Prokaryotes Flashcards
what are the arrangements of COCCI?
coccus (singular)
diplococci (pairs)
tetrad (4)
sarcina (8)
staphylococci (cluster)
streptococci (string)
what are the arrangements of BACILLI?
bacillus (singlar)
diplobacilli (pair)
streptobacilli (string)
pallisade (fence-like)
coccobacilli (short rod)
what are the arrangements of SPIRALS?
spirochetes (long corkscrew)
spirilla (shorter corkscrew with flagella)
vibrio (macaroni shaped)
what are the key ORGANELLES in a typical prokaryotic cell?
cytoplasm
70S ribosomes
NO mitochondria
cytoplasmic membrane
nucleoid (1-2 chromosome(s) and plasmids)
cell wall/envelope
flagella (if motile)
what are PILI?
hair-like protein filaments used for ATTACHMENT or EXCHANGE OF GENETIC MATERIAL or SEX
what are FIMBRIAE
shorter versions of pili, used for ADHESION
what are STALKS?
attachment organelles
extensions of cell envelope and cytoplasm
secretes adhesion factors
describe the GENETIC MATERIAL of prokaryotes
1-2 CHROMOSOMES: circular, haploid, supercoiled by Nucleoid-Asscoaiated Proteins (NAPs), histone-like anchoring proteins, very little non coding DNA, no introns
PLASMID(S): extra chromosomal DNA, small, circular, double stranded, much smaller than chromosomes, additional DNA
chromosomes and plasmids replicate AUTONOMOUSLY
what is HORIZONTAL gene transfer?
TRANSFER of genes between organisms, OUTSIDE TRADITIONAL REPRODUCTION
what is VERTICAL gene transfer?
TRANSMISSION of genes from PARENT to OFFSPRING via BINARY FISSION
what are the mechanisms for GENETIC DIVERSITY?
TRANSFORMATION: cell uptakes DNA from ENVIRONMENT
TRANSDUCTION: DNA transfers through BACTERIOPHAGES that INFECT bacteria (narrow range of specificity)
CONJUGATION: bacteria can transfer DNA between cells via PILI (do not need to be same species)
what is the FLUID MOSAIC MODEL?
membrane composed of a PHOSPHOLIPID BILAYER and EMBEDDED PROTEINS
GYLCOLIPID: used by antibodies to recognize bacteria
INTEGRAL PROTEIN: transport + communication
PERIPHERAL PROTEIN: bound to cytosol
LIPID ANCHORED PROTEINS
how is FLUIDITY controlled by the phospholipids in the cell membrane?
through SATURATED and UNSATURATED fatty acid tails
SATURATED are better for HOT temperatures - more rigid, higher melting point
UNSATURATED (double bond) are better for COLD temperatures - more fluid
what MOLECULE contributes to membrane FLUIDITY?
HOPANOIDS/HOPANES: planar, rigid, straight structures. Embedded in membranes.
what are the differences between BACTERIAL and ARCHAEAL membranes?
archaea tails have ISOPRENE CHAINS with a METHYL chain every 4 units
archaea uses ESTER bonds
archaea has a MONOLAYER membrane
archaea has LITTLE FLEXIBILITY, allowing it to survive in EXTREME condition
describe the CYTOPLASMIC MEMBRANE
diffusion BARRIER
site to ANCHOR PROTEINS
site of PROTON MOTIVE FORCE for energy conservation –> gradient
describe the BACTERIAL CELL ENVELOPE
PROTECTIVE LAYER
gives the cell its SHAPE
gram negative has TWO membranes
gram positive do NOT have outer membrane (thick layer of peptidoglycan)
describe the bacterial CELL WALL
made of PEPTIDOGLYCAN
aternating units of N-acetylglucosamine and N-acetylmuramic acid
can cross link D-alanine molecules via TRANSPEPTIDASE
what is PEPTIDOGLYCAN?
withstand TURGOR pressure (pressure exerted by water pushing upwards)
prevents cell from BURSTING
TARGET for ANTIBIOTICS
what are the 3 cell envelopes?
gram POSITIVE: THICK cell wall
gram negative two THIN cell wall
mycobacteria mycolic acid and phospholipid wall
describe the gram POSITIVE cell WALL
POSITIVE = PURPLE
layers of peptidoglycan
threaded by TEICHOIC acid and LIPOTEICHOIC acids
more structural support and rigidity
more SUSCEPTIBLE TO ANTIBIOTICS
describe the gram NEGATIVE cell wall
NEGATIVE = PINK
two membranes separated by PERIPLASM, containing thin PEPTIDOGLYCAN layer
outer membrane contains LIPOPOLYSACCHARIDES, TRANSMEMBRANE PROTEINS (porins), and LIPOPROTEINS
what are LIPOPOLYSACCHARIDES?
MAJOR PERMEABILITY BARRIER
GLYCOLIPID with 3 regions:
1. O antigen which is a repetitive polysaccharide
2. core polysaccaride
3. lipid A which anchors it to the outer membrane
ENDOTOXIN –> becomes toxic when released from a lysed cell
used to identify and classify pathogens
describe the MYCOBACTERIAL cell wall
very IMPERMEABLE, hard to gram stain
rich in mycolic acids
ARABINOGALACTAN holds together the mycolic acid and peptidoglycan layer
SLOW GROWTH, hard to kill
hydrophobic membrane
what is the S (surface) - layer
monomolecular layer of IDENTICAL proteins or glycoproteins
pores allow movement of molecules
additional protection
describe the ARCHAEAL cell wall
PSEUDOPEPTIDOGLYCAN
proteinaceous S-layer which is anchored to cell membrane
can contain pseudomurein or methanochondroitin
describe CAPSULES
consists of a coat of POLYSACCHARIDES and GLYCOPROTEINS loosely bound to cell envelope
difficult to stain
found EXTERNAL to s-layer
protection against a host’s immune system
secrete polysaccharides
what are CYANOBACTERIA
produce OXYGEN
PHOTOAUTOTROPHS
fix nitrogen
what are THYLAKOIDS
maximize PHOTOSYNTHETIC ability
packed with CHLOROPHYL
only in gram NEGATIVE phototrophs
what are GAS VESICLES
allows microbes to FLOAT and get SUNLIGHT
collect gasses produced by metabolism
