Simple Pharmanotes

  Cellular level of organization:  Cell Signaling. Introduction: Cells need to interact with their environment and other cells around them. This is called Cell Signaling .  Single cellular organisms need to detect nutrients in their environment, and cells in multicellular organisms are involved in a complex system of communication with each other. Cells detect signals with Cell Receptors on their plasma membrane, which are usually Glycoproteins or Glycolipids.  The signaling molecule binds to the Receptor because its shape is complementary to it (Lock and Key). This then initiates a chain of reaction within the cell, leading to a response. Cell Signalling Pathways:  Cell Signalling Pathways can be classified on the basis of distance over which the signalling occurs. Endocrine Signalling. Paracrine Signalling. Autocrine Signalling. Endocrine Signalling : It involves signalling over large distances. Usually where the signalling molecule is transported in the circulatory system.

  Cellular level of organization:  Cell Junctions. Introduction: In many animal tissues (e.g., connective tissue), each cell is separated from the next by an extracellular coating or matrix. However, in some tissues (e.g., epithelium), the plasma membranes of adjacent cells are pressed together. Cell junctions primarily act as communicators between cells while also helping in anchoring the cell to the basement membrane. There are five different types of cell junctions:  Gap Junctions,  Adherens Junctions,  Hemidesmosomes,  Desmosomes, and  Tight Junctions. Tight Junction. Tight junctions are areas where the membranes of two adjacent cells join together to form a barrier.  The cell membranes are connected by strands of transmembrane proteins .  The cytoskeletons of the individual cells are linked through the tight junctions. The junctions are so tight that nothing can pass through them hence substances have to cross the cell itself. They are often present in the epithelial cell

Cellular Level of Organization:  Protein Synthesis  Introduction: Proteins are responsible for the characteristics of the cell, some form its structure while some form its functional parts. All the information for protein synthesis is stored in the DNA of the organism. DNA has the instructions for making all proteins required  in an organism but…   DNA CANNOT make proteins!   DNA doesn't leave the nucleus, but proteins are made outside the nucleus in the ribosomes which are present in the cytoplasm.  DNA is used to build RNA.  RNA leaves the nucleus and builds proteins in the ribosome.  Proteins create an organism's physical traits and functions. 3 Types of RNA are made from DNA template strand: Ribosomal RNA (rRNA) :  Used to build ribosomes. Transfer RNA (tRNA):  Used to carry amino acids from cytosol to ribosomes. Messenger RNA (mRNA):   Carries the instructions for making ONE protein from nucleus to ribosome. RNA STRUCTURE: RNA has one chain (strand) of RNA nucleotides RNA

  Cellular level of organization:  Cell Division: Meiosis. Introduction: Cell is defined as a basic structural and functional unit of the body . Cytology is a branch of science that deals with the study of cells. The animal cell is divided into two major parts as, Plasma Membrane. Subcellular organelles. Nucleus. Nucleolus Mitochondria. Golgi complex. Ribosomes. Endoplasmic reticulum. Lysosomes. Centrioles. The cell cycle, or cell-division cycle, is the series of events that take place in a cell that cause it to divide into two daughter cells.  These events include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm and other components into two daughter cells in a process called cell division. The events in the cell that include the duplication of its DNA (DNA replication) and some of its organelles, and subsequently the partitioning of its cytoplasm and other components into two daughter cells in a process