GOAL: A great diversity of metabolic and biochemical are seen among the Bacteria, Archaea, and Eukarya yet some common metabolic pathways exist across all domains. OBJECTIVES OUTCOMES FORMATIVE ASSESSMENT SUMMATIVE ASSESSMENT Students will be able to identify the sources of energy used by different prokaryotes (i.e. chemotrophs vs. phototrophs) Brainstorm: what do we remember about how organisms acquire carbon and energy? PLANT? ANIMAL? FUNGI? Where do plants/animals acquire carbon for synthesis of organic compounds? energy for metabolic? 2. 3. 4. (A) (B) (C) (D) photolithoautotrophs photoorganoheterotrophs chemolithoautotrophs chemoorganoheterotrophs The cyanobacteria (and their close relatives the chloroplasts) carry out oxygenic photosynthesis. Thiomicrospira crunogena were discovered in the hydrothermal vents where they oxidize iron at high temperatures and pressures and use the energy from that process to produce organic compounds. Chloroflexus aurantiacus, a green non-sulfur bacterium, can absorb light energy for the production of ATP but must still obtain small organic molecules like acetate from the environment for anabolic. Describe the major nutritional types seen among the prokaryotes (i.e. chemoheterotrophs, chemoautotrophs, photoheterotrophs, photoautotrophs) Define auto/heterotroph Define photo/chemotroph Compare/contrast aerobic/anaerobic Compare/contrast anaerobic/fermentation 5. Organisms that use inorganic compounds like elemental iron, sulfur, or carbon dioxide as their reduced electron donor are referred to as (A) organotrophs (B) lithotrophs (C) autotrophs (D) heterotrophs Students will be able to identify the sources of carbon used by different prokaryotes (i.e. autotrophs vs. heterotrophs) Clicker questions: ID nutritional type of specific organisms based on descriptions of metabolism Post lecture questions on nutritional types using examples of specific organisms, particularly those that can change their nutritional type
Compare and contrast different respiratory in prokaryotes and eukaryotes the difference between aerobic and anaerobic respiration the difference between fermentation and anaerobic respiration describe how differences in the electron transport can lead to differences in net energy production Brainstorm: Generalized diagrams of respiratory process used to elicit discussion on differences/ similarities of respiration in various organisms. Identify components of anaerobic respiration Define electron transport chain Identify anabolic and catabolic Pair/share: given a final electron acceptor for one unusual microbe, speculate on oxidized respiratory product Quiz questions on respiration/fermentation 1. Which of the following is the best definition for fermentation? (A) a process where an energy source is oxidized and degraded with the use of oxygen as an exogenous electron acceptor (B) a process where an energy source is oxidized and degraded with the use of a molecule other than oxygen as an exogenous electron acceptor (C) a process where an energy source is oxidized and degraded with the use of oxygen as an engodenous electron acceptor (D) a process where an energy source is oxidized and degraded with the use of a molecule other than oxygen as an endogenous electron acceptor 2. The oxidase-negative bacteria Enterobacter aerogenes produces fewer ATP per NADH than the oxidase-positive Pseudomonas aeruginosa because (A) it has a shorter electron transport chain (B) it has a longer electron transport chain (C) it has a branched electron transport chain (D) it lacks an electron transport chain 3. Bradyrhizobium japonicum possesses the genes for nitrate reductase which allows it to use nitrate as a final electron acceptor. This process is best described as (A) assimilatory nitrate reduction involved with aerobic respiration (B) assimilatory nitrate reduction involved with anaerobic respiration (C) dissimilatory nitrate reduction involved with aerobic respiration (D) dissimilatory nitrate reduction involved with anaerobic respiration 4. When several electron acceptors are present in the environment, microorganisms will use these acceptors in succession starting with the electron acceptor with the most positive reduction potential, (A) nitrate (B) oxygen (C) carbon dioxide (D) sulfate 5. Several members of the Clostridium sp. are capable of performing a unique fermentation called the Strickland reaction which involves the fermentation of (A) polysaccharides (B) amino acids (C) fatty acids (D) glycerol 6. Heterolactic fermentation result in the formation of fermentation products which include (A) butanediol, only (B) lactic acid, only (C) ethyl alcohol, only (D) lactic and a mixture of other products
how electron transport chains function not only in catabolic like respiration but also in autotrophic Brainstorm: Generalized diagrams of autotrophic used to elicit discussion on differences/ similarities of autotrophy in various organisms. 1. The energy source which provides the electrons for this electron transport chain is (A) the ferrous ion, an exogenous electron donor (B) NADH, an exogenous electron donor (C) oxygen, an endogenous electron donor (D) the ferrous ion, an endogenous electron donor Compare and contrast different types of autotrophy seen in prokaryotes and eukaryotes differentiate between the chemoautotrophy and photoautotrophy with regard to the source of electrons used in each process. the role of oxygen in oxygenic photosynthesis and the difference between oxygenic and anoxygenic photosynthesis. differentiate between various types of carbon fixation. Compare/contrast light & dark reactions Define photosystem I/II Compare/contrast cyclic/noncyclic photophosphorylation Clicker questions: ID type of photosynthesis for specific organisms based on descriptions of metabolism, nutrients, light Quiz question on photosynthesis 2. The NADPH generated in this reaction is used (A) as a carbon source (B) as a source of protons for carbon fixation (C) as an energy source (D) as a cellular waste product 3. The electron transport chain shown here is involved in (A) chemolithoautotrophy (B) photolithoautotrophy (C) chemoorganoheterotrophy (D) photoorganoheterotrophy 1. Anoxygenic photosynthesizers differ from oxygenic photosynthesizers because anoxygenic photosynthesizers (A) always use both photosystems during photosynthesis (B) split water molecules to obtain the protons needed for carbon fixation (C) produce oxygen as a byproduct (D) are likely to use elemental hydrogen or H2S as a proton source 2. Unlike noncyclic photosynthesis, cyclic photosynthesis involves the production of (A) NADPH and oxygen (B) NADPH, oxygen, and ATP (C) oxygen and ATP (D) ATP, only 3. Rhodopsin-based phototrophy is different from chlorophyll-based phototrophy because in rhodopsin-based systems (A) the same molecule absorbs light energy and serves as an electron transport chain (B) the pigment used is bacteriochlorophyll instead of chlorophyll (C) the same molecule absorbs light energy and produces organic compounds (D) none of the above 4. All of the following are carbon fixation pathways found in bacteria EXCEPT (A) the Ljungdahl-Wood pathway (B) the Calvin-Benson cycle (C) the reductive TCA cycle (D) the Entner-Douderoff Pathway
Explain central metabolism Students will be able to explain the role of central metabolism and the difference between central metabolism and other metabolic Students will be able to discuss how central metabolism shows the evolutionary relationship between organisms in all three domains of life. Identify anabolic and catabolic pp. LEARNING ACTIVITY DISCUSSION: Evolutionary changes that have resulted in new metabolic pathways (i.e. how do all of the additional pathways that we have discussed collect to central metabolism) 1. All of the following are considered parts of central metabolism EXCEPT (A) C, D, and E (B) D only (C) E only (D) D and E (2) Sometimes the evolution of complex metabolic systems is accomplished by changes in only one or two enzymes. These changes create whole new metabolic process from preexisting ones. Explain how one of the following is believed to have evolved, noting the preexisting pathway it evolved from and the changes necessary to create the new pathway: a) TCA cycle (also known as the Kreb s or citric acid cycle) b) Calvin-Benson cycle Understand the role of central metabolism in anabolic as well as catabolic describe the relationships between central metabolism and both catabolic and biosynthetic pathways Questions asking students questions about how various metabolic connect to central metabolism 1. The chemical reaction shown here is best described as (A) deamination (B) transamination (C) decarboxylation (D) transcarboxylation 2. Assimilatory nitrate reduction is essential in many bacteria for (A) the production of amino acids (B) anaerobic respiration (C) chemolithotrophy (D) the production of fatty acids 3. Sometimes the reactions of central metabolism are so much more important for biosynthesis than for catabolism that special pathways exist to ensure that precursor molecules will always be available. These special pathways are called (A) anapleurotic (B) anabolic (C) anammoxisomic (D) endergonic Apply an overall understanding of prokaryotic metabolic to current research in the field. Boyd ES, Schut GJ, Adams MWW, Peters JW. 2014. Hydrogen Metabolism and the Evolution of Biological Respiration. Microbe 9(9): 361-367. 1. According to the paper of Boyd, et al., membrane-bound hydrogenases likely formed complexes with proteins that translocated ions across membranes. The hydrogenase pathways are believed to be the ancestors of the modern (A) electron transport chains (B) Kreb s cycle (C) Calvin-Benson cycle
PRE-CLASS ASSIGMENT (D) Emden-Meyerhoff pathway Assign article as reading with guided questions Groups discuss guided questions before class discussion of article. Post discussion of article, back in groups to discuss how article demonstrate evolution of electron transport chains. 2. The Fe-Fe hydrogenases are found in a limited number of strict anaerobic bacteria and a few unicellular eukaryotes but not the archaea, while Ni-Fe hydrogenases are widely distributed in the archaeal and bacterial domains. For this reason, evolutionary biologists believe that (A) Fe-Fe hydrogenases evolved before the divergence of bacteria and (B) Ni-Fe hydrogenases evolved before the divergence of bacteria and (C) both hydrogenases evolved before the divergence of bacteria and (D) both hydrogenases evolved after the divergence of bacteria and 3. The reduction of microbial populations to a safe level as determined by public health standards is known as (A) antisepsis (B) disinfection (C) de-germing (D) sanitation Note: This is the metabolism section for a 300-level microbiology course to mainly to second semester, senior biology majors who have had 7 semesters of bio and 20 credits of chem. I have always tried to build of the knowledge about metabolism that I know was covered in General Biology and that has been reinforced in several other upper level classes. It has become apparent that not all students remember this information in quite the way I think they do and that it will be necessary to have them unpack this information in a way that they can effectively move on to a discussion of the far more complicated and diverse metabolism of microbes. Summative assessment questions shown here are from exams I rewrote this past semester. While many seemed to line up reasonably well with the learning objectives and outcomes, it quickly became apparent that I was missing any formative pieces. I now believe that effective formative assessments will be necessary to get students of effectively review the information they already know about metabolism