Adaptation And Response

Question 1

Bact with 2 chromosomes

Answer 1

Brucella

Vibrio

Question 2

Bact with linear chrom

Answer 2

Bordetella

Question 3

Genes on bact chrom encode for

Answer 3

Factors req for metabolism
Produce virulence factors
(Virulence determinant genes)

Question 4

Normal bact chrom appearance

Answer 4

Single circular not enclosed by mem.

Tightly packed in supercoiled state when not repl ir transcribed

Question 5

Smallest bact chrom

Answer 5

Mycoplasmas approx 1Mb

Question 6

Larger bact genome

Answer 6

Salm typh
Mycobact bovis both approx 4.5Mb
Burkholderia cepacia approx 9Mb

Question 7

Intermediate chrom size

Answer 7

Staph and strep approx 2.5 Mb

Question 8

Larger genome size allow

Answer 8

More complex lifestyle and/or produce more complex structures eg mycobact CW which req more genetic info

Question 9

Smaller genome size mean

Answer 9

Must rely on many host cell fxs

Question 10

What allows variation between chromosome size and sequence even within a species?

Answer 10

Mosaic nature of chromosome with large ‘islands’ that arise from bacteriophage integration or uptake and integration of other bact DNA

Question 11

Pathogenicity islands

Answer 11

Islands encoding numerous virulence-associated factors

Question 12

What allows easier IDing of aquired regions following sequencing

Answer 12

Altered DNA content especially G/C ratio

Question 13

Plasmids

Answer 13

Circulat DNA elements 5-100 genes
Replicate autonomously
Products can be important in bact disease eg those encoding virulence factors and antibio res

Question 14

Potential Phage infection advantages

Answer 14

Phage may carry genes from other bact that confer growth advantage to current host bact. Esp of the genes integrate into the bact chrom
Some are known to carry viruence factors - many toxins transferred via phages
Most pathogenecity islands probably moved between bact by phages

Question 15

What is success of bact a conseq of

Answer 15

Their capacity to adapt and respond to change

Question 16

How do they gen variation to survive

Answer 16

By changes made to DNA eg mutations that can be selected for or against (adaptation)
And by having regulation that allows a variety of responses to one stimuli (regulation)

Question 17

Adaptive genetic changes include

Answer 17

Point mutation (silent/missense/nonsense substitutions)
Deletion/insertion (frame shift)
Inversion, duplication (rearrangement)
Acquisition of new genetic material

Question 18

Genome alterations induced by

Answer 18

Chem reagents
UV radiation
EC genomic elements

Question 19

Mechanisms to acquire foreign genes

Answer 19

Transformation
Conjugation
Transduction

Question 20

Transformation

Answer 20

Uptake of naked EC DNA that may be incorporated into the chrom by recombination or replic independently eg plasmid
Most DNA digested by endonucleases a D against bacteriophages

Question 21

Conjugation

Answer 21

Some plasmids encode transfer factors which direct conjugation. Filamentous pili prod by donor which adhere to recipient plasmid is duplicated and one strand is transferred via pili to recipient (many antibio res plasmids are conjugative)

Question 22

Transduction

Answer 22

Process of bact genome transfer via phages

Question 23

Generalised transduction

Answer 23

Phages randomly acquire and transfer bact genomic sequences

Question 24

Specialised transduction

Answer 24

Integration (lysogeny) of phage into bact chrom after which adjacent bact sequences to integration site may be packeted by phage to transfer to new host bact following phage induced bact lysis

Question 25

How can phage sequence become permanent feature in that bact strain

Answer 25

If mutation occurs in key phage replic genes integrated into bact genome but infection by another active phage could rescue defective phage

Question 26

What drives phage and host bact evolution

Answer 26

Mixing of genetic info between phages to generate multiple variants

Question 27

What level does regulation occur at

Answer 27

Transcription
Translational
Post-translational

Question 28

Sensing mechanisms of bact

Answer 28

Activation or repression of gene dep on availability of nutrients
Component signal transduction systems
Quorum sensing

Question 29

Act/repr of gene sensing mech Fe eg

Answer 29

Fe needed for bact growth so levels closely monitored - low level cause expression of factors to obtain Fe from host (some kill host cell)

Question 30

How bact sense that they’re in a spec niche

Answer 30

Ion, carbon, nitrogen, O2 tension and temp etc montioring

Question 31

Component signal transduction

Answer 31

Pass info through bact cell wall and mem following external factor detection.

Question 32

How is signal in component signal transduction passed

Answer 32

By a phopho-relay system leading to changes in the activity of a DNA binding pro either act or repr certain genes

Question 33

Quorum sensing

Answer 33

Capacity of bact to monitor particular compounds released by other bact and alter gene expression based on bact cell density.

Question 34

Quorum sensing uses

Answer 34

When high bact numbers needed to break through barrier

Signal bact presence in spec enviro eg large intestine of GIT cont large no of bact

Question 35

Molecular koch’s postulates measure

Answer 35

Interrogate Significance of bact genes (suspected as being key in virulence/infection) in the dis process

Question 36

Molecular koch’s pistukates

Answer 36

Phenotype/genotype investigated should be assoc with pathogenic members of a genus
Spec inact of gene/s assoc with suspected virulence trait should cause measurable pathogenicity/virulence loss
Reversion/allelic replacement of mutated gene should cause restoration of pathogenicity (complementation)

Question 37

New pacifying method to treat infection

Answer 37

Compounds that combat the expr or act of virulence factors, pacifying pathogen and aiding natural hist D removal