Page 3
Semester 1: M.Sc. Biotechnology Syllabus 2023-2024
Introduction to cell Biology- Basic properties of cells- Cellular dimension-Size of cells and their composition-Cell origin and Evolution Endosymbiotic theory Microscopy types and its Application in cell biology
Introduction to Cell Biology
Basic Properties of Cells
Cells are the fundamental units of life. They possess a membrane that encloses cytoplasm and organelles. Key properties include metabolism, growth, reproduction, and response to stimuli.
Cellular Dimension
Cells vary significantly in size. Most cells range from 1 to 100 micrometers, with exceptions like nerve cells. Larger cells are often more complex and specialized.
Size of Cells and Their Composition
Cell size affects function. Larger cells require more resources and are often less efficient. The cellular composition includes water, organic molecules, and ions.
Cell Origin and Evolution
Cells originated through chemical processes on early Earth. The theory of abiogenesis explains how simple molecules formed more complex structures.
Endosymbiotic Theory
This theory proposes that certain organelles, notably mitochondria and chloroplasts, originated from free-living prokaryotes that entered into symbiotic relationships with ancestral eukaryotic cells.
Microscopy: Types and Applications
Microscopy techniques include light microscopy, electron microscopy, and fluorescence microscopy. These methods are essential for studying cell structure and function, allowing visualization of cellular components at different scales.
Organelles of the eukaryotic cell and its functions Biomembranes - structural organization and the transport systems Passive, Active and Bulk transport, Cell-Cell adhesion- Cell junctions, Extra cellular matrix
Organelles of the eukaryotic cell and its functions
Nucleus
The nucleus is the control center of the cell, containing the cell's genetic material (DNA). It regulates gene expression and mediates the replication of DNA during the cell cycle.
Mitochondria
Mitochondria are known as the powerhouses of the cell, responsible for producing ATP through cellular respiration. They also play a role in regulating metabolic processes and apoptosis.
Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a network of membranes involved in protein and lipid synthesis. The rough ER is studded with ribosomes for protein synthesis, while the smooth ER is involved in lipid synthesis and detoxification.
Golgi Apparatus
The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles. It plays a critical role in processing and transporting cellular materials.
Lysosomes
Lysosomes are membrane-bound organelles containing enzymes that digest waste materials and cellular debris. They help in recycling cellular components.
Peroxisomes
Peroxisomes contain enzymes that participate in metabolic reactions, including the breakdown of fatty acids and detoxification of hydrogen peroxide.
Cytoskeleton
The cytoskeleton provides structural support to the cell, helping maintain its shape and facilitating movement. It is composed of microfilaments, intermediate filaments, and microtubules.
Plasma Membrane
The plasma membrane is a selectively permeable barrier that regulates the entry and exit of substances, thereby maintaining homeostasis.
Genome organization in Eukaryotes, DNA Replication, Transcription, and Translation and post translational Modification. Synthesis, sorting and trafficking of proteins site of synthesis of organelle and membrane proteins transport of secretary and membrane proteins across ER post-translational modification, protein glycosylation, mechanism and regulation of vesicular transport golgi and post- golgi sorting and processing receptor mediated endocytosis Synthesis of membrane lipids
Genome organization in Eukaryotes, DNA Replication, Transcription, and Translation, Post translational Modification
Genome Organization in Eukaryotes
Eukaryotic genomes are organized into linear chromosomes located within the nucleus. Chromatin, a complex of DNA and proteins, exists in two forms: euchromatin, which is loosely packed and transcriptionally active, and heterochromatin, which is densely packed and transcriptionally inactive. Nucleosomes, consisting of DNA wrapped around histone proteins, play a critical role in the compaction and regulation of DNA.
DNA Replication
DNA replication in eukaryotes occurs during the S phase of the cell cycle. It involves unwinding the double helix, synthesizing new strands using DNA polymerases, and ensuring fidelity through proofreading mechanisms. Origin recognition complexes initiate replication at specific sites on the DNA, and replication proceeds bidirectionally from these origins.
Transcription
Transcription is the process by which RNA is synthesized from a DNA template. In eukaryotes, transcription occurs in the nucleus and involves the assembly of transcription factors and RNA polymerase at promoters. Eukaryotic mRNA undergoes capping, polyadenylation, and splicing to become mature mRNA before it is exported to the cytoplasm.
Translation
Translation is the process by which ribosomes synthesize proteins from mRNA. It occurs in the cytoplasm and involves initiation, elongation, and termination phases. Transfer RNA (tRNA) molecules bring amino acids to the ribosome, where the mRNA sequence is translated into a polypeptide chain according to the genetic code.
Post Translational Modification
Post translational modifications (PTMs) significantly impact protein function and regulation. Common PTMs include phosphorylation, glycosylation, ubiquitination, and methylation. These modifications can alter protein stability, activity, localization, and interactions with other molecules. PTMs are crucial for the functional diversity of proteins.
Synthesis, Sorting, and Trafficking of Proteins
Proteins are synthesized on ribosomes in the cytoplasm. For proteins destined for secretion or membrane incorporation, translation occurs on ribosomes bound to the endoplasmic reticulum (ER). Synthesis involves co-translational translocation into the ER lumen for proper folding and modification.
Transport of Secretory and Membrane Proteins across ER
Proteins synthesized in the ER undergo folding and post-translational modifications before being transported to the Golgi apparatus in transport vesicles. The process relies on signal sequences that direct proteins to their respective locations.
Post-Translational Modification and Protein Glycosylation
Within the ER and Golgi, proteins undergo glycosylation, a type of PTM where sugar moieties are added. This process is critical for protein stability, recognition, and targeting. Glycoproteins play essential roles in cell signaling and immunity.
Mechanism and Regulation of Vesicular Transport
Vesicular transport is regulated by various protein coatings, including clathrin, COPI, and COPII, which help form vesicles that bud off from membranes. These vesicles then transport proteins to their destinations, ensuring proper cellular localization.
Golgi and Post-Golgi Sorting and Processing
The Golgi apparatus modifies, sorts, and packages proteins received from the ER. It plays a key role in glycosylation and other modifications before proteins are sent to their final destinations, whether within the cell or outside.
Receptor Mediated Endocytosis
Receptor-mediated endocytosis is a process by which cells internalize molecules by engulfing them with membrane invaginations that pinch off to form vesicles. This mechanism is essential for nutrient uptake, signal transduction, and the sequestering of extracellular pathogens.
Synthesis of Membrane Lipids
Membrane lipids, including phospholipids and cholesterol, are synthesized in the smooth ER. These lipids are essential for forming cellular membranes and play roles in membrane fluidity and signaling.
Nucleus Nuclear envelope Nuclear pore complexes-nuclear matrix organization of chromatin supercoiling, linking number, twist - nucleosome and high order of folding and organization of chromosome Solenoid and Zigzag model-Global structure of chromosome Lamp brush and polytene chromosomes
Nucleus and Chromatin Structure
Nucleus
The nucleus is a membrane-bound organelle in eukaryotic cells that contains the genetic material. It plays a crucial role in regulating gene expression and mediating the replication of DNA.
Nuclear Envelope
The nuclear envelope consists of two lipid bilayer membranes, the inner and outer membranes, that encase the nucleus. It provides structural support and acts as a barrier to protect the genetic material.
Nuclear Pore Complexes
Nuclear pore complexes are large protein structures embedded in the nuclear envelope. They regulate the transport of molecules between the nucleus and the cytoplasm, allowing selective exchange of RNA and proteins.
Nuclear Matrix
The nuclear matrix is a fibrous network within the nucleus that provides structural support and organizes chromatin. It plays a role in DNA replication, transcription, and the spatial organization of the genome.
Organization of Chromatin
Chromatin is composed of DNA and proteins, primarily histones. It can be categorized into euchromatin (less condensed, transcriptionally active) and heterochromatin (highly condensed, transcriptionally inactive).
Supercoiling and Linking Number
Supercoiling refers to the twisting of the DNA double helix that can occur during replication and transcription. The linking number is a topological property representing the number of times two strands of DNA are intertwined.
Twist and Nucleosome Structure
The twist refers to the helical turn of the DNA double helix. Nucleosomes are the fundamental units of chromatin, consisting of DNA wrapped around histone proteins, creating a compact structure.
Higher Order Folding and Organization of Chromosomes
Higher order folding involves the organization of chromatin into more compact structures such as loops and domains, essential for efficient packaging of DNA into chromosomes.
Solenoid and Zigzag Models
The solenoid model depicts chromatin fibers arranged in a spiral, while the zigzag model suggests a more regular, alternating pattern, both important for understanding chromosome structure.
Global Structure of Chromosomes
Chromosomes are highly organized structures that ensure accurate segregation during cell division. Their 3D configuration within the nucleus is crucial for gene regulation and chromatin accessibility.
Lampbrush Chromosomes
Lampbrush chromosomes are found particularly in oocytes and exhibit extensive lateral loops of chromatin, indicative of active transcription and gene expression during oocyte development.
Polytene Chromosomes
Polytene chromosomes are giant chromosomes formed by the replication of DNA without cell division, often found in the salivary glands of certain insects. They are useful for studying gene expression and chromatin structure.
Molecular basis of eukaryotic cell cycle, Regulation and cell cycle check points Programmed cell death Apoptosis Cell-Cell signaling-signaling molecules, types of signaling, signal transduction pathways GPCR-cAMP, IP3 , RTK, MAP Kinase, JAK-STAT, Wnt Pathway
Molecular basis of eukaryotic cell cycle and signaling
Molecular Basis of Eukaryotic Cell Cycle
The eukaryotic cell cycle consists of several phases: G1, S, G2, and M. Each phase is tightly regulated to ensure proper cell division. Key molecules involved in the regulation include cyclins and cyclin-dependent kinases (CDKs). These proteins regulate the checkpoints in the cell cycle, ensuring that DNA is replicated correctly and that cells are ready to divide.
Regulation and Cell Cycle Checkpoints
Cell cycle checkpoints are critical control mechanisms that ensure proper progression through the cell cycle. Major checkpoints include the G1/S checkpoint, G2/M checkpoint, and the spindle assembly checkpoint. These checkpoints assess DNA integrity, replication completeness, and proper chromosome alignment, preventing potential errors in cell division.
Programmed Cell Death - Apoptosis
Apoptosis is a form of programmed cell death that plays a vital role in maintaining homeostasis and eliminating damaged cells. It is characterized by distinct morphological changes and biochemical processes, including DNA fragmentation and chromatin condensation. Key pathways involved in apoptosis include intrinsic and extrinsic pathways that activate caspases, leading to cell death.
Cell-Cell Signaling
Cell-cell signaling is essential for coordinating cellular responses within tissues. Signaling molecules (ligands) bind to specific receptors on target cells to elicit a response. Types of signaling include autocrine, paracrine, endocrine, and juxtacrine signaling, each serving different functions in cellular communication.
Signal Transduction Pathways
Signal transduction pathways involve a series of molecular events that translate extracellular signals into cellular responses. Key pathways include GPCR-cAMP, which activates protein kinases; IP3 pathway, leading to calcium release; RTK pathway, involved in cell growth and differentiation; MAP Kinase pathway, critical in response to growth signals; JAK-STAT pathway, pivotal in cytokine signaling; and Wnt pathway, essential in developmental processes.
Cancer Biology Multistage cancer development Mitogens, carcinogens, oncogenes and proto- oncogenes, tumor suppressor genes-Rb, p53, Apoptosis and significance of apoptosis
Cancer Biology Multistage Cancer Development
Introduction to Cancer Biology
Cancer biology studies the mechanisms of cancer development, progression, and metastasis. Key concepts include the understanding of genetic mutations, cellular behavior, and the microenvironment that supports tumor growth.
Multistage Cancer Development
Cancer develops through a multistage process involving the accumulation of genetic alterations, leading to the transformation of normal cells into malignant ones. Stages include initiation, promotion, and progression.
Mitogens and Carcinogens
Mitogens are substances that stimulate cell division whereas carcinogens are agents that can cause cancer. Understanding their roles is crucial for studying how normal cells can become cancerous.
Oncogenes and Proto-oncogenes
Oncogenes are mutated forms of proto-oncogenes, which normally help regulate cell growth and division. Mutations that activate proto-oncogenes can lead to uncontrolled cell proliferation.
Tumor Suppressor Genes
Tumor suppressor genes such as Rb and p53 help regulate cell cycle and promote apoptosis. When these genes are mutated or lost, it can lead to increased tumor formation.
Role of Rb and p53
Rb gene regulates the cell cycle by controlling the transition from G1 to S phase. p53 is known as the guardian of the genome, as it responds to DNA damage and can initiate apoptosis or cell cycle arrest.
Apoptosis and Its Significance
Apoptosis is programmed cell death, an essential process to eliminate damaged cells. Dysregulation of apoptosis can contribute to cancer development by allowing abnormal cells to survive.
Conclusion
Understanding the interplay between oncogenes, tumor suppressor genes, and the processes of mitogenesis and apoptosis is key in cancer biology and offers insights for therapeutic approaches.
