Medical Biology Lectures PDF

Medical Biology Lectures Fatih Akdemir, PhD Assistant Professor Ataturk University, School of Medicine Contact: [email protected]  Main Themes Cell and the organelles Cell-cell and cell-matrix interactions (multicellularit...

Medical Biology Lectures Fatih Akdemir, PhD Assistant Professor Ataturk University, School of Medicine Contact: [email protected]  Main Themes Cell and the organelles Cell-cell and cell-matrix interactions (multicellularity) Cell division Signal Transduction Molecular Biology Techniques  Main Textbooks Molecular Biology of the Cell, Alberts et al, Garland Publishing Molecular Cell Biology, Lodish et al, Scientific American You can access these books through NCBI: http://www.ncbi.nlm.nih.gov Books Please attend the lectures and take notes. Molecular Biology Techniques Nucleic Acid Isolation (DNA, RNA) Polymerase Chain Reaction (PCR) Agarose Gel Electrophoresis DNA Sequencing Gene expression profiling  Facts Concepts Techniques  The CELL basic living unit of the body  Cell Theory All known living things are made up of one or more cells. All living cells arise from pre-existing cells by division. The cell is the fundamental unit of structure and function in all living organisms. The activity of an organism depends on the total activity of independent cells. Energy flow (metabolism and biochemistry) occurs within cells. Cells contain hereditary information (DNA) which is passed from cell to cell during cell division. All cells are basically the same in chemical composition in organisms of similar species.  The Universal Features of Cells on Earth All Cells Store Their Hereditary Information in the Same Linear Chemical Code (DNA) All Cells Replicate Their Hereditary Information by Templated Polymerization All Cells Transcribe Portions of Their Hereditary Information into the Same Intermediary Form (RNA) All Cells Use Proteins as Catalysts All Cells Translate RNA into Protein in the Same Way The Fragment of Genetic Information Corresponding to One Protein Is One Gene Life Requires Free Energy All Cells Function as Biochemical Factories Dealing with the Same Basic Molecular Building Blocks All Cells Are Enclosed in a Plasma Membrane Across Which Nutrients and Waste Materials Must Pass A Living Cell Can Exist with Fewer Than 500 Genes Biological Hierarchy  The four main families of small organic molecules in cells Sugars Provide an Energy Source for Cells and Are the Subunits of Polysaccharides Fatty Acids Are Components of Cell Membranes Amino Acids Are the Subunits of Proteins Nucleotides Are the Subunits of DNA and RNA Kingdoms of organisms are related through common sequences of their ribosomal RNAs The biological universe consists of two types of cells prokaryotic cells, which lack a defined nucleus and have a simplified internal organization eukaryotic cells, which have a more complicated internal structure including a defined, membrane-limited nucleus The structure of a bacterium All prokaryotes have chromosomal DNA localized in a nucleoid, ribosomes, a cell membrane, and a cell wall.The other structures shown are present in some, but not all, bacteria Bacteria are classified into three different shapes: (A) spheres (cocci) (B) rods (bacilli) (C) (spiral cells (spirochetes)  Bacterial cell-surface structures Bacteria are also classified as Gram-positive or Gram-negative. Bacteria such as Streptococci and Staphylococci have a single membrane and a thick cell wall made of cross-linked peptidoglycan. They retain the violet dye used in the Gram staining procedure and are thus called Gram-positive. Gram-negative bacteria such as E. coli and Salmonella have two membranes, separated by a periplasmic space. The peptidoglycan layer in the cell wall of these organisms is located in the periplasmic space and is thinner than in Gram-positives; they therefore fail to retain the dye in the Gram staining procedure. The inner membrane of Gram-negative bacteria is a phospholipid bilayer, and the inner leaflet of the outer membrane is also made primarily of phospholipids; the outer leaflet of the outer membrane, however, is composed of a unique glycosylated lipid called lipopolysaccharide (LPS)  Key Points Prokaryotes lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration. Prokaryotic cell size ranges from 0.1 to 5.0 μm in diameter. The small size of prokaryotes allows quick entry and diffusion of ions and molecules to other parts of the cell while also allowing fast removal of waste products out of the cell. An animal cell  Chemical Composition of a Bacterial Cell PERCENT OF TOTAL CELL TYPES OF EACH WEIGHT MOLECULE Water 70 1 Inorganic ions 1 20 Sugars and precursors 1 250 Amino acids and precursors 0.4 100 Nucleotides and precursors 0.4 100 Fatty acids and precursors 1 50 Other small molecules 0.2 ~300 Macromolecules (proteins, nucleic 26 ~6000? acids, and polysaccharides)  Antibiotic targets Despite the large number of antibiotics available, they have a narrow range of targets, which are highlighted in yellow. A few representative antibiotics in each class are listed. Antibiotics used to treat human infections fall into one of these categories. The vast majority inhibit either bacterial protein synthesis or bacterial cell wall synthesis.  A simple viral life cycle Viruses have a small genome, made up of a single nucleic acid type— either DNA or RNA—which, in either case, may be single-stranded or double- stranded. The genome is packaged in a protein coat, which in some viruses is further enclosed by a lipid envelope. Viruses Exploit Host Cell Machinery for All Aspects of Their Multiplication SARS-CoV-2 Life Cycle Eukaryotic Cells Contain Many Organelles and a Complex Cytoskeleton A plant cell A mitochondrion and chloroplast compared  Chloroplast This photosynthetic organelle contains three distinct membranes (the outer membrane, the inner membrane, and the thylakoid membrane) that define three separate internal compartments (the intermembrane space, the stroma, and the thylakoid space). The thylakoid membrane contains all the energy-generating systems of the chloroplast, including its chlorophyll. As indicated, the individual thylakoids are interconnected, and they tend to stack to form grana. The reactions of photosynthesis in a chloroplast Water is oxidized and oxygen is released in the photosynthetic electron-transfer reactions, while carbon dioxide is assimilated (fixed) to produce sugars and a variety of other organic molecules in the carbon-fixation reactions.  A Yeast Serves as a Minimal Model Eucaryote The yeast Saccharomyces cerevisiae The reproductive cycles of the yeast S. cerevisiae Early stages of mammalian development An example of cell types: the family of connective-tissue cells  Major Cellular Events (especially during development) Cell Division and Growth Cell Death (Apoptosis) Cell Differentiation Cell Migration and Shape Cells Can Be Grown in a Culture Dish Cells Can Be Isolated from a Tissue Suspension and Separated into Different Types Composition of a Typical Medium Suitable for the Cultivation of Mammalian Cells AMINO ACIDS VITAMINS SALTS MISCELLANEOUS PROTEINS (REQUIRED IN SERUM-FREE, CHEMICALLY DEFINED MEDIA) Arginine biotin NaCl glucose insulin Cystine choline KCl penicillin transferrin Glutamine folate NaH2PO4 streptomycin specific growth factors Histidine nicotinamide NaHCO3 phenol red Isoleucine pantothenate CaCl2 whole serum Leucine pyridoxal MgCl2 Lysine thiamine Methionine riboflavin Phenylalanine Threonine Trytophan Tyrosine Valine  Cellular Organelles The Compartmentalization of Cells An electron micrograph of part of a liver cell seen in cross section The major intracellular compartments of an animal cell Secretory and endocytic pathways in a eucaryotic cell Endomembrane system Relative Volumes Occupied by the Major Intracellular Compartments in a Liver Cell (Hepatocyte) INTRACELLULAR PERCENTAGE OF TOTAL COMPARTMENT CELL VOLUME Cytosol 54 Mitochondria 22 Rough ER cisternae 9 Smooth ER cisternae plus 6 Golgi cisternae Nucleus 6 Peroxisomes 1 Lysosomes 1 Endosomes 1 Relative Amounts of Membrane Types in Two Kinds of Eucaryotic Cells MEMBRANE TYPE PERCENTAGE OF TOTAL CELL MEMBRANE LIVER HEPATOCYTE* PANCREATIC EXOCRINE CELL* Plasma membrane 2 5 Rough ER membrane 35 60 Smooth ER membrane 16