Chapter 27: Bacteria and Archaea Flashcards
what are prokaryotes
single-celled organisms that make up domain bacteria and archaea
what environments are prokaryotes adapted to
diverse and extreme environments (too acidic, salty, cold, hot)
what is the most abundant organism on Earth
prokaryotes
who were the first organisms to inhibit the Earth
prokaryotes
what is biofilm
one or more prokaryotes grow on diff. surfaces
which is bigger prokaryotic cells or eukaryotic cells
eukaryotic cells
what shapes do prokaryotic cells come in
spheres(cocci), rods(bacilli) and spirals(spirilla)
what do nearly all prokaryotes have
cell wall
what is the function of the cell wall
maintain shape
protect the cell
prevent it from bursting in hypotonic environment
what do most bacterial cell walls contain
peptidoglycan
what is peptidoglycan
network of sugar polymers cross-linked by polypeptides
what is a polypeptide
polymer of proteins
what are eukaryote cell walls made of
cellulose or chitin
cellulose
a polysaccharide sugar that is a fiber and is found in fruit and veggies
what is chitin
polysaccharides and forming the major constituent in the exoskeleton of arthropods and the cell walls of fungi.
what is gram stain
used by scientists to classify bacteria by cell wall composition
what is gram-positive
bacteria have SIMPLE walls have LARGE amounts of peptidoglycan
what is gram-negative
bacteria have less peptidoglycan are more complex with an outer membrane that contains lipopolysaccharides
what are lipopolysaccharides
complex molecule that contains both lipid and polysaccharide parts
what is the peptidoglycan layer important for
cell wall structural integrity( primary component of the wall)
what do antibiotics do to peptidoglycan
target them and damage the bacterial cell walls
what are beta-lactam antibiotics
a broad class of antibiotics that includes penicillin derivatives, cephalosporins
are B-lactam antibotics bacteriocidal?
yes, they inhibit the synthesis of the peptidoglycan layer of bacterial cell walls
what are glycopeptide antibiotics
include VANCOMYCIN, teicoplanin, telavancin, bleomycin, ramoplanin, and decaplanin
what do glycopeptide antibiotics do
used to treat multidrug-resistant Gram-positive pathogens by inhibiting peptidoglycan synthesis of the bacteria cell walls
which gram bacteria is more resistant to antibiotics
gram-negative bacteria
why are gram-negative bacteria more resistant to antibiotics
they have a largely impermeable cell wall and the wall is more complex, so they can’t let a lot of things in
what is the sticky OUTER LAYER of a polysaccharide
capsule or slime layer is present in some prokaryotes
difference between capsule and slime layer
capsule if dense is well defined
slime layer: not well organized
what do both the slime layer can capsule do
enable attachment to the substrate or other individuals, and can shield pathogenic bacteria from the host immune system
when do bacteria form inactive endospores
when water or nutrients are lacking
what can endospores do
withstand extreme conditions and remain viable for centuries
prokaryotes have hairlike appendages called what
fimbriae
what do fimbriae do
allow them to stick to their substrate
what is pili (sex pili)
longer than fimbriae
- pulls cells together and enables the exchange of DNA
what stucture is commonly used by prokaryotes for movement
flagella
where are flagella on prokaryotes
may be scattered
concentrated at one or both ends
what is bacterial flagella composed of
- 42 different proteins
- motor, hook. filament