Biological Molecules Session IV

Did you know that tiny sulfur atoms can form bonds that hold together the complex structures of proteins? These bonds are called disulfide linkages. They are like the tiny glue that holds together the intricate folds and twists of protein molecules. As we know, proteins are made up of long chains of amino acids. Cysteine is one of the 20 different types of amino acids that make up proteins. Disulfide linkage refers to a covalent bond between two sulfur atoms. Each sulfur atom is also bonded to a carbon atom or a nitrogen atom.

Disulfide linkage is formed by the oxidation of two thiol -SH groups in cysteine amino acids. This results in the formation of a disulfide bridge -S-S-. The disulfide bond is a strong and stable covalent bond that can withstand harsh conditions such as heat and pH extremes. Disulfide bonds have a crucial role in stabilizing the tertiary and quaternary structures of proteins.

As we know , ionic bonding is a type of chemical bond that involves the transferring of electrons from one atom to another. In proteins, ionic bonds can form between amino acids that have charged side chains. These amino acids are arginine which is positively charged and aspartic acid which is negatively charged. These charged amino acids can interact with each other to form a salt bridge. A Salt Bridge is an ionic interaction between oppositely charged amino acid side chains.

Have you ever wondered how our blood carries oxygen? Hemoglobin is a protein in blood that carries oxygen. Hemoglobin is an example of globular protein. Globular proteins are a type of protein that has a roughly spherical shape. They have compact and folded structure. They are soluble in water. This is because globular proteins are polar and water is also polar. Globular proteins are typically found in the cytoplasm or extracellular fluid of cells.

The structure of globular protein includes a core made up of hydrophobic amino acids. Hydrophobic means, water repelling. This core is surrounded by hydrophilic amino acids on the protein's surface. Hydrophilic means, water attracting. The hydrophobic core of the protein provides a binding site for specific molecules. The hydrophilic surface of the protein allows it to interact with the surrounding environment.

We know that hemoglobin is a globular protein. It is composed of four subunits. Each subunit of hemoglobin consists of a long chain of amino acids that folds into a unique three dimensional shape. Each subunit contains a heme group. The heme group is located at the center of each subunit of hemoglobin. It consists of a flat, planar molecule called porphyrin, which is bound to an iron atom. Heme group is responsible for binding oxygen.

Oxygen molecules bind to the iron atoms in the heme group, The shape of the protein changes slightly upon oxygen binding. This structural change makes it easier for the other three subunits of hemoglobin to bind oxygen molecules as well. This leads to the cooperative binding of oxygen.

In addition to oxygen, hemoglobin can also bind to carbon dioxide. When carbon dioxide is produced by the tissues of body, it diffuses into the red blood cells and reacts with water to form bicarbonate ions. Hemoglobin can also bind to these bicarbonate ions. This allows hemoglobin to in transporting carbon dioxide from the tissues to the lungs. Carbon dioxide is released from lungs into the air during exhalation.

Now lets discuss fibrous proteins. Fibrous proteins are a type of protein that have an elongated and fibrous shape. They have repeating sequences of amino acids. This allows them to form long, linear structures that are ideal for providing support and strength to tissues.

One of the most well known types of fibrous protein is collagen. Collagen is the most abundant protein in the body. Collagen is found in connective tissues such as tendons, ligaments, and cartilage. Collagen is composed of three long polypeptide chains that are twisted together in a helical structure, forming a triple helix. Collagen provides structural support. It promotes the healing of wounds. It protects organs and helps maintain skin elasticity.

In biological systems, water acts as a solvent. This means that it is able to dissolve many different types of molecules. As we have already discussed that globular proteins are polar. They are soluble in water. This is because water is also polar. Polarity of water is due to partial positive charge on one end and a partial negative charge on the other end. Because of its polarity, water can dissolve polar molecules such as sugars, amino acids, and nucleic acids.

Have you ever wondered why water is such an amazing substance that has a crucial role in our lives? One of the fascinating properties of water is its specific heat capacity. It's like a superpower that makes water an excellent temperature regulator. Specific heat capacity is the amount of energy required to raise the temperature of a substance by one Celsius. Water can absorb and store a large amount of heat energy without changing its temperature much.

Water has very high specific heat capacity. This is because of its ability to form hydrogen bonds with other water molecules. The specific heat capacity of water is approximately four point one eight four Joules per gram per Celsius. This value is valid at a pressure of one atmosphere and within a temperature range of zero Celsius to hundred Celsius. This means that it takes four point one eight four Joules of energy to raise the temperature of one gram of water by one Celsius.

Did you know that water has a secret weapon that helps it change from a liquid to a gas? It's called the latent heat of vaporization. Latent heat of vaporization is the amount of heat energy required to convert one unit of liquid water into water vapor, without changing its temperature. In other words, it is the energy required to turn liquid water into steam. Water has one of the highest latent heats of vaporization of any known substance on Earth! This means that it takes a tremendous amount of energy to turn water into steam.

The latent heat of vaporization of water is approximately forty point seven kilo joule per mole. This value applies at a pressure of one atmosphere and a temperature of one hundred Celsius. This means that It takes forty point seven kilo joule per mole of energy to convert one mole of liquid water into water vapor at its boiling point. This conversion occurs without changing the temperature of the water.

Water is not only a substance that we use every day for drinking, cleaning, and cooking. It is also a powerful reagent that is used in many chemical reactions. One of the most fascinating aspects of water as a reagent is its ability to act as a catalyst. A catalyst is a substance that speeds up a chemical reaction without getting consumed in the process. Water can act as a catalyst in many chemical reactions. It helps to speed up the rate of reaction and makes it more efficient.