Ch 3 Microscopes and cell structure Flashcards
Capsule
A distinct gelatinous material that surrounds some microorganisms
Called slime layer if its diffuse and irregular
Most are composed of glycocalyx (polysaccharides)
Chemotaxis
movement of a cell towards or away from a certain chemical in it’s environment
Cytoplasmic membrane
Phospholipid bilayer that surrounds the cell
Endospore
A extraordinarily resistant dormant cell produced by some bacteria
Flagellum
A structure used for cell movement
Gram-negative bacteria
Cell wall with a thin layer of peptidoglycan surrounded by an outer membrane: pink stain
Gram-positive bacteria
Cell wall characterized by a thick peptidoglycan layer: stains purple
Lipopolysaccharide (LPS)
Molecule that makes up the outer layer of the outer membrane of the Gram-negative bacteria
Endotoxin
A Lipid: portion the body recognizes as a threat
O antigen: made of sugar molecules and identifies certain species
Peptidoglycan
Macromolecule that provides strength to the cell wall, found only in bacteria
Periplasim
Gel-like layer that fills the region between they cytoplasmic membrane and the outer membrane in the Gram-negative cell
Pili
Cell surface that allows it to adhere to certain surfaces
Plasmid
Extrachromasomal DNA molecule that replicates independently of the chromosome
Ribosome
Structure involved in protein synthesis
Transport system
Mechanisms used to transport nutrients and other small molecules across the cytoplasmic membrane
Light microscope
Visible light passes through a series of lenses to produce a magnified image.
Easy to use and less expensive
1’000 x
Electron Microscopes
Electron beams are used in place of visible light to produce the magnified image
Can magnify up to 100,000x
Atomic Force Microscopes
A prob moves in response to even the slightest force between it and the sample
Shows bumps and valleys of the atoms on the surface of the sample
Staining
Sample staining: dying the cell on the slide
Negative staining: Coloring the back ground behind the cell
Differential staining:
Used to distinguish different groups of bacteria: Gram staining Acid-fast staining Capsule staining Endospore staining Flagella staining Flurescent dyes and taging
Shapes of bacteria
Coccus: round Rod: round and long Vibro: short curved rod Spirillum: Short spirlla Spirochete: long helical cell
Cell Groupings
Chains
Packets: two or more planes, perpendicular
Clusters: several random planes
Cell envolope
All the surface layers of a prokaryotic cell
Proton Motive Force
Separation of protons and hydroxyl ions across a membrane creates electrochemical gradient across the membrane. The energy is harvested when protons move back into the cell
Transport systems
Facilitated: no energy and can only equalize concentration gradient
Active: Uses energy to move against the concentration gradient
Group Translocation: Uses energy and chemically alters substance being moved across the membrane
PCN vs. Lysozyme antibiotics
PCN: prevents the cross linking od adjacent glycan chains
Lysozyme: breaks existing bonds that link glycan chain
