Unit 1. Introduction to Cell Biology PDF

Cell biology is the study of cell structure and function, identifying the Cell as the fundamental unit of life. Main subfields within cell biology: I. The study of cell energy and the biochemical mechanisms that support cell metabolism. II. The genetics of the cell and its tight interconnection w...

Cell biology is the study of cell structure and function, identifying the Cell as the fundamental unit of life. Main subfields within cell biology: I. The study of cell energy and the biochemical mechanisms that support cell metabolism. II. The genetics of the cell and its tight interconnection with the proteins controlling the release of genetic information from the nucleus to the cell cytoplasm. III. The structure of cell components, known as subcellular compartments. IV. Cell communication and signaling, concentrating on the messages that cells give to and receive from other cells and themselves. V. The cell cycle, the rotation of phases beginning and ending with cell division and focused on different periods of growth and DNA replication. The starting point for cell biology might be considered the 1830s. Historical brackground Robert Hooke, 1665 Discovered the external structure of cell when he described the cavities formed by the cell wall. Brown, 1831 Schleiden, 1838 Their discoveries allow to postulate the concept of cell as a protoplasmic mass, limited by a cell membrane and with the presence of a nucleus. Schwann, 1839 Hooke Schwann Schleiden Established the omnis cellula ex cellula and that the starting point of the diseases is the cell . Father of the Cellular Pathology Rudolf Virchow, 1855 Walther Fleming, 1880 Virchow Studied the process of cell division and the distribution of chromosomes in the daughter cell by the process of mitosis. W. Fleming Father of cytogenetics Illustrations of cells with chromosomes and mitosis. Louis Pasteur (1822-1895) One hundred years after the discovery of microorganisms by Leeuwenhoek, the spontaneous generation was still valid. Spontaneous generation is the hypothesis that some vital force contained in or given to organic matter can create living organisms from inanimate objects. Louis Pasteur ended the debate of the spontaneous generation with his famous swan-neck flask experiment, which allowed air to contact the broth. Microbes present in the dust were not able to navigate the tortuous bends in the neck of the flask. Flask with the broken neck: microorganisms appeared. Pasteur proved to the world that life could only come from other life. Cell Theory: • • It arises with the development of the optical microscope It was definitely accepted with Pasteur’s experiments Cell theory 1. All living organisms are formed by cells. 2. All cells come from preexisting cells, by division of them (Omnis cellula e cellula). 3. All cells are similar between them but not identical. 4. Cells are the basic unit of life. Each cell contains all basic hereditary information to: i) control their own cycle, development and functions. ii) transfer that information to the next generation. MORPHOLOGICAL AND FUNCTIONAL UNIT OF ONE ORGANISM THE CELL IS THE ELEMENT WITH A MINIMUM SIZE WHICH CAN BE CONSIDERED AS AN ORGANISM Considering the cell organization, the organisms can be classified as: ACELLULAR: CELLULAR: VIRUS PROKARYOTIC EUKARYOTIC Basic properties and functions of cells Production and use of energy Nutrition Growth and evolution Transport Reproduction Organization Response to stimulus Comunication Differentiation Self-regulation capacity Cells are complex and highly organized Basic properties and functions of cells Metabolic capacity: Cells use and produce matter and energy. Self-replication: Reproducción Cells have a genetic program by which they can replicate and transmit the genetic information to new cells. Organization and complexity: Different cells do different functions. Relationship with the environment and other Comunicación cells: Allows the exchange of matter, energy and information with external medium. Response to stimulus: Changes in shape and movement. Self-regulation Cell types. Similarity and Diversity Blood cells Neurons Plant cells Bacteria Eukaryotes and Prokaryotes Prokaryotes Are the Most Diverse and Numerous Cells on Earth • Prokaryotes are typically spherical, rodlike, or corkscrew-shaped • Are also small—generally just a few micrometers long • Prokaryotes often have a tough protective coat, or cell wall, surrounding the plasma membrane, which encloses a single compartment containing the cytoplasm and the DNA. • Quick reproduction, • Populations of prokaryotic cells can evolve fast, rapidly acquiring the ability to use a new food source or to resist being killed by a new antibiotic. PROKARYOTIC CELL • Capsule - outer sticky protective layer • Cell Wall - rigid structure which helps the bacterium maintain its shape this is in NO way the same as the cell wall of a plant cell • Plasma membrane - separates the cell from the environment • Mesosome - infolding of plasma membrane to aid in compartmentalization • Nucleoid - region where DNA is found. Circular Double strand of DNA-Chromosome Small circular DNA-plasmid (resistance to antibiotics) • Cytoplasm semi-fluid cell interior no membrane-bound organelles location for metabolic enzymes location of ribosomes for protein synthesis CLASSIFICATION OF BACTERIA The cell wall is composed of layers of peptidoglycan, a complex of proteins and oligosaccharides. Animal cell Compartimentalization PROKARYOTIC CELL EUKARYOTIC CELL LACK NUCLEAR ENVELOPE NUCLEAR ENVELOPE WITH CHROMOSOME SINGLE CHROMOSOMES MULTIPLES LACK NUCLEOLUS DIVISION AMITOTIC (binary) LACK MITOCHONDRIA NUCLEOLUS WITH DIVISION MITOSIS / MEIOSIS MITOCHONDRIA WITH LACK CHLOROPLASTS CHLOROPLASTS PRESENT IN PLANT CELLS LACK MEMBRANE ORGANELLES MEMBRANE ORGANELLES WITH Features from Eukaryotes shared with Prokaryotic cells • Rigid cell wall Plant cells, some Fungi, some Protists Animal cells lack cell wall • Plasma membrane • Cytoplasm with ribosomes • Nuclear material Acellular Forms •VIRUSES •VIROIDS •PRIONS VIRUS EBOLA BACTERIOPHAGE VIRUS ZIKA VIRUS H5N1 (FLU) ACELLULAR FORMS: VIRUSES from the latin word virus, toxin or poison Viruses are intracellular parasites Infect host cells producing multiple copies of themselves, destroying the cell. Size: 24-300 nm (electron microscope) Geometric forms: crystallized HIV Genetically modified viruses often are used to carry foreign DNA into a cell. Because of the extensive use of viruses in cell biology research. Viruses have potential as therapeutic agents. Recommendation: watch film Contagion, 2011 Directed by Steven Soderbergh, VIRUS STRUCTURE Nucleic acid, containing the genetic information of the virus for selfreplication. Types of nucleci acid: -DNA, -RNA Capsid (are proteins) which involves the nucleic acid. The capside is organized in capsomers. These capsomers can be organized to give different type of structures. Several virus contain an outer membrane, that is a lipid bilayer (belongs to the host cell). Naked virus: without outer membrane Enveloped virus: the outer membrane is needed to infect the cells. 3 TYPES OF VIRUS: attending to the host cell 1- Bacteriophage 2- Animal or Plants virus 3- Retrovirus RNA PRIONS Prions are infectious proteins that cause neurodegenerative diseases. PrPC PrPSC CAUSE: Misfolding of of the cellular prion protein (PrPC). PrPC is characterized by a high α-helical content and conversion in a β-sheet rich conformer (PrPSC) transforms it into an infectious protein. CONSEQUENCES OF PRION DISEASES: The abnormal folding of the prion proteins leads to brain damage. Prion diseases are usually rapidly progressive and always fatal. HUMAN PRION DISEASES Creutzfeldt-Jakob Disease (CJD) Variant Creutzfeldt-Jakob Disease (vCJD) Kuru ANIMAL PRION DISEASES Bovine Spongiform Encephalopathy (BSE) Chronic Wasting Disease (CWD) Scrapie Transmissible mink encephalopathy