Life Individual survival Reproduction

Bacteria Archaea Protozoa Algae Plants Fungi Animals Invertebrates Vertebrates US UCA Prokaryotes Eukaryotes Single-celled

Cell Functions Maintenance –Recovery of energy from nutrients –Storage of energy –Synthesis of correct proteins and other cell components Perpetuation of self –DNA replication –Cell division Specialized functions –e.g. muscle, blood, nerve cells

The molecules of life Nucleic acids (DNA, RNA) Proteins Carbohydrates Lipids Lipoproteins, glycoproteins, vitamins….

DNA, the blueprint for the cell –Four bases, A,C,G,T –The order of the bases dictates amino acid sequence in proteins - “codes for synthesis of proteins” Double strand, coiled in Double Helix –Arranged in chromosomes –About 1 yard total in each human cell Inside nucleus RNA takes instructions from nucleus to endo- plasmic reticulum where proteins are made

DNA RNAProtein DNA + DNA Translation protein synthesis DNA Replication Cell division The Proteome Proteomics Genomics The Genome Transcription

PROTEINS Chains of amino acids Structural elements - cell walls, membranes Catalysts - enzymes Communication devices - within cells, between cells Cytokines Signal transduction factors Receptors –Vital in regulation of cell growth, replication

Schematic metabolic cycle Cellular components Nucleic acids, Carbohydrates, Protein, Fat Metabolic intermediates NADPHNADP+ Work Transport Assembly Movement Heat ATP ADP + Pi Food Carbohydrates, Fats, Glucose, Proteins Wastes CO 2, H 2 O, lactic acid ATP ADP + Pi NAD+ NADH

Viruses micrometers diameter Genetic material: ss or ds DNA, RNA Protein coat Some enzymes Lipid envelope – enveloped/non enveloped viruses Nomenclature semi-systematic –Hepatitis A Virus, HAV Need host cell for replication

The Flu Virion

Envelope: lipid bilayer membrane + glycoproteins, typically acquired from host cell membranes Capsid (protein coat): multiple copies of 1 or more proteins in an array

Life-cycle of virus Particle, virion Infects host cell Genetic material uses host’s replication apparatus to produce new viral components (capsid, core proteins, genetic material) Components assemble into viral particles, exit host cell, sometimes lysing host cell

Each type of virus has its own specific host Viruses that colonize bacteria are bacteriophage viruses (bacteriophages).

Viruses in the Environmment Must be able to survive outside host cell Non-enveloped viruses are more persistent than enveloped viruses – lipid envelope more easily damages, protein coat confers stability Enteric viruses are almost all non-enveloped –Hepatitis A, poliovirus, noroviruses, rotaviruses –transmitted by direct and indirect contact, fecally contaminated water, food, fomites and air. Respiratory viruses: adenoviruses, coronaviruses –transmitted by direct and indirect contact, air and fomites (some also by water and food).

Unicellular organisms Bacteria - procaryotes Protozoa Algae - eucaryotes Fungi

Procaryotic Cell (left) and Eucaryotic Cell (right)

Procaryotes: Bacteria and Others Unicellular organisms Simple internal organization Multiply by binary fission Diameter ~ micrometer Envelope: cytoplasmic membrane, cell wall & capsule (polysaccharide) Some have appendages: flagella: for locomotion pili: attachment to other cells for genetic transfer; virus receptor site Standard Linnean nomenclature: Genus species

Bacterial types Gram positive Gram negative Aerobes Anaerobes Facultative aerobes Rods (bacilli) Spherical (cocci) Comma-shaped (vibrios) Spiral (spirochetes)

Bacteria in the Environment Some bacteria form spores: –highly resistant to physical and chemical agents and –very persistent in the environment

Pathogenic Bacteria Pathogenic bacteria possess structures or chemical constituents that contribute to virulence properties –Outer cell membrane of Gram negative bacteria: endotoxin (fever producer) –Exotoxins –Pili: for attachment to cells and tissues –Invasins: to invade cells

Unicellular Eucaryotes: More complex internal organization: –organelles: discrete nucleus, mitochondria Wide range of sizes: 2 micrometers and larger

Protozoa Unicellular; non-photosynthetic; flexible cell membrane; no cell wall; some are parasites, have complex life-cycles Wide range of sizes and shapes; 2 micrometers to 2 mm Disease-causing: –Amoebae: Entamoeba histolytica –Flagellates: Giardia lamblia –Ciliates: Balantidum coli –Sporozoans: Plasmodium vivax –Coccidians: Cryptosporidium parvum –Microsporidia –Cyclosopora cayetanensis

Cryptosporidium parvum oocysts: ~5  m diameter Acid fast stain of fecal preparation Wet mount by differential interference contrast microscopy

Giardia lamblia cyst: ~10 x 8 micrometers

More Protozoans: Fungi Fungi (yeasts and molds): non-photosynthetic immotile; rigid cell wall Molds: grow as branched, interlacing chains or filaments (hyphae) called mycelia Yeasts: do not form mycelia grow as single cells that bud sexual reproduction possible Mitospores (conidia) of Penicillium, one of the asexual Ascomycota Yeasts

Algae Photosynthetic Rigid cell wall Simple plants, protists, protozoa, plancton, derived from cyanobacteria ? Wide range of sizes and shapes –2 micrometers and larger Some algae are harmful –Algal booms Toxins –Anabaena, anatoxins Nostoc

Helminths (Worms) Multicellular animals Some are human and/or animal parasites Eggs pass via human and animal excreta to water, food, soil. Several major groups: –Roundworms, Nematodes eg. Ascaris, Trichinella spiralis, hookworms –Flatworms Platyhelminthes: Cestodes (tapeworms): pork, beef tapeworms, and Trematodes (flukes) eg Schistosomes –Annelids (leeches) Necator (hookworm) eggs adult

Eggs hatch in soil Infective stage: larvae Penetrate skin, migrate to blood, lungs, trachea or are ingested Adults mature in intestine Attach to intestinal walls –anemia –Necator americanus, Ancylostoma duodenale (hookworm)

Trematodes Schistosomes (blood flukes) Liver fluke

Cestodes Head (scolex) attaches to tissue –beef tapeworm, Taenia saginata –pork tapeworm (T. solium) Grows in intestine

Multicellular organisms Plants Animals –Invertebrates –Vertebrates

The plasma membrane Lipid bilayer Polar Non-polar (Lipid) Protein Av. Width 7.5 nm (75 Å) Sugar Glycolipid Glycoprotein

The cell cycle G1G1G1G1 S G2G2G2G2 M G0G0G0G0A Mitosis (Cell division)

Different cell types Connective tissue, fibroblasts Endothelial cells, lining of blood vessels Epithelial cells, “outside” of several tissues Hepatocytes, liver cells Some cell populations are continually being renewed (turnover), others are “permanent”

Rat fibroblasts

Cell renewal Renewal by duplication - proliferation –eg endothelial cells –pancreas –hepatocytes ? Renewal by differentiation of stem cells –eg skin, intestinal wall, blood cells

Cell reproduction, cell development “Generic”Specialized Stem cells Differentiated cells Pluripotent stem cells Different types of differentiated cells Totipotent (embryonic) stem cells Organs, organisms ?