BIOLOGY

  Peptide bonds are unusually stable when compared to other linkages. Justify with a neat diagram. answer: Why peptide bond is stronger  1. Peptide bonds are strong with partial double bond character: They are not broken by heating or high salt concentration. They can be broken by exposing them to strong acid or base for a long time at elevated temperature. Also by some specific enzymes (digestive enzymes). 2. Peptide bonds are rigid and planar bonds therefore they stabilize protein structure. 3. Peptide bond contains partial positive charge groups (polar hydrogen atoms of amino groups) and partial negative charge groups (polar oxygen atoms of carboxyl groups). Peptide Bond Formation or Synthesis A peptide bond is formed by a  dehydration synthesis  or reaction at a molecular level.  This reaction is also known as a condensation reaction which usually occurs between amino acids. As depicted in the figure given below, two amino acids bond together to form a ...

  10.Many cellular proteins do not have structures that noticeably correlate with their functions. Explain. answer: Intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs) are functional proteins or regions that do not have unique 3D structures under functional conditions. Therefore, from the viewpoint of their lack of stable 3D structure, IDPs/IDPRs are inherently unstable. As much as structure and function of normal ordered globular proteins are determined by their amino acid sequences, the lack of unique 3D structure in IDPs/IDPRs and their disorder-based functionality are also encoded in the amino acid sequences. Because of their specific sequence features and distinctive conformational behavior, these intrinsically unstable proteins or regions have several applications in biotechnology. This review introduces some of the most characteristic features of IDPs/IDPRs (such as peculiarities of amino acid sequences of these proteins and regions,...

  8.Illustrate the tertiary structure of a ribozyme with a note about their function in therapeutics.  ANSWER: Ribozymes: structure, function, and potential therapy for dominant genetic disorders Some dominant genetic disorders, viral processes and neoplastic disorders base their pathogenicity on the production of protein or proteins that negatively affect cellular metabolism or environment. Thus, the inhibition of the synthesis of those proteins should prevent the biological damage. A promising approach to decreasing the level of the abnormal protein(s) is represented by specific interference with gene expression at the level of mRNA. The specific suppression of the expression of an mRNA can be achieved by using ribozymes. Ribozymes are RNA molecules able to break and form covalent bonds within a nucleic acid molecule. These molecules, with even greater potential advantages than antisense oligodeoxynucleotides, are able to bind specifically and cleave an mRNA substrate. There...

  6.Illustrate the double helix of DNA with details about base pairing, strand polarity, and physical dimensions. answer: polarity Antiparallel - Direction and Polarity in DNA DNA is Antiparallel That DNA is antiparallel means that the two strands of DNA have opposite chemical polarity, or, stated another way, their sugar-phosphate backbones run in opposite directions. Direction in nucleic acids is specified by referring to the carbons of the ribose ring in the sugar-phosphate backbone of DNA. 5' specifies the the 5th carbon in the ribose ring, counting clockwise from the oxygen molecule, and 3' specifies the 3rd carbon in the ring. Direction of, and in reference to, DNA molecules is then specified relative to these carbons. For example, transcription, the act of transcribing DNA to RNA for eventual expression, always occurs in the 5' to 3' direction. Nucleic acid polymerization cannot occur in the opposite direction, 3' to 5', because of the difference in chemi...

  5.Illustrate the condensation reaction that is responsible for the backbone structure  of nucleic acids. answer: condensation reaction means the removal of water molecules and form the bond. Hint:- Deoxyribonucleic acid is a double helix structure composed of two polynucleotide chains that coil around each other to form a genetic molecule carrying genetic instructions for the growth, development and reproduction of organisms. The two strands of DNA chain run in opposite directions to each other and are thus called antiparallel. Complete Answer:- DNA is a heteropolymer of deoxyribonucleotides, which are made up of a pentose sugar, nitrogenous bases and a phosphate moiety. Each nucleotide is composed of one of the four nitrogen molecules containing nucleobases (cytosine, guanine, adenine or thymine), a deoxyribose sugar and a phosphate group. Two successive nucleotides are joined by covalent bonds called phosphodiester bonds present between the sugar of one nucleotide and phos...

  4.Cholesterol and phospholipids are both amphipathic lipids that do not dissolve in water. Justify. answer: Hint:  Amphipathic molecules are also known as amphiphilic molecules. Cholesterol, detergents, and phospholipids are an example of amphipathic molecules. Complete Answer: - The chemical compounds which have at least one hydrophilic portion and one hydrophobic portion are called amphipathic molecules. They contain properties of both types. - Most membrane lipids are amphipathic. The typical example is phospholipids found in the cell membrane. The hydrophilic region is also called the water-loving head and face outside. On the contrary, the hydrophobic region also called water-repelling ends has two tails of fatty acids. - Hydrophobic tails usually face towards the center of the membrane. This makes the cell membrane a lipid bilayer. Another example is soap, which has a hydrophilic head and a hydrophobic tail, allowing it to dissolve in both water and oil. Cholesterol is...

  3.Bond saturation profoundly affects the state of lipids  with an impact on cardiovascular health. Justify. answer: How Saturated Fats Affect Your Health Saturated fats are bad for your health in several ways: Heart disease risk.  Your body needs healthy fats for energy and other functions. But too much saturated fat can cause  cholesterol  to build up in your arteries (blood vessels). Saturated fats raise your LDL (bad) cholesterol. High LDL cholesterol increases your risk for heart disease and stroke. extra : What are saturated fats? Saturated fats are typically solid at room temperature. How do saturated fats affect my health? Saturated fats are found in animal-based foods like beef, pork, poultry, full-fat dairy products and eggs and tropical oils like coconut, and palm. Because they are typically solid at room temperature, they are sometimes called “solid fats.” Saturated fats can cause problems with your cholesterol levels, which can increase your risk o...

  2.Compare the functions of starch and glycogen with a note about their different linkages. answers:  Difference between Starch, and Glycogen The table below shows the main differences between starch, cellulose and glycogen. Starch Glycogen It is a polymer of 𝜶-glucose subunits It is a polymer of 𝜶-glucose subunits It contains two types of polymers, amylose (unbranched and coiled) and amylopectin (branched) It is highly branched and similar to amylopectin The 𝜶-glucose subunits are joined by 1,4 glycosidic bonds in amylose and 1,4 and 1,6 glycosidic bonds in amylopectin The 𝜶-glucose subunits are joined by 1,4 and 1,6 glycosidic bonds Amylose is unbranched and amylopectin is branched It is highly branched It is the main storage carbohydrate in plants It is the main storage carbohydrate in animals and fungi Structure of Starch Starch is the main storage carbohydrate of plants. It is made up of 𝜶-glucose subunits. It contains two types of polymers, amylose and amylopectin....

  11.Explain the relationship between electron transport and oxidative phosphorylation. What does ATP synthase look like, and how does it work? answer:  How is electron transport couple to oxidative phosphorylation? Reactions of the electron transport chain take place in the inner mitochondria membrane, and production of ATP in the mitochondria comes from oxidative phosphorylation [ADP is phosphorylated to give ATP] Proton gradient is created by the pumping of electrons and represents stored potential energy, and provides basis for a coupling mechanism.      “Oxidative phosphorylation is the process of ATP formation, when electrons are transferred by electron carriers from NADH or FADH2 to oxygen” What is Oxidative Phosphorylation? Oxidative phosphorylation is the final step in cellular respiration. It occurs in the mitochondria. It is linked to a process known as electron transport chain. The electron transport system is located in the inner mitochondrial membr...

  9. Discuss the discovery of ATP synthase complex and its role in high-energy molecule production. answers:  ATP SYNTHASE PATHWAY DISCOVERY:  In 1997 the Nobel Prize in chemistry was awarded to Professor Paul D. Boyer, University of California, Los Angeles, USA, and Dr. John E. Walker, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom for their elucidation of the mechanism of ATP synthase. With Dr. Nicholson and the IUBMB, we are proud to begin our metabolic pathways animation series with an interpretation of the ATP synthase molecular machine. Electron transport chain: Electron Transport Chain is a series of compounds where it makes use of electrons from electron carriers to develop a chemical gradient. It could be used to power oxidative phosphorylation. The molecules present in the chain comprise enzymes that are protein complex or proteins, peptides, and much more . ATP synthase is the complex V of the electron transport chain. It ca...

23.    Defend the central dogma of molecular biology against some of the exceptions to it.  answer: Why are RNA viruses exceptions to the central dogma? Solution Central dogma: The process in which information in DNA is converted into a product. In this process, protein is made from DNA molecules. In central dogma, DNA undergoes transcription to form RNA which then undergoes translation to form proteins. In this process, genetic information is transferred in a single direction from DNA to RNA, RNA to proteins, or RNA directly to protein. RNA viruses or retroviruses are exceptions to central dogma because retroviruses form RNA from DNA by the process of reverse transcription. Since RNA viruses do not follow this unidirectional flow of information thus, they are exceptions to central dogma.

  24. Defend Gamow’s hypothesis about the genetic code with some of its salient features. answers: (i) George Gamow suggested that the genetic code should be made up of a combination of three nucleotides. (ii) He proposed that if 20 amino acids are to be coded by 4 bases, then the code should be made up of three nucleotides. 4 3  = 64 (4 2  = 16), which is less than 20. So, the codon was proposed to be triplet. Characteristics of the Genetic Code The genetic code has a number of important characteristics. The genetic code is universal. All known living organisms use the same genetic code. This shows that all organisms share a common evolutionary history. The genetic code is unambiguous. Each codon codes for just one amino acid (or start or stop). What might happen if codons encoded more than one amino acid? The genetic code is redundant. Most amino acids are encoded by more than one codon. In  Figure   above , how many codons code for the amino acid threonine? W...

  21.Propose the chemiosmosis hypothesis with a note on oxidative phosphorylation in mitochondria. anjswer: Hint:  The hydrogen ion gradient produced by the electron transfer chain is utilized by ATP synthase to produce ATP in oxidative phosphorylation. The changing of this molecular system controls the potential energy kept in the hydrogen ion gradient to add up a phosphate to ADP, forming ATP. Complete Answer: ATP synthesis associated with the transport of electrons from the inner membrane region via the innermost membrane, back to the matrix. The transport of electrons from the matrix to the inner membrane region causes a considerable pH difference between the two parts of the membrane. Mitchell recognized that this represents a large energy difference, because the chemiosmotic potential is actually composed of two components.  Now, let us find the solution from the option. - Phosphorylation is a biochemical process that involves the addition of phosphate to an organic...