Lecture 1 (17)-classification and ID

Question 1

how are bacteria classified

Answer 1

via nutrition, looks, surface molecules, end pdt

Question 2

Lipoarabinomannan

Answer 2

related to LPS that activate the immune system and are on acid fast bacteria

Question 3

arabinogalactans

Answer 3

polysaccardides in acid fast bacteria that allow mycolic acid to bind LPS

Question 4

mycolic acid

Answer 4

in acid fast bacteria, fatty acid that causes a waxy film over the LPS and makes it difficult to kill bacteria but also makes the bacteria slow-growing

Question 5

how does LPS cause inflammation

Answer 5

binds CD14/TLR4 on phagocytes/antigen presenting cells and causes immune response that can lead to septic shock

Question 6

components of LPS

Answer 6

Lipid A- virulent portion of the bacteria
core polysaccharide- maintains structure of bacteria
antigen O- variable polysaccharide that causes us to classify bacteria

Question 7

gram neg vs gram pos

Answer 7

neg- has outer membrane, thinner envelope due to less peptidoglycan, outer membrane with LPS and porins
pos- teichoic acid, thick peptidoglycan envelope with lots of crosslinkers, no outer membrane (thus NO LPS)

Question 8

features of outer membrane

Answer 8

porins- allow passage of only small molec
maintains structure
contains and tx secretory proteins
asymmetric phospholipid bilayer caused by LPS

Question 9

teichoic acid

Answer 9

only in gram pos bacteria
promote attachment of other bacteria and host cells
virulent factor

Question 10

what is peptidoglycan made up of

Answer 10

NAM and NAG plus peptide crosslinker

Question 11

layers of a gram neg bacteria

Answer 11

outer membrane with LPS, peptidoglycan, periplasmic space, plasma membrane

Question 12

what does peptidoglycan do?

Answer 12

its the internal capsule that provides structure to bacteria, protection, it’s what stains pos or neg, uniquely on bacteria

Question 13

pili/fimbrae

Answer 13

• have pilin that are small protein subunits that form hollow tubes
• allow for attachment to endothelial cells and used by both gram neg and gram pos bacteria
• 2 types- common or somatic
• involved in gene tx via plasmid thru the hollow tube to other bacteria

Question 14

Flagella

Answer 14

allow for locomotion of bacteria
on plasma membrane
have H antigen
important virulence factor-if remove flagella, hard for bacteria to cause disease

Question 15

capsule

Answer 15

• loose polysac/protein layer surrounding some gram pos or neg bacteria- called slime layer is nonuniform or loosely adherent
• aids in protection from immune system and is ANTIPHAGOCYTIC
• major virulent factor
• bacteria can grow without them but cant survive in the post without them
• serve as antigen for vaccines

Question 16

biofilm

Answer 16

a community of microbial cells that has a capsule over everything

Question 17

Quellung reaction

Answer 17

capsule visibly swells when anticapsular antibody used- therefore detects capsulated bacteria

Question 18

how are capsulated bacteria cleared by the immune system

Answer 18

via the spleen therefore people with splenectomies have probs

Question 19

endospores
what type of bacteria
what does it do?
what’s it like?

Answer 19

• occurs with some gram pos bacteria
• bacteria converted to a dormant state when conditions rough
• when conditions better, give rise to ONE bacteria- location in cell is a give-away for identification of bacteria
• dehydrated
• little amt of proteins/ribosomes, hi Ca2+ bound to dipocolinic acid
• super resilient-hi temp, pH, radiation, enzyme attack and chemical
• prob-bioterrorism
• lasts centuries
• can exist on medical equipment-autoclave at 120C and hi pressure >20min

Question 20

in terms of nuclei, how are bacteria and fungi different?

Answer 20

• bacteria are prokaryotes so do not have nuclei

- fungi are eukaryotes so they do have nuclei

Question 21

acid fast bacteria have peptidoglycan?

Answer 21

yes

Question 22

what type of bacteria has endotoxin?

Answer 22

endotoxin is LPS so only gram negative bacteria have it

Question 23

what virulence factor prevents phagocytosis?

Answer 23

capsule