Domain Bacteria- Lecture 4

What is the structure of Peptidoglycan?

• It has a sugar backbone (alternating modified glucose)

• N-acetylglucosamine (NAG) and N-acetylmuramuc (NAM) acid joined by beta 1,4 linkages

What is the peptidoglycan structures in the cell wall?

PG strands run parallel around cell circumference, cross-linked by covalent peptide bonds

What are the structure and activity of bacterial lipopolysaccharides (LPS)?

1. O-specific polysaccharide (aka o-antigen)- species specific

2. Core polysaccharide

3. Lipid A- endotoxin: the toxic component of LPS

What is twitching motility?

• The typical movement away from colony

• Slower than swimming

• requires type IV pili

What is gliding motility?

• Typically movement away from colony

• Slower than swimming

• Requires: intracellular proteins for track, motor, and adhesion

• Smooth, continuos motion along axis without external structures

What is taxis?

directed movements enhancing acess to resources or allows avoidance of damage/death

What is chemotaxis

response to chemicals

define phototaxis

response to light

define osmotaxis

response to ionic strength

define hydrotaxis

response to water

define aerotaxis

response to oxygen

What genus of bacteria have endospores?

1. Clostridium, Clostridioides

2. Bacillus

When are endospores produced? What do they do?

• produced when growth conditions are poor

• Aid in survival and dispersal

• Can be stained with endospore stain

• Very difficult to destroy (most effective treatment is autoclaving or sporicides such as bleach

What is sporulation

the process of forming an endospore

What is the difference between endospores and vegetative cells (this is a table to memorize)