2.3 Bacteria

Question 1

Bacteria are…

Answer 1

Unicellular prokaryotes that divide by budding

Question 2

Bacteria enter hosts…

Answer 2

Through preexisting openings, they cannot create infection structures

Question 3

Bacteria are mobile via…

Answer 3

Flagellae

Question 4

Bacteria can form…

Answer 4

A biofilm which immobilises them

Question 5

Bacterial symptoms

Answer 5

1. Rot: cell wall degradation, water soaked, slimy
2. Wilting, dry necrosis nearby veins, dehydration
3. Chlorosis (yellowing) of leaf or fruit tissue

Question 6

Quorum Sensing

Answer 6

Bacteria initiate attack only when high cell density is reached

Density measured by a small signal molecule (AHL)

High [AHL] induces transcription of genes required for infection

Question 7

Processes regulated by Quorum Sensing

Answer 7

1. Production of plant cell wall degrading enzymes which
   destroy host cell walls and allow invasion
2. Production of toxins that cause plant chlorosis and
   necrosis
3. Production of antibiotics
4. Formation of biofilm

Question 8

Quorum Quenching

Answer 8

Interfering with quantum sensing to design plant protection strategies

Question 9

Main points

Answer 9

Plant pathogenic bacteria:

• Can cause different types
of symptoms

• Need to build a community
before attacking

• Use Quorum Sensing to
monitor cell density and
regulate gene expression

• Quorum Quenching can
reduce damage by bacteria