Medical Micro - Bacteriology

Question 1

what are the 2 types of bacterial cells

Answer 1

gram +
gram -

Question 2

difference between bacteria and archaea

Answer 2

lack peptidoglycan in cell walls
mostly studied in extreme environments
have different types of lipids in their membrane

Question 3

features of crenarchaetoa and where do they reside

Answer 3

Thermophilic & hyperthermophilic.
Cool marine planktonic waters

Question 4

features of euryarchaetoa

Answer 4

methanogens
Halophiles
Thermoacidophiles

Question 5

what do methanogens do

Answer 5

use H2 to reduce CO2 to CH4

Question 6

where do halophiles reside

Answer 6

Halophiles – live in very high salt environments

Question 7

what are optimum conditions for thermacidophiles

Answer 7

have an optimum growth temperature between 60 – 80C
live at low pH

Question 8

what are protozoans

Answer 8

protista
eukaryotic cell

Question 9

where do protozoans inhabit and what do they consume

Answer 9

water and soil
feed on bacteria and small particles

Question 10

how do protozoans reproduce

Answer 10

sexually and asexually

Question 11

how do protozoans consume their food

Answer 11

absorb nutrients through their membrane or wrap themselves around their prey to ingest

Question 12

what is the size range of a protozoan

Answer 12

2μm - 2mm

Question 13

what is a virus

Answer 13

Obligate intracellular parasites – cannot replicate by themselves

Question 14

what kingdom do virus belong to

Answer 14

no kingdom

Question 15

how is information organised within a virus

Answer 15

ds DNA, ss DNA, ds RNA, ss RNA – usually organised as single linear or circular molecule of nucleic acid.

Question 16

structure and function of the caspid

Answer 16

protein subunits
protects the nucleic acids

Question 17

what is marine snow

Answer 17

loose association of microbes with organic detritus

Question 18

what are pellicles

Answer 18

predominantly 2D structures forming on surface of liquids

Question 19

what is step 1and 2 of biofilm formation

Answer 19

adhesion
reversible and irreversible

Question 20

what is step 3 of biofilm formation

Answer 20

maturation 1
formation of microcolonies surrounded by EPS

Question 21

what is step 4 of biofilm maturation

Answer 21

maturation 2
formation of a continuous biofilm

Question 22

what is step 5 of biofilm formation

Answer 22

dispersion and sloughing off
due to programmed cell death, lytic phage expression or NO signalling

Question 23

what is step 6 of biofilm formation

Answer 23

transport of biofilm particles
dispersed organisms phenotypically similar to planktonic cells

Question 24

what is EPS

Answer 24

extracellular polymeric substance
house of biofilm

Question 25

list biopolymers of microbial origins

Answer 25

polysaccharides proteins glycolipids, phospholipids, LPS nucleic acids

Question 26

what does bacterial biofilm act as

Answer 26

a major barrier to wound healing

Question 27

outline initial reversible adhesion

Answer 27

adhesion at a distance of 5-20nm little energy needed to remove bacteria

Question 28

outline irreversible adhesion

Answer 28

binding is mediated by polymer bridging - achieved by reduced radius of body irreversible binding specific receptor/adhesion process achieved by bacteria but not colloids

Question 29

outline the structural function of peptidoglycan

Answer 29

forms sheets around the cell - connected by cross links to form a polymer can be 90% of gram-positive cell wall

Question 30

in gram-negative bacteria what is used as an effective bacteria

Answer 30

lipopolysaccharide layer LPS

Question 31

what is the purpose of understanding the differences of gram-negative/positive cell walls

Answer 31

important for targeting bacteria many antibiotics are effective in targeting gram-positive bacteria but show little specificity for gram-negative bacteria

Question 32

in terms of microbial locomotion what is the purpose of gas vesicles

Answer 32

allow regulation of position in water column for some aquatic species

Question 33

what are some forms of bacterial motility except flagella

Answer 33

twitching gliding swarming

Question 34

what are the 3 main morphologies of dsDNA phages

Answer 34

myophage siphophage podophage

Question 35

what allows phages to have different specificity

Answer 35

absorption apparatus

Question 36

what is rigid body motion

Answer 36

rotation of the phage that allows it to inject genetic material into the host

Question 37

what is reversible absorption

Answer 37

first contact of the phage with the receptor on the cell surface

Question 38

what is irreversible absorbtion

Answer 38

phage walks on the cell surface to find a spot to absorb irreversibly AKA moon walk

Question 39

how does long flexible ejection system work

Answer 39

the phage uses a screw like mechanism that reaches the host cytoplasm

Question 40

how does viral contractile ejection system work

Answer 40

the phage docks and ejects genetic material into the host cytoplasm

Question 41

what is the difference between lytic and lysogenic phages

Answer 41

lytic - replicates phages and kills cell temperate - introduces viral genetic material into host genome

Question 42

functions of endolysins/holins step 0

Answer 42

lytic protein accumulation

Question 43

step 1 of endolysins/holins function

Answer 43

inner membrane disruption

Question 44

step 2 of endolysins/holins function

Answer 44

peptidoglycan disruption

Question 45

step 3 of endolysins/holins function

Answer 45

outer membrane fusion with inner membrane

Question 46

what is the lysogenic cycle

Answer 46

phage inserts its viral genetic material into host genome does not kill the host - initially

Question 47

how do temperate phages decide between lytic or lysogenic

Answer 47

lysogenic - low amount of host compared to phages lytic - abundance of hosts to infect phages communicate to each other to decide

Question 48

what is the pseudo-lysogenic cycle

Answer 48

phage infects a cell that does not want to divide phage remains in the cell as a molecule only one of the daughter cells carries phage DNA

Question 49

step 1 for capsid formation in the cell

Answer 49

terminase binds viral genome

Question 50

step 2 of capsid formation in the cell

Answer 50

terminase-DNA binds procapsid portal

Question 51

step 3 of capsid formation in the cell

Answer 51

DNA translocation

Question 52

step 4 of capsid formation in the cell

Answer 52

contamer cleavage and packaging completion

Question 53

what are different antiviral resistance methods

Answer 53

preventing virus absorption preventing virus DNA entry cutting virus nucleic acids abortive infections

Question 54

how is virus absorption blocked

Answer 54

the host can mutate or mask its receptors phage cannot undergo irreversible binding

Question 55

how do phages bypass receptor masking by EPS

Answer 55

phages produce EPS degrading enzymes

Question 56

what is superinfection exclusion

Answer 56

when a virus infects a host cell and commands the cell to not allow other viruses to enter

Question 57

how is superinfection exclusion mechanism achieved

Answer 57

expression of: Imm - redirects DNA outsides Sp - blocks T4 lysosome

Question 58

how is cutting virus nucleic acids mechanism acheived

Answer 58

host DNA is protected from cleavage, viral DNA is not i.e. methylation

Question 59

how can phages bypass virus nucleic acid cleavage

Answer 59

modify nucleotides, makes it bulkier enzymes cannot reach nucleic acids to cleave it

Question 60

how is the abortive infection mechanism achieved

Answer 60

Phage DNA replication is detected by RexA activated RexA activates RexB RexB allows escape of +ions membrane potential is lost and ATP synthesis is blocked