Download Transport and Metabolism Group work

Stage 02 – Colonization and Infection: Our 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, and subvert the immune system (that’s Stage 03),
2. have the right environment, and
3. transport in the nutrients they need to harvest energy and make precursor metabolites
a. that will allow them to build amino acid, nucleotide, lipid, and carbohydrate subunits,
i. which will allow them to build protein, nucleic acid, lipid, and polysaccharide
macromolecules through the processes of
1. DNA Replication,
2. Transcription,
3. Translation, and
4. Enzyme-mediated chemical reactions
a. Which will allow them to make the cellular structures needed to produce
a new generation of cells.
To write the third part of this story, we must first follow nutrients, molecules, and ions as they are transported
across the cell membrane, broken down or used to harvest chemical energy, and used to make precursor
metabolites.
To do this we will follow:
1) how nutrients and other molecules and ions are transported across the cell membrane,
2) how energy is harvested by diverse prokaryotic metabolic reactions and stored as ATP, reducing power, and
the proton motive force,
3) what processes make precursor metabolites,
4) how enzymes regulate these processes.
1) Transport across the cell membrane:
With your group, draw a skeleton model of a typical bacterial cell and indicate how the membrane functions to
regulate nutrient transport, oxygen and carbon dioxide transport, and a hydrogen ion electrochemical gradient
across the cell membrane.
Be sure to include ALL of the following:
 A drawing of the plasma membrane and cell wall of a bacterial cell:
o Peptidoglycan layer (plus outer membrane for Gram negative cells)
o Phospholipid bilayer
o Transport channel proteins (plus porins in outer membrane for Gram negative cells)
 Drawing and accompanying explanation about how the process works indicates how the membrane
regulates
o Nutrient transport into the cell through
 Facilitated diffusion
 Active transport
• Driven by proton motive force
• Driven by ATP (ABC Transporters)
 Group Translocation
o Oxygen and carbon dioxide transport into and out of the cell through
 Simple diffusion
o Hydrogen ion electrochemical gradient (proton motive force) across the cell membrane through
 Electron transport chain
2) How energy is harvested and stored and how precursor metabolites are made (Focus on information in
sections 6.1-6.2 and 6.10):
In your group, organize the following key terms and processes to show their relationship inside different
chemoorganotrophic bacteria as they harvest and store energy from organic chemical energy sources and make
precursor metabolites.
A) First write a brief summary of the following catabolic processes (p132-134; Group quiz 4):
o The central metabolic pathways
 Glycolysis
 Pentose phosphate pathway
 Tricarboxylic acid cycle (TCA cycle)
o Aerobic respiration
o Anaerobic respiration
o Fermentation
B) Now for the different chemoorganotrophic bacteria. Organize a flow chart, a picture, or a diagram of
your group’s choosing that shows how energy is harvested by each of the following different types of
bacteria:
Obligate aerobe
Facultative anaerobe
Obligate anaerobe
Be sure to include the following information in your organization:
o The catabolic processes that you would find being used by these bacteria (summarized in
Part A).
o Note that enzymes are carrying out these metabolic reactions!
o How energy is stored during these processes
 ATP
• Substrate-level phosphorylation and/or
• Oxidative phosphorylation
 Proton motive force
• Electron transport chain
• Redox reactions
• Active transport
• Proton (H+) concentration gradient
 Reducing power
• Electron carriers
C) Now for the last part of catabolism, we need to understand that precursor metabolites are made
during these processes so that the bacteria can use them for growth (anabolism).
Go back to your work in Part B and using Figure 6.28 as a guide, label where the precursor
metabolites are generated to make the following subunits (you do NOT need to label the actual precursor
metabolites – just indicate which catabolic pathway(s) they are coming from:
o Note, once again, that enzymes are carrying out these metabolic reactions!
o amino acids (to make proteins)
o nucleotides (to make DNA or RNA)
o fatty acids (to make lipids)
o glycerol (to make lipids)
o monosaccharides (to make lipopolysaccharide or peptidoglycan)