This is when a base gets deleted, changing the entire DNA sequence! For example, a close neighbour moves out, which causes a difference in the neighbourhood.

Deletion Mutation Example

What does Sickle Cell Anemia have to do with Mutations?


Sickle Cell Anemia is a genetic disorder actually caused by a point mutation, specifically a missense mutation, in which the HBB (hemoglobin) gene turns into HbS, HbE, etc., all of which are not normal. Hemoglobin is super important because it carries oxygen around the body and is super important for our health (remember that we inhale oxygen to breathe?) Because of this, red blood cells are abnormally shaped, rather than round like regular red blood cells would be!


Sickle Cell Anemia causes a lot of pain because the sickle cells can get stuck in blood vessels, and since the cells do not grow properly, it also causes difficulty in the organ system.



Hemogoblin Gene Examples

Sources

(plus learn more about sickle cell anemia and mutations in genetic disorders here):

https://medlineplus.gov/genetics/condition/sickle-cell-disease/#frequency https://www.healthgrades.com/right-care/heart-health/which-type-of-mutation-causes-sickle-cell-anemia

https://www.cdc.gov/ncbddd/sicklecell/facts.html

https://courses.lumenlearning.com/microbiology/chapter/mutations/

30 views0 comments

Recent Posts

See All