Download Adhesion environment nutrients

Bio260 – Spring 2014
North Seattle College
Stage 02 – Colonization and Infection
This explanatory model will tell the story of how one bacterium adheres to a host and, through binary fission,
ends up making two daughter cells. You should know how to explain this story:
For prokaryotic cells to grow by binary fission in order to colonize or infect a host they need to
1. adhere to the host, get past the normal microbiota,
2. have the right environment,
3. transport in necessary nutrients,
4. harvest energy and make precursor metabolites from those nutrients
that will allow them to build amino acid, nucleotide, lipid, and carbohydrate subunits
5. use those subunits to build macromolecules (proteins, nucleic acids, lipids, and polysaccharides) through
the processes of
• DNA Replication
• Transcription
• Translation, and
• Enzyme-mediated chemical reactions
6. and, finally, make cellular structures with those macromolecules in order to produce a whole new cell
by binary fission.
1. ADHERE AND DEFEND: Our bacterium has entered the host. Now it needs to adhere and get past the
normal microbiota.
 Adhesins on the bacterial cell
o Pili (fimbriae)
o Cell wall proteins
o Capsule surface structures
 Receptor on the host cell
o Highly-specific adhesin-receptor binding
 Normal microbiota
o Binding sites
o Nutrients
o Toxic products
2. ENVIRONMENT: Our bacterium also needs the right environment to grow.
 Temperature
o a graph showing the temperature ranges for (Figure 4.8)
 psychrophiles
 psychrotrophs
 mesophiles
 thermophiles
 hyperthermophiles
o protein structure
 draw a protein with tertiary structure
• amino acids
• alpha-helix
• beta-pleated sheet
• hydrogen bonds
 explain what would happen to that structure if the temperature were too high
• denaturation
 Oxygen (O2) Availability (Table 4.3)
o Energy-harvesting mechanisms (short description of each)
 Obligate aerobe
 Facultative anaerobe
 Obligate anaerobe
 Microaerophile
 Aerotolerant anaerobe (obligate fermenter)
o Reactive oxygen species
 Damage cell components
• Superoxide (O2-)
• Hydrogen peroxide (H2O2)
 Inactivation by
• Superoxide dismutase
• Catalase
 pH
o Neutrophiles
o Acidophiles
o Alkaliphiles
 Water availability
o Important cell structures:
 Cell wall
 Cytoplasmic membrane
o Draw/explain what would happen to a bacterial cell in
 A hypotonic environment
 A hypertonic environment
• Plasmolysis
3. TRANSPORT NUTRIENTS: Now that our bacterium has successfully attached, fought off the normal
microbiota, and finds itself in the right environment, let’s find out what nutrients it needs to grow and how the
cell transports them inside.
 Nutrients
o Certain elements are required for cell growth: Redraw Table 4.4
o Growth factors
GO TO TRANSPORT WORKSHEET