Bacteria Structure, Function, and Pathogenicity

Question 1

What is the difference between eukaryote and prokaryote?

Answer 1

P- small, no nuclear membrane, circular chromosome, 70s ribosome (30s and 50s subunits), cell wall peptidoglycan (complex); E- large, nuclear membrane, linear multiple chromosomes, 80s ribosome (40s + 60s), wall of cellulose or chitin (simple)

Question 2

What are the various staining reactions? What reagents are used?

Answer 2

gram staining (crystal violet, iodine, acetone, safranin), acid fast (carbolfuschin, heat, acid/alcohol pulls from non-acid fast, add methylene blue), immunoflourescent (Ab labeled w/ fluorescence to a cell wall component), geimsa stain, silver impregnation

Question 3

What are the morphology of bacteria?

Answer 3

cocci (clusters, chain, diplococcic), bacilli (coccobacilli, vibrios, fusiform), spiral (spirochetes), and other (diptheroid, pleomorphic- clubbed, branched, filamentous, irregular, Chinese letters)

Question 4

What are the general features of a gram positive cell?

Answer 4

cell wall has teichoic acid on the outer surface (roll in virulence), has pili (fimbriae), possibly a singular flagella and a capsule

Question 5

What are the general features of a gram negative cell?

Answer 5

outer membrane with porins and adhesion sites, periplasmic space, inner membrane made of peptidoglycan (thinner for gram -)

Question 6

What are the properties of flagella?

Answer 6

main way B move, aka H Ag target for antibodies, virulence factor, used in serological ID, is a PAMP

Question 7

What are the properties of pili (fimbriae)?

Answer 7

attachment to tissues, virulence factor, anchored in membrane, sex pili (type IV secretion system) on gram -, antigenic variation to evade immune system, a PAMP

Question 8

What are the properties of capsule or slime layer?

Answer 8

virulence factor, allow adherence to each other, biofilms and artificial surfaces, polysaccharide, K Ag in many Vi Ag in salmonella

Question 9

What is a biofilm and what can it do?

Answer 9

plaque, increase gene transfer, increase antibiotic resistance, more virulent phenotypes, hard for antibiotic to get through, can be polymicrobial, can result in - blood cultures

Question 10

What are the bacterial PAMPs?

Answer 10

LPS, peptidoglycan, flagellin, porins, lipoteichoic acids, lipoproteins and other membrane/cell wall/cytoplasm components

Question 11

What is the make up of gram + cell wall organization?

Answer 11

polysaccharide chain linked by tetrapeptide chain and peptide cross bridge, teichoic acid and lipoteichoic acid anchored in wall and sticking out, pili, and cell wall specific Ag= peptidoglycan layer, cytoplasmic membrane under that made of phospholipids and proteins

Question 12

What is the structure of peptidoglycan?

Answer 12

aka murein, polysaccharide chain, tetrapeptide side chains, peptide cross bridges (target of transpeptidase, penicillin binding protein), biologic activities- inflammation, adhesion antiphagocytic, somnolence, PAMP

Question 13

What does teichoic acids cause in the host?

Answer 13

gram +, inflammation, adhesion, cation binding, biofilm formation, phage receptors, PAMPs

Question 14

What are some key components of the outer membrane of gram - bacteria?

Answer 14

porins (trimer, PAMP), secretion systems (type III and IV), LPS (endotoxin), periplasmic space, and peptidoglycan (murein, PAMP)

Question 15

How do the different secretion systems work?

Answer 15

III: syringe and needle, translocation of effector proteins (exotoxin) into eukaryotic cytoplasm (otherwise stuck in PP space); IV- conjugation, biofilm formation, adhesion

Question 16

What are the features of LPS on gram - outer membranes?

Answer 16

lipid A is toxic portion (virulence factor), polysaccharide core, repeat unit P-O-P= O Ag in serotyping also for adherence (virulence factor)

Question 17

What compounds are used to remove cell walls for different types of cells?

Answer 17

protoplasts (G+), Spheroblasts (G-), mycoplasma has no cell wall have to target protein synthesis

Question 18

What are the cytoplasmic membrane functions?

Answer 18

active transport, electron transport, synthesis and export of cell wall components, secretion of enzymes, including exotoxins

Question 19

What is an important factor in penicillin resistance in bacteria? is there a difference between Gram - and +?

Answer 19

periplasmic space allows for concentration of B-lactamase so more potent with Gram -, Gram + still secretes it but has to constantly produce it

Question 20

What are the typical cytoplasmic contents of bacteria?

Answer 20

chromosome: circular, plasmid- extrachromosomal DNA-> virulence factor or AB resistance, spreads btwn B and viruses, can have multiple copies; ribosomes: 70s (30s + 50s), and inclusions

Question 21

What is an endospore? Which type forms this?

Answer 21

protective function, gram positive, forms when nutrient levels drop so it can regerminate when there is a new nutrient source

Question 22

What are the components of a spore? (outside in with function or make-up)

Answer 22

Exosporim, Coat (protein with disulfide bond, most of resistance), Outer membrane, cortex (peptidoglycan), inner membrane, core (dehydrated with enzymes and chromosome)