Introduction:
How do different species survive intense weather temperatures – like the freezing temperature of Antarctica? These phenomena of living through harsh conditions and thriving are done through adaptations - caused by mutations in the body.
Mutation To Adaptation:
Mutations, simply put, are when our DNA sequence changes (primarily caused by DNA not being copied correctly or the DNA strand(s) breaking). The mutation could have occurred because of deletion, parts of DNA being deleted; duplication, parts of DNA being duplicated; inversion, segment breaks, reverses, and attaches to the same chromosome; translocation, DNA from one chromosome breaks off and attaches to the end of sister chromosome; or something entirely different. Suppose the DNA glycosylases (the DNA repair enzymes) can’t find the mistake when they’re sweeping through the DNA strand. In that case, it goes through the process of transcription - where an mRNA strand is created through reading the DNA: the best way to recognize mRNA is through the presence of U (Uranine) that replaces the T (Thymine); Afterwards, the mRNA goes into the ribosome and it’s information gets ‘translated’ into amino acids. These acids continue to form chains (polypeptides) until they receive a ‘stop’ signal from the mRNA. Once there are enough polypeptides, they coil up together in special orders (depending on the certain restrictions of that specific polypeptide) to form several proteins. Proteins do most of the work in our body by regulating the structure and function of our body’s organs and tissue. A change in DNA directly affects our protein – this could therefore cause no harm, be harmful (harms the organism's chance of survival) or even beneficial improves the organism's chance of survival) to the organism’s body. If the change in protein is positive then it is considered an adaptation. These adaptations allow organisms to face drastic changes in their environments, whether it be the introduction of a new species or harsh weather.
Purpose And Definition of AntiFreeze Proteins:
To survive cold climates where the temperature dips below freezing, and ice begins forming (water freezes and continues to expand) inside an organism’s cells, causing the cell to burst over time as the ice crystal grows. To prevent the growth of ice crystals, several organisms have developed an in-built adaptation of lining compounds similar to sugars and glycerol (naturally occurring alcohol used in every-day soap) around their cells to diminish the ice. When the cell needs extra ‘layers of protection’, the second safety adaptation kicks in to protect the cell from the cold, which is the making of antifreeze proteins. Antifreeze proteins are meant to limit the growth of ice crystals, making the cold manageable. They do so by latching onto the ice particles which prevents the water around from freezing.
Properties of AntiFreeze proteins:
Antifreeze proteins are a well-fitted adaptation as they bring along several properties that aid the organism in eliminating ice crystals and heating up. Two of the most significant properties are ice restructuring and supercooling.
Property # 1 (Ice Restructuring):
Because antifreeze proteins, also known as ice-restructuring proteins, bind onto the place where ice and water - coexist ( and is the most common location for ice seeds to form and grow into ice crystals ), they diminish the quirk that normally comes with ice: recrystallization. Recrystallization is the process of small ice crystals being formed from water freezing which then dominate and grow in the cell that ruptures the cell. By latching onto the ice seed, antifreeze proteins ensure that the small crystals remain as they are, small. They can also be placed outside the cell as ‘guards’ to ensure that a non-controllable ice crystal does not destroy the cell.
Property # 2 (Super Cooling):
Antifreeze proteins can scale down the freezing point of water without changing the melting point. This is considered super cooling as the liquid stays in form while the temperature is much below freezing point. The thermal hysteresis ( difference between the original and changed freezing point ) can be as much as 6 degrees for insects, while a lot less for plants and bacteria.
Conclusion:
An adaptation that allows organisms to survive the coldest of weather, antifreeze proteins are being tested on, and used for surplus items. They are now commonly being used to maintain the texture and temperature of ice cream and have the potential to do a lot more with the help of their properties and relation with ice. Now, it’s only a matter of time till antifreeze proteins are better understood and one can see their full potential unlocked.
Reference:
“Home.” Understanding Evolution, evolution.berkeley.edu/evolution-101/mechanisms-the-processes-of-evolution/the-causes-of-mutations/. Accessed 1 Feb. 2025.
Kuiper, Michael J, et al. “The Biological Function of an Insect Antifreeze Protein Simulated by Molecular Dynamics.” eLife, U.S. National Library of Medicine, 7 May 2015, pmc.ncbi.nlm.nih.gov/articles/PMC4442126/#:~:text=Antifreeze%20proteins%20(AFPs)%20protect%20certain,crystals%20and%20inhibiting%20ice%20propagation.
Muñoz, Patricio A., et al. “Structure and Application of Antifreeze Proteins from Antarctic Bacteria - Microbial Cell Factories.” BioMed Central, BioMed Central, 7 Aug. 2017, microbialcellfactories.biomedcentral.com/articles/10.1186/s12934-017-0737-2.
Nature News, Nature Publishing Group, www.nature.com/scitable/topicpage/translation-dna-to-mrna-to-protein-393/. Accessed 1 Feb. 2025.
“PDB101: Molecule of the Month: Antifreeze Proteins.” RCSB, pdb101.rcsb.org/motm/120. Accessed 1 Feb. 2025.
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