Lesson 1: Functional Anatomy of Prokaryotic and Eukaryotic Cells PDF

LESSON 1: FUNCTIONAL ANATOMY OF PROKARYOTIC AND EUKARYOTIC CELLS Microorganism  Aka microbes  Inhabit environment that supports life – microbial communities  Undifferentiated, single celled or multicellular  Essential in sustaining life: provides oxygen  Pathogens - microbes cau...

LESSON 1: FUNCTIONAL ANATOMY OF PROKARYOTIC AND EUKARYOTIC CELLS Microorganism  Aka microbes  Inhabit environment that supports life – microbial communities  Undifferentiated, single celled or multicellular  Essential in sustaining life: provides oxygen  Pathogens - microbes causing diseases  Bacteria, archaea, algae  Microbiology is the study of the dominant form of life on Earth  Microbial culture - collection of cells that have been grown on a nutrient medium  Liquid or solid mixture that contains all the nutrients needed for a microbe to grow  Growth refers to increase in cell number and not in cell mass forming a colony  Viruses are not cells, survived only with the hosts Microbial Cells  Cytoplasmic membrane - permeability barrier, separates cytoplasm from outside  Cytoplasm - mixture of macromolecules, small organic molecules, inorganic ions, ribosomes  Ribosomes - protein synthesis  Cell wall - structural strength  DNA genome - full set of genes in a cell// living blueprint (chromosomes)  Genes - segments of DNA that encode protein or RNA molecule 2 fundamental cell types: 1. Prokaryotic  Bacteria & Archaea 2. Eukaryotic  Eukarya: algae, protozoa, fungi  Contains organelles 2 microbial cells: Prokaryotes  Evolved first due to the presence of RNA first in the planet  Lacks organelles  Circular DNA  No cationic proteins called histones  No nucleus  Archaea, cyanobacteria, eubacteria  Divides faster: surface area > volume  Horizontal transfers (share to the same generation): conjugation, another bacteria. Then undergoes recombination giving rise to new phenotypes  Transduction - transfer by bacteriophage (a virus) which could be generalized or specialized  Conjugation - cell to cell contact thru plasmids (circular DNA that are self replicating) or transposons (jumping genes, motile)  No meiosis, only conjugation Eukaryotes  Contain organelles   Linear DNA  Divides slower : surface area < volume  Animals and plants  Plants and fungi are the only ones that have cell wall 3 Domain Systems of Classification 1. Domain Archaea  Prokaryotes, single celled  Thrive areas with high salinity, temperature, pressure (extremophiles)  Heterotrophs (energy from other organisms) or autotrophs (make their own food) 2. Domain Bacteria  Aka Eubacteria  Prokaryotes, single celled  Heterotrophs  Most abundant  Cell walls have peptidoglycan:  N-acetylmuramic acid and N-acetylglucosamine linked by short peptides 3. Domain Eukarya  Major groups: fungi and protista Fungi  Unicellular - yeast  Multicellular - lichens (symbiotic partnership of alga and fungus), mushrooms  Heterotrophic  Lack motility  Cell walls have chitin  Most fungi have hyphae (feathery filaments for vegetative growth) Protista Algae  Polyphyletic (more than one common evolutionary ancestor)  Photoautotrophic (from sunlight)  Primarily aquatic  Unicellular  Thallophytic: No vascular system, did not undergo cell differentiation  Some are motile (flagella) Protozoans  Unicellular, motile  Free-living  Some are commensals (gets energy from host but does not affect the host at all)  Nucleus is vesicular (active transcription) Slime molds   Aka myxomycetes  Composed of acellular mass of naked protoplasm  Saprophytic (feeds on dead animals// recyclers)  Lack chitin in cell wall  Unicellular  Vegetative stage has no cell walls Water molds  Diploid nuclei  Oogamous - immobile egg + motile sperm  Saprotrophic  Flagellated reproductive cells  Most thrive in water or moist areas Viruses  Noncellular  Have RNA or DNA  Nucleic acid enclosed in protein coat or capsid. could be single or double stranded  Seen using scanning and transmission electron microscope  Cannot reproduce by itself (dependent to host) Archaea vs Bacteria  Archaea: least characterized and plays major role in recycling nitrogen  Component of membranes:  ether lipids (archaea)  ester lipids (bacteria)  Archaea and bacteria influenced the evolution of eukaryotes Cell morphology Spherical  Coccus is spherical  Diplococcus by pairs  Streptococcus is straight chain  Tetracoccus cluster of four  Sarcina cubelike  Staphylococcus is grapelike Spiral  Vibrio  Spirillum  Spirochetes Rod-shaped  Single bacillus  Diplobacilli  Streptobacilli  Palisades Other shapes  Filamentous  Star shaped  Rectangular  Hyphae BACTERIA Cytoplasmic membrane  Selective permeability  Maintains integrity - separations of inside and outside environment  Hypothetical absence: loss of control, disrupted homeostasis = cell death Cell wall (Cell envelope)  Prevent lysis: protection against osmotic pressure  Shape and rigidity  Peptidoglycan and LPS - unique to bacteria structure  Sterols in cell wall-less bacteria (mycoplasma, ureaplasma)  D-type = dextro  Gram Staining  Hans Christian Gram  to differentiate bacteria:  gram positive - thick peptidoglycan, dark purple  gram negative - thin peptidoglycan, fuchsia pink Gram Positive Cell Wall  Thick and rigid layers of peptidoglycan Teichoic acids:  (-) charged, regulate movement of cations  Regulate growth and prevent lysis  Used to identify bacteria  Types:  Lipoteichoic acids - linked to cell membrane, spans the cell wall  Wall teichoic acids - linked to peptidoglycan layer  Susceptible to antibiotics due to no outer membrane Gram Negative Cell Wall  Thin and complex of peptidoglycan  Has an outer membrane:  Bonds to lipoproteins: linked to outer membrane and periplasmic space  Periplasmic space: contains degradative enzymes and transport proteins Structure of Cell Wall 1. Outer membrane 2. Periplasmic space 3. Peptidoglycan 4. Periplasmic space 5. Cytoplasmic Membrane Components of Outer Membrane (OM)  Phospholipid bilayer  Porins - membrane protein// allows passage of small molecules  Lipoproteins - structural stability  Lipopolysaccharides (LPS) :   Polysaccharides: acts as antigens  Lipid A - endotoxin causing fever and shock  It is for protection such as evasion and barrier (against antibiotics) Structure of bacterial lipopolysaccharide 1. O-specific polysaccharide  O-antigen - present in antibiotics to avoid the host’s immune system 2. Core polysaccharide  Kdo - for structural support 3. Lipid A  Anchors LPS to membrane  2 glucosamine (N-acetylglucosamine) sugar backbone connected by phosphate groups ARCHAEA Cell walls  No peptidoglycan  Structure:  Pseudomurein in methanogens (similar to peptidoglycan)  S-layer - paracrystalline, the outermost layer Structure: glycan composition (arrangement of sugar molecules)  NAT or T : N-acetyl-D-galactosamine  NAG or G : N-acetyl-D-glucosamine  L-type is levo Unique archaeal cell wall compositions Examples:  Methanosarcina sp. - non-sulfated polysaccharides  Halococcus sp. - sulfated  Halobacterium sp. - negatively charged acidic amino acids to counteract high Na+ environment, lying at NaCl concentrations below 5%  Methanomicrobium sp. and methanococcus sp. - cell walls made of protein subunits Cytoplasmic membrane  Selective permeability  Lipid bilayer hydrophobic tail - fatty acid hydrophilic head - phosphate  Phospholipid molecule - phosphate group and lipid  Hepanoids : prokaryotes  Sterols : eukaryotes (pentacylic sterol-like molecules) Function of prokaryotic cytoplasmic membrane: 1. Osmotic or permeability barrier 2. Transport systems - specific solutes (nutrients and ions) 3. Energy generation - respiratory and photosynthetic electron transport systems, proton motive force, transmembranous ATP-synthesizing ATPase 4. Synthesis of membrane lipids and murein 5. Assembly and secretion 6. Specialized enzyme 7. Coordination 8. Chemotaxis - movement of cell to chemical gradient such as nutrients and water