bacterial properties and disease

Question 1

5 functions which bacterial pathogens must do

Answer 1

colonise, persist, replicate, disseminate within cells and hosts, cause disease

Question 2

3 structures of bacterium

Answer 2

cocci (spherical), bacilli (cuboidal rod), spirilli (long, spiral, wiggly)

Question 3

IC vs EC bacteria

Answer 3

EC do not invade cells and replicate outside; IC enter cell to replicate inside phago/endosome

Question 4

4 examples of IC bacteria

Answer 4

Shigella (dysentry), Salmonella (food poisoning/typhoid), M. tuberculosis, chlamydia

Question 5

4 examples of EC bacteria

Answer 5

S. aureus, S. pneumoniae, Yersinia, Neisseria (meningitis/gonorrhoea)

Question 6

2 types of IC bacteria

Answer 6

aerobic, anaerobic

Question 7

example of faculative (uses aerobic but can switch to anaerobic) IC bacteria

Answer 7

Shigella

Question 8

example of obligate (cannot switch between aerobic and anaerobic) IC bacteria

Answer 8

chlamydia

Question 9

gram +ve vs gram -ve

Answer 9

+ve: single membrane with large peptidoglycan layer on top that traps dye to appear purple; -ve: two membranes with thin peptidoglycan in-between so lose dye and appear pink

Question 10

define acid-fast bacterium

Answer 10

bacteria (particularly mycobacterium) that resist staining using an acid stain

Question 11

2 examples of gram +ve bacteria

Answer 11

S. aureus, S. pneumoniae

Question 12

5 examples of gram -ve bacteria

Answer 12

E. coli, Salmonella, Shigella, V. cholerae, Neisseria

Question 13

what makes up the majority of the outer membrane of gram -ve bacteria

Answer 13

LPS

Question 14

4 modern testing techniques for bacteria

Answer 14

culture and microscopy, biochem/serological tests, antibiotic sensitivity, DNA PCR/sequencing

Question 15

what do bacteria use to invade a host

Answer 15

using an injectisome (type III secretion system)

Question 16

explain how an injectisome allows a bacteria to invade a host

Answer 16

needle structure which pumps effector proteins into cell, causing actin polymerisation and membrane ruffling - tricks cell into making more actin, trapping the pathogen and bringing it into cell

Question 17

how do bacteria then move into other cells

Answer 17

break out of vacuole, polymerising actin at one pole to generate force to propel through cytoplasm, across 2 bacterial and 1 host cell membrane into another cell (“comet tails”)

Question 18

what allows movement in bacterium

Answer 18

flagellum - complex of rotating rings and filaments