Prokaryotes & Eukaryotes

Domains of living organisms Bacteria Archaea Eucarya Single-celled, prokaryotic organisms Complex single and multi-celled, eukaryotic organisms

Prokaryotes vs Eukaryotes

Size and Shape of Bacteria Epulopiscium fishelsoni Surgeonfish symbiont (0.6 mm) Paramecium

Size and Shape of Bacteria Pleomorphic

Rod-Shaped Bacteria

Spherical Bacteria

Spiral-Shaped Bacteria

Surface to Volume Ratio S/V ratio Coccus < Rod 생존력 비교 건조 환경: 빈영양 환경: Determination of presence and significance of pathogenic organisms in food, water, and air Fate and movement

Plasmid

Appendages (세포외 부속기관) • common in bacteria • for motility and attachment to surfaces Flagellum (편모) movement through an aqueous medium

Appendages (세포외 부속기관) 2. Fimbria - numerous short surface appendage - aid the cell in attachment to surface 3. Pilus - less numerous than fimbria but longer - only found in gram negative bacteria - involved in a mating process (conjugation)

Cell Envelope • protection of cells from external environment • glycocalyx, cell wall, cell membrane could be missing • account for as much as 50% of the cell mass Glycocalyx a coating of macromolecules that surround the cell wall (1) slime layer (2) capsule

(1) slime layer : loose informal aggregation of carbohydrates

(2) Capsule : a more rigid layer of protein that is bonded to the cell wall

Endospore-forming, Gram-Positive bacteria Bacillus Aerobic or facultative anaerobic Clostridium Strictly anaerobic (no cytochrome, ETS) fermentative Bacillus subtilis B. popilliae B. Thuringiensis (BT toxin) Clostridium botulinus C. butyricum C. aceticum C. tetani

2. Cell wall - determines the shape of the cell - gives the cell structural support - protects the cell from rupturing caused by the intake of water by osmosis

Gram Positive cell wall

Gram negative cell wall

(cytoplasmic membrane) Cell Membrane (cytoplasmic membrane) • thin, flexible structure ( ~ 5nm) • general composition: lipid bilayer - phospholipids (30 – 40%) - proteins ( ~ 60%)

• controls what gets into and out of the cell  critical barrier between the cell interior and the environment - nonpolar small molecules (water) : freely pass

others: through protein channels • involved in energy production (respiration & photosynthesis)

Cell Protoplasm • consists of metabolites and nutrients in solution • major constituent: water • not true nucleus or nuclear membrane - nucleoid: a dense area of material - DNA: known as chromosome a single circular molecule of double-stranded DNA unique nucleic acid sequence  tool of detection

Length of a cell: ~ 2 m Length of DNA: 1200 m

- Plasmid: smaller accessory pieces of DNA * codes for unique characteristics heavy metal resistance ability to degrade a toxic organic compounds - Ribosomes: particles responsible for protein synthesis size: 70S unit (50S subunit + 30S subunit) ribosomal RNA (60%) + protein (40%) unique sequence to the bacterial cell type  important in the identification of bacteria

A View of the Eukaryotic Cell

enclosed by double layered lipid envelope pores: transport of substances nucleolus - sites of rRNA synthesis DNA organized by histones  chromatin  chromosome

Chloroplasts Found in algae and green plants Membrane enclosed structure Contains chlorophyll Contains other enzymes required for photosynthesis Thylakoids; chlorophyll-containing flattened sacs Grana; stacks of thylakoids Have DNA (circular) Have ribosomes Divide by binary fission

Mitochondria Generates ATP Double membrane - structure similar to plasma membrane Inner membrane - complex folds (cristae), large surface area Center is matrix Reactions occur on cristae - ATP generation Have DNA (circular) Have own ribosomes Divide by binary fission

Ribosomes – rRNA and Protein

F6.38

The Endoplasmic Reticulum Rough ER - studded with ribosomes Protein entry point Modifications made, lipid and carbohydrates attached Smooth ER - no ribosomes More enzymatic diversity Synthesize lipids, oils, phospholipids, steroids

The Golgi Complex Lysosomes Single membrane many digestive enzymes fusion with phagosome kill bacteria Receives proteins transported from RER Mail station of the cell ; post-translational modification determines fate of protein packaged into secretory vesicle