What do you understand by immune trafficking?

1. (a) What do you understand by immune trafficking? Immune trafficking refers to the dynamic movement of immune cells throughout the body, enabling them to survey tissues for pathogens or damage and mount appropriate immune responses. This process involves cells migrating from primary lymphoid organs (where they mature) to secondary lymphoid organs (where they encounter antigens) and then to sites of infection or inflammation. 1. (b) Write notes on cytoskeleton. The cytoskeleton is a complex network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence. It is composed of three main types of protein filaments: microfilaments (actin filaments), intermediate filaments, and microtubules. The cytoskeleton plays crucial roles in cell division, cell motility, intracellular transport, and maintaining cell shape and mechanical integrity. 2. (a) Discuss the followings: Peptidoglycans Peptidoglycans, also known as murein, are a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, forming the cell wall. This structure provides structural support and protection to the bacterial cell. It is composed of alternating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) cross-linked by short peptide chains. 2. (b) Discuss the followings: Tubulins Tubulins are a family of globular proteins that are the primary constituents of microtubules. There are several types of tubulin, with -tubulin and -tubulin being the most common, which heterodimerize to form the building blocks of microtubules. Microtubules are dynamic cylindrical polymers that play essential roles in maintaining cell shape, intracellular transport, cell motility (cilia and flagella), and chromosome segregation during cell division. 2. (c) Discuss the followings: Glycoproteins Glycoproteins are proteins that have oligosaccharide chains (glycans) covalently attached to their polypeptide side chains. The carbohydrate portion can vary greatly in size and complexity. Glycoproteins are abundant on the cell surface and in the extracellular matrix, where they play critical roles in cell-cell recognition, cell adhesion, immune responses, and as receptors for hormones and neurotransmitters. 3. (a) What do you understand by viral pathogenesis? Viral pathogenesis refers to the process by which a virus causes disease in its host. It encompasses the mechanisms by which viruses enter the host, replicate, spread within the host, evade host defenses, and ultimately cause cellular damage or dysfunction leading to the clinical manifestations of disease. Factors like viral tropism, host immune response, and viral load all contribute to pathogenesis. 3. (b) Discuss the mechanism of infection of the human immunodeficiency virus. The Human Immunodeficiency Virus (HIV) primarily infects CD4+ T cells, macrophages, and dendritic cells. The infection mechanism involves several key steps: 1. Attachment and Entry: The viral envelope glycoprotein gp120 binds to the CD4 receptor on the host cell surface. This binding induces a conformational change in gp120, allowing it to bind to a co-receptor (CCR5 or CXCR4). This secondary binding facilitates the fusion of the viral envelope with the host cell membrane, releasing the viral core into the cytoplasm. 2. Reverse Transcription: Inside the cell, the viral enzyme reverse transcriptase converts the single-stranded RNA genome into a double-stranded DNA copy. 3. Integration: The viral DNA is then transported to the nucleus and integrated into the host cell's genome by the viral enzyme integrase, forming a provirus. 4. Replication and Assembly: The provirus uses the host cell's machinery to transcribe viral RNA and synthesize viral proteins. New viral RNA genomes and proteins assemble near the cell membrane. 5. Budding and Maturation: New virions bud off from the host cell membrane, acquiring an envelope. The viral enzyme protease then cleaves precursor proteins into functional viral proteins, leading to the maturation of infectious viral particles. 4. (a) i. Define the term Glycosylation Glycosylation is the enzymatic process of adding glycans (carbohydrate chains) to proteins, lipids, or other organic molecules. This modification is one of the most common post-translational modifications of proteins and plays a crucial role in protein folding, stability, and function. 4. (a) ii. Explain the mechanisms involved in glycosylation. There are two primary mechanisms of protein glycosylation: • N-linked glycosylation: This occurs in the endoplasmic reticulum (ER) and involves the attachment of a pre-formed oligosaccharide chain to the nitrogen atom of the asparagine (Asn) residue within the consensus sequence Asn-X-Ser/Thr (where X is any amino acid except proline). The oligosaccharide is transferred from a lipid carrier molecule (dolichol phosphate) to the nascent protein. • O-linked glycosylation: This occurs primarily in the Golgi apparatus and involves the sequential addition of single sugar residues directly to the oxygen atom of the hydroxyl group of serine (Ser) or threonine (Thr) residues, or sometimes to hydroxylysine. 4. (b) i. Give the classification of glycosaminoglycans. Glycosaminoglycans (GAGs) are long, unbranched polysaccharides consisting of repeating disaccharide units, typically containing an amino sugar (N-acetylglucosamine or N-acetylgalactosamine) and an uronic acid (glucuronic acid or iduronic acid). They are classified into several types: • Hyaluronic acid (or hyaluronan) • Chondroitin sulfate • Dermatan sulfate • Keratan sulfate • Heparan sulfate • Heparin 4. (b) ii. Discuss the pharmacodynamics of Hyaluronic acid. Pharmacodynamics describes the effects of a drug on the body and the mechanisms of its action. Hyaluronic acid (HA) is a naturally occurring GAG with diverse pharmacodynamic properties: • Lubrication and Shock Absorption: In joints, HA increases the viscosity of synovial fluid, providing lubrication and shock absorption, reducing friction and protecting cartilage. • Anti-inflammatory Effects: HA can modulate inflammatory responses by interacting with immune cells and reducing the production of pro-inflammatory mediators. • Tissue Repair and Regeneration: It plays a role in wound healing by promoting cell migration, proliferation, and angiogenesis. • Cell Signaling: HA interacts with cell surface receptors (e.g., CD44, RHAMM) to influence cell behavior, including cell growth, differentiation, and migration. • Viscosupplementation: Exogenous HA, often administered via injection, supplements endogenous HA in conditions like osteoarthritis, improving joint function and reducing pain. 5. (a) i. What is a gene knockout? A gene knockout is a genetic technique in which one of an organism's genes is inactivated or deleted from its genome. This is typically achieved by replacing a functional gene with an inactive copy, leading to a loss of function for that specific gene. 5. (a) ii. Explain the types and uses of a gene knockout. Types of gene knockouts include: • Conventional (Germline) Knockout: The gene is inactivated in all cells of the organism from conception. • Conditional Knockout: The gene is inactivated only in specific tissues or at specific developmental stages, often using systems like Cre-loxP recombination. • Inducible Knockout: The gene inactivation can be turned on or off by an external stimulus, such as a drug. Uses of gene knockouts: • Studying Gene Function: By observing the phenotypic changes in a knockout organism, researchers can infer the normal function of the deleted gene. • Disease Modeling: Knockout animals can serve as models for human genetic diseases, allowing for the study of disease progression and testing of potential therapies. • Drug Target Identification: Knockouts can help identify genes whose inactivation might be beneficial in treating diseases, thus serving as potential drug targets. 5. (b) i. Write briefly on gene knockout by mutation and gene silencing. Gene knockout by mutation involves permanently altering or deleting a gene sequence in the genome, typically leading to a complete and irreversible loss of the gene's function. This is often achieved through homologous recombination or CRISPR/Cas9 gene editing, resulting in a stable genetic change that is passed on to subsequent cell generations. Gene silencing, on the other hand, refers to the temporary reduction or inhibition of gene expression without altering the underlying DNA sequence. This can be achieved through mechanisms like RNA interference (RNAi), where small RNA molecules (siRNA or shRNA) target specific mRNA molecules for degradation or inhibit their translation, thereby preventing protein synthesis. Gene silencing is reversible and does not involve permanent genetic modification. 5. (b) ii. Differentiate between gene knock-out and knock-in. • Gene Knock-out: This technique involves the inactivation or complete deletion of a specific gene from an organism's genome. The primary goal is to eliminate the function of a gene to study its role by observing the resulting phenotypic changes. • Gene Knock-in: This technique involves the insertion of a new gene or the replacement of an existing gene with a modified version (e.g., a human gene, a mutated allele, or a reporter gene) into a specific locus in the genome. The purpose is often to introduce a specific genetic change, express a foreign protein, or study the effects of a particular mutation in a controlled manner. Send me the next one 📸