Week 3: Cellular Structures Flashcards
comonalities of prokaryotes & eukaryotes
all are composed of same biomolecules, all cells are membrane bound, all cells are fluid filled with cytoplasm, both have ribosomes
smaller cells have a larger surface to volume ratio which means
they are more efficient at metabolism
how do stains work
simple stain become positively charged in solution, they interact with the negatively charged plasma membrane which creates a contrast under the microscope
strepto
long chains
staphylo
grape like clusters
glycocalyx
gel like polysaccharide layer that typically surrounds bacterial cells
pili/fimbriae
protein fibers arranged in hollow, helical formation
flagella
thin protein tubes longer than pili, spin like propeller enabling bacterial motility
positive taxis
move towards a favourable stimulus
negative taxis
move away from negative stimulus
3 types of prokaryotic cell walls
gram +, gram -, acid fast
gram + structure
largely composed of thick layer of peptidoglycan
the penicillin family of antibiotics inhibit the formation of
pentaglycine bridges
gram - structure
contain peptidoglycan, contain outer membrane of lipopolysaccharide
LPS is recognized by the host sytem causing
fever and inflammation
LPS is also called endotoxin which can result in
endotoxic shock if gram - bacteria die too rapidly
basic stain (crystal violet)
adheres to negatively charged plasma membrane in all cell types
iodine is applied
iodine CV bind forming large crystals attached to the cell membrane
alcohol is applied followed by water
Alcohol dissolves the outer membrane in Gram negative cells and water washes
away the Iodine-CV complex
basic stain (safranin) is applied
Adheres to the negatively charged plasma membrane in Gram negative cells.
phospholipids
Unique structural property forces the hydrophobic tails
to point inwards, away from the watery cytoplasm and
extracellular fluid. Results in the formation of a bilayer
(two layers of phospholipids)
peripheral proteins
Bound to the outer surface of the membrane; perform
various functions discussed later
transmembrane proteins
Cross through both layers of the PM
endospores
allow bacteria to persist in environmentally unfavourable conditions until more favourable conditions arise
spore formation
First, the genetic material is replicated
• Unequal cell division occurs within the cell,
forming a septum between the two chromosomes
• The larger of the two compartments, then engulfs
the smaller compartment creating a double
membrane
• Peptidoglycan layers are constructed between the
two membranes and a protein coat is deposited on
top
• The cell lyses, releasing the endospore into the
environment
