Chapter 7A - Microbial Metabolism: Fermentation & Respiration Flashcards
What does “-troph” mean?
Nourish
In Greek, -trophos means one who ______________.
Nourishes
Microbiologists conventionally divide microbes into categories based on their preferred ________________ source (organic or carbon dioxide) and ________________ source (chemical compounds or light).
Carbon
Energy
Chemotrophs use chemical compounds as their ________________ source; ________________ use light. Autotrophs use ________________ ________________ as their carbon source; ___________________ use organic compounds.
Energy
Phototrophs
Carbon dioxide
Heterotrophs
What is a chemotroph?
An organism that uses organiccompounds as energy sources
What is a chemoorganotroph?
A chemotroph that also uses organic compounds to attain carbon molecules for cellular function
What is a chemolithotroph?
An organism that is able to use inorganic reduced compounds as a source of energy
What is a phototroph?
An organism that uses light as an energy source
What is an autotroph?
An organism that uses carbon dioxide as a carbon source
What is a heterotroph?
An organism that uses organic compounds as a carbon source
There are four nutrition categories under which microbes can be divided. What are they?
(1) Chemoheterotrophs (2) Chemoautotrophs (3) Photoautotrophs (4) Photoheterotrophs
Into which nutrition category do most microbes fall?
Chemoheterotrophs
Chemoheterotrophs use _________________ _________________ _________________ as their energy sources and organic carbon as their carbon sources.
Oxidized chemical compounds
Chemoautotrophs use _________________ _________________ _________________ _________________ as their energy sources and _____________ _____________ as their carbon source.
Oxidized inorganic chemical compounds Carbon dioxide
Photoautotrophs use ______________ as their energy source and _______________ _______________ as their carbon source.
Light Carbon dioxide
Into which category of nutrient metabolism do bacteria and eukarya that contain chloroplasts fall?
Photoautotrophs
Photoheterotrophs use _______________ as their energy source and _______________ _______________ as their carbon sources.
Light
Organic compounds
Microbial metabolism can be based upon source of nutrition and relationship to what molecule?
Oxygen
_________________ are organisms that have adapted to growth in the presence of air, which is approximately 20% oxygen.
Aerobes
__________________ are organisms that have no or reduced protective mechanisms against the toxic effects of oxygen and therefore live in habitats from which oxygen is excluded.
Anaerobes
What are three types of aerobic metabolism?
- Aerobic respiration
- Oxygenic photosynthesis
- Anoxygenic photosynthesis
What are three types of anaerobic metabolism?
- Fermentation
- Anaerobic respiration
- Anoxygenic photosynthesis
What is anoxygenic photosynthesis?
A type of photosynthesis in which the final electron donor is something other than water and no oxygen is produced
“Anoxygenic” literally means…?
Without oxygen produced/caused by/related to a gene
What is oxygenic photosynthesis?
A type of photosynthesis in which water is used as an electron donor and produces oxygen
What does respiration mean?
A process in living organisms involving the production of energy from the oxidation of complex organic substances
__________________________ refers to the oxidation of a compound with a terminal electron acceptor that is usually accompanied with ATP synthesis via oxidative phosphorylation
Respiration
___________________ refers to catabolic reactions producing ATP in which organic compounds serve as primary electron donors and ultimate electron acceptors; ATP is produced via substrate-level phosophorylation, and they is no need for external electron acceptors.
Fermentation
Is glycolysis considered fermentation?
Yes, technically it is fermentation
Can microbes switch from one category of metabolism to another?
Yes, depending upon environmental conditions
What term is used to designate organisms that can use two or more modes of metabolism?
Facultative
What term means the opposite of facultative?
Obligate
Many ___________________________ use aerobic respiration in the presence of oxygen and fermentation or anaerobic respiration when oxygen is absent.
Chemoheterotrophs
Some bacteria can grow anaerobically in light, using ___________________ _____________________, or aerobically as chemoheterotrophs, using _________________ _______________________, like Rhodobacter sphaeroides.
Anoxygenic photosynthesis
Aerobic respiration
What is a diazotroph?
Diazotrophs are bacteria and archaea that fix atmospheric nitrogen gas into a more usable form such as ammonia. A diazotroph is a microorganism that is able to grow without external sources of fixed nitrogen
The biochemical pathways of interconversion of small organic compounds are collectively termed ______________ ____________________ and are present in all cells.
Central metabolism
What is a precursor metabolite?
A small organic compound used as a monomer for macromolecule synthesis or a building block for lipid synthesis
True or false?
The pathways of central metabolism, biosynthesis, and macromolecule assembly are nearly identical in all organisms.
True
What three pathways are considered to be a part of central metabolism?
- Glycolytic pathway
- Pentose phosphate pathway
- Citric acid cycle pathway
Which pathway is not considered a part of central metabolism?
The oxoglutarate dehydrogenase pathway
Many organisms lack the alpha-ketoglutarate dehydrogenase enzyme of the TCA. In them the enzymes of the TCA are organized into two separate branches, leading to __________________ and _____________ respectively.
Oxoglutarate/alpha-ketoglutarate dehydrogenase
Succinyl-CoA
Glycolysis provides _______________ and metabolic _________________ for anabolic and catabolic processes.
Energy
Metabolic intermediates
The ________________ ________________ ________________ provides reducing power, nucleic acid precursors, and metabolic intermediates for glycolysis.
Pentose phosphate pathway
The pentose phosphate pathway provides reducing power via what molecule?
Nicotinamide adenine dinucleotide phosphate (NADPH)
What molecule does the pentose phosphate pathway produce that is used for the synthesis of nucleic acids?
Ribose-5-phosphate
What is the importance of erthyrose-4-phosphate in the pentose phosphate pathway?
Erthyrose-4-phosphate is a produce that can be used to build aromatic amino acids
The ________________ ______________ ________________ yields electron carriers and anabolic precursors.
Tricarboxylic acid (TCA) pathway
What enzyme is not considered a part of central metabolism?
Oxoglutarate dehydrogenase
What is the importance of NADPH?
Reducing power
______________________ provides energy and intermediates for anabolism.
Glycolysis
The _______________ _________________ ____________ provides reducing power, ribose-5-phosphate (nucleic acid), erthryose-4-phosphate (aromatic amino acids) and sugar interconversion.
Pentose phosphate pathway
Parts of the __________________ _____________________ _____________________ provide electron carriers for the production of ATP in respiration and precursors for anabolism.
Tricarboxylic acid cycle
The __________________-______________pathway describes an alternate series of reactions that catabolize glucose to pyruvate using a set of enzymes different from those used in either glycolysis or the pentose phosphate pathway.
Entner-Doudoroff
Glycolysis as generally taught is also known as the ________________-________________ or Parnas pathway.
Embden-Meyerhof
There are three distinct features of the Entner-Doudoroff pathway. What are they?
- Occurs only in prokaryotes
- Uses 6-phosphogluconate dehydratase and 2-keto-3-deoxyphosphogluconate aldolase to create pyruvate from glucose
- Yields (net) 1 NADPH, 1 NADH, and 1 ATP
What glycolytic enzyme do prokaryotes that use the Entner-Duodoroff pathway often lack?
Phosphofructokinase-1
What species discussed in class uses the Entner-Douodorff pathway?
Pseudomonas putida
_______________________ __________________ lacks 6-phosphofructokinase and therefore cannot enter the Embden-Meyerhof pathway. In fact, even when transfected with the phosphofructokinase gene, this species will still use the Entner-Doudorff pathway.
Pseudomonas putida
The pathways of central metabolism, biosynthesis and macromolecular assembly are nearly identical in all organisms. This commonaltiy, often termed the _________________ __ __________________, has been used as evidence for the descent of all life on earth from a single common ancestor.
Unity of biochemistry
What enzyme of the TCA is principally found in aerobic chemoheterotrophs?
Oxoglutarate dehydrogenase/alpha-ketoglutarate dehydrogenase
Is the TCA ubiquitous in nature?
No, it is not
In organsims that lack oxoglutarate dehydrogenase/alpha-ketoglutarate dehydrogenase, how is the TCA used?
TCA enzymes are strictly used for biosynthetic purposes, and they have two branches of TCA enzymes
What is the role of TCA in aerobes?
It provides reducing power and electron carriers and can be used for the biosynthesis of amino acids
Can anaerobes without the TCA still respire?
Yes, oxygen is not necessarily needed for respiration
___________________________ normally use the same organic compound for both biosynthesis and respiration.
Chemoheterotrophs
In chemoheterotrophs, the organic carbon souce can be used to general energy via ____________________ _____________________ or chemiosmosis and to build precursor metabolites.
Substrate level phosphorylation
In respiration, how much of the carbon is used for energy and biosynthesis?
1/2 of the carbon is used for energy and byproducts; the other half is used for biosynthesis
Why is fermentation less effective at producing ATP per mole of substrate?
Because fermentation typicalyl generates much less ATP per mole of substrate, fermentative microbes typically ferment about 90% if an organic compound, assimilating only 10% of it
What is the first step in the degradation of most organic matter for prokaryotes?
Hydrolysis to monomers
How do eukaryotic microbes typically hydrolyze organic matter into monomers?
Hydrolysis occurs within phagolysosomes during intracellular digestion; the monomers are then taken into the cytosol by permeases in the phagolysosome membrane
How do prokaryotic microbes typically hydrolyze organic matter into monomers?
Via secretion of extracellular hydrolyases; the monomers are then taken up by active transport
Do members of the fungi kingdom use phagolysosomes to hydrolyze organic matter?
No, they do not
Most solute transport by prokaryotes is by ____________ transport.
Active transport
What must prokaryotes use as active transport?
Environments are low in nutrients
Why are prokaryotic environments often nutrient deficient?
Because of the use of high-affinity permeases; in almost all habitats, almost all of the available soluble nutrients have been assimilated into microbial cells or oxidized to CO2
How is active transport accomplished by prokaryotes?
High-affinity permeases that concentrate the compounds taken up
What types of transport are available to cells? What is/are the differences between them?
In many bacteria, how is sugar uptake accomplished?
The phosphotransferase system
What type of transport is the phosphotransferase system?
Active transport as it allows movement against a concentration gradient
What are the four general steps to the phosphotransferase system?
- Enzyme I phosphorylates itself, using PEP as the high-energy phosphate donor
- Enzyme I transfers the phosphate to a small protein called Hpr
- Hpr transfers the phosphate to one of many different specific sugar permeases in the membrane, called Enzyme II
- The permease transfers the phosphate to the sugar during transfer into the cell
The phosphotransferase system operates via what type of mechanism?
Group translocation
Cells interconvert between two forms of energy. What are they?
An ionic potential and ATP
All cells need chemical energy in the form of ATP, GTP, PEP, and some others. ATP is used in most energy-requiring reactions of biosynthesis. ____ and ___ are frequently used in macromolecular assembly reactions while PEP is used in many transport reactions.
GTP
GTP
Why is phosphorylation important in the phosphtransferase system?
It maintains the concentration gradient required and charges sugar molecules so that they can enter central metabolism
