The amino acids glutamine and glutamic acid are shown in Figure Q1. They differ

Question

The amino acids glutamine and glutamic acid are shown in Figure Q1. They differ only in the structure of their side chains (circled). A pH 7, glutamic acid can participate in molecular interactions that are not possible for glutamine. What types of interactions are these? The cell is able to harvest energy from various processes in order to generate ATP molecules. These ATPs represent a form of stored energy that can be used later to drive important processes. Explain how the cell can convert the chemical energy stored in ATP to generate mechanical energy, for example changing the shape of a protein. As a protein is made, the polypeptide is in an extended conformation, with every amino acid exposed to the aqueous environment. Although both polar and charged side chains can mix readily with water, this is not the case for nonpolar side chains. Explain how hydrophobic interactions may play a role in the early stages of protein folding, and have an influence on the final protein conformation. Eukaryotic cells have their DNA molecules inside their nuclei. However, to package all the DNA into such a small volume requires the cell to use specialized proteins called histones. Histones have amino acid sequences enriched for lysines and arginines. A. What problem might a cell face in trying to package DNA into a small volume without histones, and how do these special packaging proteins alleviate the problem? B. Lysine side chains are substrates for enzymes called ac A diagram of an acetylated lysine side chain is shown in Figure Q4. How do you think the acetylation of lysines in histone proteins will affect the ability of a histone to perform its role (refer to your answer in part A)?

Explanation / Answer

Q1. At pH 7 glutamic acid has a negative charge (as depicted in the figure). So they can take part in the ionic interactions at this pH. whereas, glutamine has a neutral charge at pH 7, so it won't be able to take part in the ionic interactions at this pH. The interaction type is ionic interactions.

Q2. Hydrolysis of ATP into ADP and inorganic pyrophosphate changes the chemical energy to the mechanical energy. Kinesin is a protein that has a binding site for ATP. after ATP binding the hydrolysis of ATP causes the structure of this protein to change. This structural change helps in the motion of kinesin. In this process, the chemical energy stored in the ATP helps to drive a mechanical process.

Q3. Hydrophobic interactions help proteins to achieve the compact nonpolar core structure. Due to this hydrophobic core of the protein gets its compact three-dimensional structure.

Q4. A. In absence of histones the length of the DNA will be very large and packing this DNA in the small volume of the cell will be really impossible. for example, the human diploid cell contains DNA that has a length of approximately 1.8 meters. When this DNA gets wind around the histones it becomes 90 micrometers. Histones are positively charged and so they bind very tightly to the negatively charged DNA,

B. Acetylation of lysine residues in histones will neutralize the positive charge. This histone acetylation will affect its interactions with DNA, loosening the DNA wrapping around the histones. Highly acetylated histones form loose chromatin structure.

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