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microbiology

quiz 2

QuestionAnswer
light microscope (external structure)
electron microscope (internal structure)
Isolation of cell components fractionation, ultracentrifugation
SIMILARITIES PROKARYOTIC & EUKARYOTIC CELLS COMPOSED OF THE SAME 4 BASIC BIOLOGICAL MACROMOLECULES • UNDERGO THE SAME TYPES CHEMICAL REACTIONS • DISPLAY THE SAME CHARACTERISTICS OF LIVING ORGANISMS
DIFFERENCES:PROKARYOTIC & EUKARYOTIC CELLS AMOUNTS OF BASIC MACROMOLECULES • REACTANTS DIFFER SO END PRODUCTS OF REACTIONS DIFFER • LIVE IN A GREATER VARIETY OF ECOLOGICAL NICHES • EXHIBIT GREATER VARIETY IN THEIR BIOCHEMICAL CAPABILITIES
Nucleus prokaryote has no nucleus eukaryotic has a nucleus
genetic material prokaryotic have One circular DNA molecule, eukaryotic have chromosomes packed with proteins
Ribosomes prokaryotic have 70s ribosomes, eukarytic have 80s
cell wall prokaryotic cells have a cell wall made of peptidoglycan, plant cell wall of cellulose, fungus cell wall of chitin
membrane no sterols in prokaryotic, sterols in eukaryotic. sterols allow fluidity
Membrane bound Organelles no membrane bound organelles in prokaryote, membrane bound organelles in eukaryote.
Organisms prokaryotic cells are bacteria and archea eukaryotic cells are Animals, Plants Fungi, Protozoa, Algae
Reproduction prokaryotic cells reproduce asexually via binary fusion eukaryotic cells reproduce asexually or sexually
coccus, cocci Spherical or round shaped bacteria
bacillus, bacilli Rod shaped shaped bacteria
spirochete Corkscrew shaped bacteria, flexible, moves via axio filaments
spirillum, spirilla loose S shaped bacteria, rigid shaped, moves via polar flagella
vibrio Comma shaped
coccus Single coccus
Diplococci coccus in pairs
Streptococci coccus in chains
Tetrads coccus in groups of four
Sarcina coccus in cubical packets
Staphylococci coccus in irregular cluster
Diplobacilli Bacilli in pairs
Streptobacilli Bacilli in chains
Pleomorphism Variation in cell shape and size within a single species, could happen because of Nutritional /hereditary differences
Bacterial Appendages Motility– flagella and axial filaments Attachment or channels– fimbriae, pili
Glycocalyx surface coating of molecules external to the cell wall, made of polysaccharides/or polyproteins SIGNIFICANCE: INCREASE PATHOGENICITY
Filament ong, thin, helical structure composed of protein flagellin
Hook curved sheath
Basal body stack of rings firmly anchored in cell wall
Flagellar Mechanism of Action • Rotates 360
Monotrichous single flagellum at one end
Lophotrichous small bunches (tufts) emerging from the same site
Amphitrichous flagella at both ends of cell
Peritrichous flagella dispersed over surface of cell coming from all sides
chemotaxis positive and negative Chemical stimuli
phototaxis Light stimuli
run motion flagella rotaes Counterclockwise
tumbles motion flagella rotates clockise
FIMBRIAE & PILI COMPOSITION: protein pilin • FUNCTION: attachment; transfer of DNA • SIGNIFICANCE: increase pathogenicity or virulence
Pili Rigid tubular structure made of pilin protein • Found only in gram-negative cells • Function to join bacterial cells for partial DNA transfer called conjugation (horizontal gene transfer) (sex bridge) causes deadly bacteria to multiply quickly
Fimbriae (fimbria) Fine, proteinaceous, hairlike bristles emerging from the cell surface ( Pilin) • Function in adhesion to other cells and surface
Slime layer Glycocalyx loosely organized and attached; easily washed off
Capsule Glycocalyx highly organized, tightly attached; thick; not readily
Functions of the Glycocalyx • Protect cells from dehydration and nutrient loss • Protect cells from toxic chemicals (antibiotics, disinfectants) •can evade phagocytosis, contributing to pathogenicity • Attachment - formation of biofilms
Gram-positive bacteria thick cell wall composed primarily of peptidoglycan and cell membrane, very little space, includes techoic acid
Gram-negative bacteria outer cell membrane, thin peptidoglycan layer, and cell membrane, lots of space and lps
Function of Cell Walls -Determines cell shape - Prevents lysis due to changing osmotic pressures
Composition of Cell Walls -Peptidoglycan is the primary component: – Unique to prokaryotes in Domain Bacteria – Macromolecule composed of a repeating framework of long glycan chains cross-linked by short peptide fragments
NEGATIVE STAIN *Capsule does not take stain, so you Use simple acidic stain to color the background
Basic stain color is in the positive ion because the cell wall is made up of negative ions a basic stain will stain the cell wall
acidic stain color is in the negative ion because the cell wall is made up of negative ions a negative stain will stain the background not the cell wall
Gram-Positive Cell Wall one layer composed of peptidoglycan, teichoic acid, lipoteichoic acid thicker than gram negative no outer membrane narrow periplasmic space more penetrable
Gram-Negative Cell Wall two layer composed of lipopolysaccharides (LPS), porin proteins, peptidoglycan, Lipoproteins thinner than gram positive has an outermembrane large periplasmic space less penetrable than gram positive
GRAM STAIN PROCEDURE A differential staining procedure positive ion will retain primary stain (if primary stain is orange then the positive ion cell wall will turn orange negative ion retains the opposite color
GRAM STAIN PROCEDURE (steps) Apply Crystal Violet (primary dye), all cell walls will be stained. apply Gram’s iodine (mordant) apply Alcohol (decolorizer) apply Safranin (red dye counterstain) gram positive will be purple gram negative will be red
exotoxins made of protein, produced inside gram positive cells, then secreted out into the blood to target specific organs
endotoxins produced inside gram negative cells, are contained inside the cell until the cell dies, when cell dies the toxins are released due to the destruction of the cell wall, toxin will have a general effect on the body
Created by: Virajasaur