Which adaptations are developed by thermophiles to withstand extremely high temperature? Check all that apply.
A high proportion of unsaturated fatty acids in the cell membrane
B high cytosine-guanine nitrogenous bases
C more saturated fatty acids in cytoplasmic membrane
D heat-stable enzymes
The correct answer and explanation is :
The correct adaptations for thermophiles to withstand extremely high temperatures are:
C) More saturated fatty acids in cytoplasmic membrane
D) Heat-stable enzymes
Explanation:
Thermophiles are microorganisms that thrive in extremely hot environments, often ranging from 45°C to 80°C or higher. These organisms have evolved several adaptations to survive and function optimally in such extreme conditions. Let’s explore the correct adaptations in detail:
- More Saturated Fatty Acids in Cytoplasmic Membrane (C):
Thermophiles adapt their cell membrane composition to withstand high temperatures. One key adaptation is an increase in the proportion of saturated fatty acids in their cell membranes. Saturated fatty acids have straight chains that pack more tightly together, which increases the stability and rigidity of the membrane at high temperatures. This prevents the membrane from becoming too fluid and disintegrating under the heat, allowing the cell to maintain its integrity. - Heat-Stable Enzymes (D):
Enzymes are essential for biochemical reactions in any organism, including thermophiles. In high-temperature environments, enzymes are at risk of denaturation, where their structure unravels, causing them to lose functionality. Thermophiles have evolved enzymes that are more heat-stable, meaning they are more resistant to the denaturing effects of heat. These enzymes have structural adaptations, such as increased ionic bonds, hydrophobic interactions, and other modifications that help maintain their three-dimensional structure even at high temperatures. This ensures that the enzymes remain functional and can continue catalyzing necessary reactions.
Incorrect Options:
- A) High Proportion of Unsaturated Fatty Acids in the Cell Membrane:
Unsaturated fatty acids have one or more double bonds in their hydrocarbon chains, which introduce kinks and prevent the fatty acids from packing closely together. This increases membrane fluidity, which is beneficial in colder temperatures but detrimental in extreme heat. Therefore, thermophiles typically have fewer unsaturated fatty acids in their membranes to avoid fluidity that could disrupt membrane function at high temperatures. - B) High Cytosine-Guanine Nitrogenous Bases:
The DNA of thermophiles often contains a higher proportion of guanine (G) and cytosine (C) nitrogenous bases compared to adenine (A) and thymine (T). This is because G-C base pairs are more thermodynamically stable than A-T base pairs due to the triple hydrogen bond between G and C compared to the double bond between A and T. However, this adaptation alone does not directly protect against heat. The main structural feature responsible for the heat stability of DNA in thermophiles is the overall higher G-C content rather than just a higher proportion of nitrogenous bases.