CMB: An Introduction

• The Discovery of Cells:

  • Credited for the discovery of cells in 1665
  • Robert Hooke: Examined a piece of cork and observed "cells"
  • Anton van Leeuwenhoek: Observed microscopic organisms in pond water
• Tenets of the Cell Theory:

  • All organisms are made up of cells
  • The cell is the structural unit of life
  • Cells can arise only by division from a preexisting cell
  • Proposed by Matthias Schleiden, Theodor Schwann, and Rudolf Virchow
• Basic Cell Properties:

  • Cells are highly complex and organized
  • Cells possess a genetic program and the means to use it
  • Cells are capable of producing more of themselves
  • Cells acquire and utilize energy
  • Cells carry out a variety of chemical reactions
  • Cells engage in mechanical activities
  • Cells are able to respond to stimuli
  • Cells are capable of self-regulation
  • Cells evolve
• Two Fundamentally Different Classes of Cells:

  • Prokaryotic Cell
  • Eukaryotic Cell
  • Common features between prokaryotic and eukaryotic cells
  • Features of eukaryotic cells not found in prokaryotes
• Techniques and Methods Used in Cell and Molecular Biology:

  • Cell and Tissue Culture:
  • Definition
  • Applications in plant, animal, microbe, and virus studies
• Plant tissue culture is a technique used for the propagation of plants using only a small part of their living tissues, which are then grown in vitro on an artificial medium under sterile conditions
• Applications of plant tissue culture include:

  • Plant propagation
  • Germplasm preservation
  • Acceleration of plant breeding
  • Improvement of plant quality and genetic variability
  • Production of cell bioactive metabolites
• Plant cells are totipotent, capable of giving rise to any cell type, a complete embryo, or plant using only a small plant tissue
• Explant: a plant tissue sample obtained from a single mother plant or from genetically modified plant tissues
• Callus:

  • An amorphous mass of undifferentiated, loosely arranged, and actively dividing parenchymatous cells
  • Formed as a response of a plant tissue to chemical or physical lesion
  • Varies in shape, size, pigmentation, and sometimes in genetic expression
• Somatic embryos:

  • Production process known as somatic embryogenesis
  • An embryo derived from a single somatic cell or from an ordinary plant tissue
• Culture medium composition varies depending on the explant used and the output being targeted
• Most commonly used medium for plant tissue culture: Murashige & Skoog medium
• Anything that has mass and occupies space is matter
• Atoms


  Smallest particles of elements, composed of protons, neutrons, and electrons
• Molecules


  Two or more atoms bonded together
• Elements


  A pure substance consisting only of atoms that all have the same number of protons in their atomic nuclei
• Organisms are composed primarily of 6 elements: C,H,N,O,P,S
• Atomic Symbol


  Represents elements, e.g., carbon (C), hydrogen (H), mercury (Hg), copper (Cu)
• Periodic Table


  An arrangement of chemical elements based on the periodic law
• Periodic Law


  The elements when arranged in order of their atomic numbers show a periodic variation of atomic structure and of most of their properties
• Compound


  A molecule made of atoms from different elements
• Chemical Formula


  A representation of the chemical composition of a compound, e.g., CO2, H2O, C6H12O6
• Chemical Bonding


  The attractive force that binds atoms together to form molecules
• Types of Chemical Bonding

  • Covalent Bond
  • Ionic Bond
  • Hydrogen Bond
• Covalent Bond


  Sharing of electrons, characteristic of most chemicals in living things, sometimes two pairs of electrons are shared between atoms - a double covalent bond
• Ionic Bond


  Electron/s is/are transferred from one atom to another to form ions, e.g., formation of NaCl
• Hydrogen Bond


  Formed when hydrogen combines with oxygen or with another electronegative atom, weak and easily formed and broken, very important in biological systems, important in determining the structure of DNA and proteins
• Water is a polar molecule, with oxygen covalently bonded to two hydrogen atoms
• Polarity of Water


  Oxygen has a partially negative charge, hydrogen has a partially positive charge, leading to mutual attraction (hydrogen bonding) between adjacent water molecules and water and other polar molecules
• Thermal Properties of Water

  • High specific heat (amount of energy that can be absorbed for a given temperature rise)
  • High thermal conductivity (ability to rapidly conduct heat away from point of application)
• The thermal properties of water ensure it is in liquid or aqueous state over a temperature range, prevent water from cooling down or heating up too fast, and prevent localized overheating
• Water as the Universal Solvent


  Due to its high polar character, water can partially neutralize electrical attractions between charged solute molecules or ions by surrounding them with oriented water molecules (hydration shell), preventing ions from recombining to form crystal structures
• The universal solvent property of water makes it a suitable medium for the uptake and distribution of amino acids and sugars, ensuring their solubility within the cell
• Cohesion and Adhesion of Water


  Adhesion: attraction of water to solid surfaces

  Cohesion: strong mutual attraction between water molecules

  Results in high surface tension, generating turgor pressure and wall pressure, keeping cells turgid
• Water maintains the structure and function of macromolecules and the complexes they form by forming hydrogen bonds with each other and to specific monomers of a macromolecule
• Categories of Cellular Organic Molecules Based on their Metabolic Roles


  • Biomolecules
  • Building Blocks of Biomolecules
  • Metabolites
  • Molecules of Miscellaneous Function
• Biomolecules


  Also called macromolecules, huge, highly organized molecules which contain dozens to millions of carbon atoms, assume intricate shapes and perform complex tasks with great precision and efficiency, including carbohydrates, lipids, proteins, and nucleic acids
• Building Blocks of Biomolecules


  Low-molecular-weight precursors of biomolecules, including monosaccharides, amino acids, fatty acids, glycerol, and nucleotides
• Metabolites


  Compounds formed along a metabolic pathway leading to the formation of an end product