Prokaryotes

Question 1

what are the arrangements of COCCI?

Answer 1

coccus (singular)
diplococci (pairs)
tetrad (4)
sarcina (8)
staphylococci (cluster)
streptococci (string)

Question 2

what are the arrangements of BACILLI?

Answer 2

bacillus (singlar)
diplobacilli (pair)
streptobacilli (string)
pallisade (fence-like)
coccobacilli (short rod)

Question 3

what are the arrangements of SPIRALS?

Answer 3

spirochetes (long corkscrew)
spirilla (shorter corkscrew with flagella)
vibrio (macaroni shaped)

Question 4

what are the key ORGANELLES in a typical prokaryotic cell?

Answer 4

cytoplasm
70S ribosomes
NO mitochondria
cytoplasmic membrane
nucleoid (1-2 chromosome(s) and plasmids)
cell wall/envelope
flagella (if motile)

Question 5

what are PILI?

Answer 5

hair-like protein filaments used for ATTACHMENT or EXCHANGE OF GENETIC MATERIAL or SEX

Question 6

what are FIMBRIAE

Answer 6

shorter versions of pili, used for ADHESION

Question 7

what are STALKS?

Answer 7

attachment organelles
extensions of cell envelope and cytoplasm
secretes adhesion factors

Question 8

describe the GENETIC MATERIAL of prokaryotes

Answer 8

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

Question 9

what is HORIZONTAL gene transfer?

Answer 9

TRANSFER of genes between organisms, OUTSIDE TRADITIONAL REPRODUCTION

Question 10

what is VERTICAL gene transfer?

Answer 10

TRANSMISSION of genes from PARENT to OFFSPRING via BINARY FISSION

Question 11

what are the mechanisms for GENETIC DIVERSITY?

Answer 11

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)

Question 12

what is the FLUID MOSAIC MODEL?

Answer 12

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

Question 13

how is FLUIDITY controlled by the phospholipids in the cell membrane?

Answer 13

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

Question 14

what MOLECULE contributes to membrane FLUIDITY?

Answer 14

HOPANOIDS/HOPANES: planar, rigid, straight structures. Embedded in membranes.

Question 15

what are the differences between BACTERIAL and ARCHAEAL membranes?

Answer 15

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

Question 16

describe the CYTOPLASMIC MEMBRANE

Answer 16

diffusion BARRIER
site to ANCHOR PROTEINS
site of PROTON MOTIVE FORCE for energy conservation –> gradient

Question 17

describe the BACTERIAL CELL ENVELOPE

Answer 17

PROTECTIVE LAYER
gives the cell its SHAPE
gram negative has TWO membranes
gram positive do NOT have outer membrane (thick layer of peptidoglycan)

Question 18

describe the bacterial CELL WALL

Answer 18

made of PEPTIDOGLYCAN
aternating units of N-acetylglucosamine and N-acetylmuramic acid
can cross link D-alanine molecules via TRANSPEPTIDASE

Question 19

what is PEPTIDOGLYCAN?

Answer 19

withstand TURGOR pressure (pressure exerted by water pushing upwards)
prevents cell from BURSTING
TARGET for ANTIBIOTICS

Question 20

what are the 3 cell envelopes?

Answer 20

gram POSITIVE: THICK cell wall
gram negative two THIN cell wall
mycobacteria mycolic acid and phospholipid wall

Question 21

describe the gram POSITIVE cell WALL

Answer 21

POSITIVE = PURPLE
layers of peptidoglycan
threaded by TEICHOIC acid and LIPOTEICHOIC acids
more structural support and rigidity
more SUSCEPTIBLE TO ANTIBIOTICS

Question 22

describe the gram NEGATIVE cell wall

Answer 22

NEGATIVE = PINK
two membranes separated by PERIPLASM, containing thin PEPTIDOGLYCAN layer
outer membrane contains LIPOPOLYSACCHARIDES, TRANSMEMBRANE PROTEINS (porins), and LIPOPROTEINS

Question 23

what are LIPOPOLYSACCHARIDES?

Answer 23

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

Question 24

describe the MYCOBACTERIAL cell wall

Answer 24

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

Question 25

what is the S (surface) - layer

Answer 25

monomolecular layer of IDENTICAL proteins or glycoproteins
pores allow movement of molecules
additional protection

Question 26

describe the ARCHAEAL cell wall

Answer 26

PSEUDOPEPTIDOGLYCAN
proteinaceous S-layer which is anchored to cell membrane
can contain pseudomurein or methanochondroitin

Question 27

describe CAPSULES

Answer 27

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

Question 28

what are CYANOBACTERIA

Answer 28

produce OXYGEN
PHOTOAUTOTROPHS
fix nitrogen

Question 29

what are THYLAKOIDS

Answer 29

maximize PHOTOSYNTHETIC ability
packed with CHLOROPHYL
only in gram NEGATIVE phototrophs

Question 30

what are GAS VESICLES

Answer 30

allows microbes to FLOAT and get SUNLIGHT
collect gasses produced by metabolism