Bacteriology

Question 1

describe the general process of recombinant bacteria insulin manufacture

Answer 1

isolate plasmid and human DNA
cut both DNA with same restriction enzymes
mix DNA - get recombinant and no recombinant plasmids
introduce the DNA into bacterial cells that have mutation in own lacZ gene

Question 2

two general ways bacteria cause disease

give a couple examples

Answer 2

disrupting the physiology of the cell by invasion and growth (leprosy, syphilis, typhoid fever)
growing inside the host and producing toxins (tetanus, botulism)

Question 3

how many bacterial cells does the human body contain

Answer 3

10^14

Question 4

what pathogens can resident E.coil in the gut kill

Answer 4

salmonella, shigella, clostridium (by producing compounds that kill them)

Question 5

what phylogenetic analysis is used to distinguish between bacterial species

Answer 5

16S rRNA analysis by PCR - gene amplified by the Sanger method

Question 6

why is the 16S rRNA sequence used to distinguish between dna

Answer 6

high copy number, variable and conserved regions, essential for life

Question 7

what are the two main types of bacteria

Answer 7

Gram positive - blue, thick layer of peptidoglycan

Gram negative - pink, thin layer of peptidoglycan

Question 8

what factors influence speciation in bacteria

Answer 8

• relatively fast generation times
• adaptive mutations
• horizontal gene transfer and the ‘core’ genome

Question 9

what are the 3 routes of horizontal gene transfer

Answer 9

1. transformation - naked DNA released by one cell and taken up by another
2. transduction- bacterial DNA begin transfer by virus, by phages
3. conjugation - cells join together and DNA can transfer from one to the other

Question 10

what is the pan genome

Answer 10

include the other mobile genetic elements, those coming in from outside

Question 11

what is the core genome

Answer 11

part of genome present in all strains of a species

Question 12

what are the agents of horizontal gene transfer

Answer 12

prophages and plasmids

Question 13

what are biofilms characterised by

3

Answer 13

irreversibly attached to a substratum interface or each other
are embedded in a self produced matrix of EPS
exhibit an altered phenotype (compared w planktonic cells) with respect to: growth rate and gene transcription

Question 14

what are the 6 stages of biofilm lifecycle

Answer 14

1. reversible adhesion
2. irreversible attachment
3. maturation
4. development
5. dispersion and sloughing off
6. transport of biofilm particles

Question 15

what components make up the EPS

Answer 15

biopolymers: polysaccharides, proteins, glycoproteins, phospholipids, nucleic acids

Question 16

what structures allow for irreversible adhesion/ polymer bridging
give 4 (of9)

Answer 16

exopolymers
fimbriae
flagella
stalks
lipoteichoic acids LTA
lipopolysaccharides LPS
s layers
a layers
surface localised proteins and pigments

Question 17

what are the three main functions of the cytoplasmic membrane

Answer 17

selective permeability
transport
energy conservation &consumption (proton motive force)

Question 18

what types of motility are exhibited by bacteria

Answer 18

Flagellar, Spirochaetal, Gliding

Question 19

bacterial flagella are around _____ thick and contain the protein ________

Answer 19

20nm thick and contain flagellin

Question 20

what six ways can bacteria move

Answer 20

swimming - rotating flagella
gliding - active surface movement involving focal adhesion complexes
twitching - jerk from attachment and detachment of type IV pili
swarming - multicellular surface movement by rotating helical flagella
sliding - passive surface translocation
darting -rapid motion

Question 21

what five ways can flagella be arranged on bacterium

Answer 21

Atrichous - no flagellum
Monotrichous - single flagellum
Lophotrichous - multiple flagella from the same location, forming a ‘tuft’
Amphitrichous - a single flagellum at each end
Peritrichous - numerous flagella around the cell (random array)

Question 22

what are the two main types of pili

Answer 22

conjugation pili

type IV pili

Question 23

describe the process of bacterial conjugation

Answer 23

1 donor cell produces pilus
2 pilus attaches to recipient cell, brings two cells together
3 the mobile plasmid is nicked and a single strand of DNA is then transferred to the recipient cell
4 both cells recircularise their plasmids, synthesise second strands and reproduce pili: both are now viable donors