What is Condensation?
Condensation is the conversion of water from its gaseous form (water vapor) into liquid water. Condensation generally occurs in the atmosphere when warm air rises, cools and loses its ability to hold water vapor.
As a result, excess water vapor condenses to form cloud droplets. The upward movements that clouds create can be created by convection in unstable air, convergence associated with cyclones, lifting of air by fronts, and lifting above an elevated topography such as mountains.
Condensation has several meanings in the field of biology. A condensation reaction is when two smaller molecules combine to form a larger one by removing functional groups that make up a small molecule, often water.
Condensation can also refer to a change in the state of water from gas to liquid, which is an important step in the water cycle. There is also DNA condensation, in which chains of deoxyribonucleic acid (DNA) condense into a denser structure as a cell prepares to divide.
Condensation Reactions in biology
A condensation reaction is the formation of a larger molecule from two smaller ones that also form another, smaller molecule by losing functional groups in order to combine with each other.
Some examples of small molecules that are byproducts of condensation reactions are acetic acid (CH3COOH) and methanol (CH3OH), but most of the time water (H2O) is formed from one molecule that is losing hydrogen (H) and another that has a hydroxyl group (-OH) mainly loses out on the biological reactions that take place in living things. When water is a product, the condensation reaction is often referred to as the dehydration reaction.
Condensation reactions are used to make important large molecules called macromolecules in the body, such as carbohydrates, lipids, and proteins. Carbohydrates are simple sugars like glucose that are used for energy in the body.
A sugar with a ring is a monosaccharide, and condensation reactions combine glucose units into disaccharides, which also creates water. When more than two sugars are linked, the molecule is called a polysaccharide.
Glucose is stored in long chains that are made through many dehydration reactions, and this molecule is called glycogen. When more energy is needed in the body, glucose is a necessary component, and glucose molecules are then broken off the chain through hydrolysis, adding water (and the opposite of dehydration reactions).
Similarly, glycerol and three fatty acids are linked together through condensation reactions to form a lipid molecule, and amino acids are linked to form proteins. In the body, lipids are fats and certain vitamins and they have many functions such as energy storage, cell signaling, and the formation of the lipid bilayer of the cell membrane.
Proteins support the occurrence of certain chemical reactions and also play a role in the transmission of signals from cells and the structuring of body parts. For example, the proteins collagen and elastin are found in cartilage. Without condensation reactions, not all of these important molecules could be formed.
Examples of Condensation
Condensation in the Water Cycle
Condensation is part of the water cycle, which describes how water flows continuously over the earth in solid, liquid, and gaseous forms. During condensation, the water vapor in the air changes from gas to liquid water. As altitude increases, both temperature and water pressure decrease, turning water vapor into liquid water.
A very large concentration of these water droplets forms clouds and fog. The water then falls as precipitation on the earth’s surface. It falls back into the earth’s waterways and also ends up in the soil where it can be ingested by plants. Water can also freeze into its solid form, ice, and then melt again in the water.
This can appear as snow or on the surface of the earth where temperatures are below freezing. Next, evapotranspiration occurs and the water changes from liquid form to gaseous form. Evapotranspiration is the combination of evaporation from the oceans, lakes, and rivers of the earth and transpiration when excess water evaporates from plants.
Evapotranspiration allows water to get back into the air and the water cycle starts all over again. The water cycle is vital in all of the earth’s ecosystems, as all living things need water to survive.
DNA condensation occurs in all organisms. Unlike the other forms of condensation mentioned in this article, this condensation is not water. It’s about getting the DNA into a smaller space. In eukaryotes, which includes all living things that are not archaea or bacteria, DNA condensation occurs during mitosis, the process of cell division.
During the prophase stage of mitosis, strands of DNA condense into nucleosomes, which are segments of DNA wrapped around histone proteins. DNA wrapped around proteins is called chromatin. The nucleosomes then fold even more to form chromosomes. DNA is always folded to some extent; If all of the DNA were stretched out in one of your cells, it would be 2 meters long!
Bacterial DNA forms a circular, continuous loop. In order for all of the DNA of a bacterium to fit in, the DNA strands have to be made about 1000 times smaller. Instead of histone proteins in eukaryotic cells, DNA binding proteins are used to form loops within the circular chromosome to condense it. Then these loops spin on themselves to further condense the DNA in a process known as supercoiling.
Even viruses that are not considered true living things because they cannot multiply without invading a cell have DNA that condenses. The DNA needs to be condensed because it is longer than the virus’ capsid, which is the protein envelope that contains the DNA. The DNA is essentially wound like a coil in the capsid by a powerful motor that can condense the DNA very tightly.