Micro Chap 5/Exam 2
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What are the different types of nutrient molecules?
Carbs, lipids, proteins
- -these are nutrients for both normal microbiota and animal pathogens
- -practically any organic molecule can be used as a nutrient by some microbes
What are the characteristics of a nutrient molecule?
- 1. Carbon Backbone
- -raw material for building
- 2. Covalent bonds
- -shared electrons
- -energy source; moving e- possess energy
What is the goal of microbial metabolism?
- 1. use nutrients to produce energy and material to make more microorgamism
- -growth is the main goal
- 2. use of nutrients to produce energy to power microbial life
- -energy is the minor goal
What is the difference between the goals of microbial metabolism and animal metabolism?
Microbial metabolism's main goal is growth while animal metabolism's main goal is energy for sustaining life.
What is the role of extracellular enzymes?
- They are made and secreted by microbes to break down (catabolize) nutrients so that they can pass into the cell
- -takes the big molecules and breaks them down into building blocks
Describe the concept of a metabolic pathway
- -a coordinated chain of reactions
- -practically all steps are catalyzed by an enzyme
- subtrate: first nutrient
- end-product: last nutrient
- by product: produced along the way
- intermediate: nutrients that are steps in the process
What is the role of membrane transport proteins?
substrate specific proteins which take the building blocks and import them into the cell
What does it mean that metabolism is chemistry?
A series of catabolic and anabolic reactions
- catabolic reactions: breaking of bonds into smaller molecules
- -releases energy
- anabolic reactions: building of bonds and larger molecules
- -requires energy
What are the metabolic pathways?
glycolysis, pentose phosphate pathway, Kreb's cycle, and fermentation
What are the products of metabolic pathways?
- Reducing Power-NADH, NADPH
- High Energy Phosphate-ATP
- Essential metabolites- 12 of them
What is biosythesis?
- When the bug builds building blocks
- -builds monomers
- *NADPH is key for biosynthesis
What are the four important things to remember about biosynthesis?
- 1. End product is always a building block/monomer
- 2. Substrates are always essential metabolites
- 3. ATP is always needed (energy require for building)
- 4. NADPH is always needed (NADH will be used in electron transport chain)
What kind of pathway are biosynthesis and assembly reactions?
What is polymerization and what does it always require?
-Monomers being built into polymers which can then be assembled into cell structures
-always requires ATP
What had reducing power?
NADH, FADH2, NADPH via redox reactions
What is a redox reaction?
- occurs when one molecule takes the electrons (usually 2) and Hydrogen from another atom
- -the "taker" is reduced (taking the electrons makes it more negative, hence the name reduced)
- -the "loser" molecule is oxidized
- NAD+ + 2e- + H --> redox--> NADH
- FAD+ + 2e- + H -->redox--> FADH2NADP+ + 2e- +H -->redox-->NADPH
- **the results of the above reactions now have reducing power
What is reducing power?
- molecules which have been reduced are said to having reducing power because of what they can now do-reduce others with what they have taken!
- ex: see bio-synthetic pathway
*NADH and FADH2
donate their e-
to the proteins found in an electron transport chain
What does it mean that fermentation is "glycolysis plus"?
Fermentation also uses sugars and begins like glycolysis but it has an extra step the pyruvates are reduced, resulting in different products such as lactate, ethanol, and carbon dioxide
see table 5.4 for examples
What are some ways to produce ATP?
- -fermentation (no O2 required)
- -Anaerobic respiration
- -photosynthesis (produces O2)
- -aerobic respiration (requirea O2)
What is really the main goal behind fermentation?
While fermentation produces ATP, the main foal is to get NAD through a redox reaction because the cell only has a finite number of it
What is the requirement of respiration?
- -NADH/FADH2 molecules
- -electron transport chain
- -ATP synthase enzymes
- -a supply of inorganic e- acceptor molecules
What is the difference between anaerobic and aerobic respiration in the electron transport chain?
- The inorganic electron acceptor
- -if it is anything other than oxygen, it is anaerobic
Describe what is happening here
- NADH or FADH2 enters the electron transport chain. It reduces the transport protein and becomes NAD or FADH. The protein pumps the H+ (protons) out of the cell while passing the electrons on to the next protein.
- Here, O2 is the inorganic final electron acceptor and the bi-product is water.
- ATP synthase turns clockwise under the H+ (proton) gradient entering the cell, which creates ATP from ADP
- *ATP Synthase must turn clockwise due to diffusion into the cell, or ATP wont be produced
- *the proteins pump out H+ along the way to create the proton gradient
What are some unusual nutrients that microbes have been known to utilize?
petroleum, glue, saline-pretty much anything with carbon and covalent bonds
What are the two fates of an essential metabolite?
- To go back into a certain metabolic pathway (such as Acetyl CoA into the Kreb's cycle)
NADH and NADPH are used for different things, what are they?
NADH is used in the electron transport chain
NADPH is used in biosynthesis
What are some of the benefits of microbial fermentation to humans?
- Fermentation creates biproducts that we can use! such as:
- ethanol for beer, wine, and gasoline
- lactate for cheese and sauerkraut
- acetic acid for vinegar
- methane for fuel
see table 5.4 for more
What is the Pasteur effect?
Pastuer found that in the absence of O2, yeast would use the sugars in the medium to produce ATP through fermentation. However, when they were exposed to O2, they switched to aerobic respiration and less sugar is used as food. If there is no sugar available, the yeast will go through aerobic respiration. Yeast is a facultative aerobe and needs less sugar in the presence of O2
what do "photoautroph" and "chemoheterotroph" mean?
photoautotroph: uses CO2 as it's carbon source and light as its energy source
Chemoheterotroph: uses organic molecules as it's carbon source, and electrons from organic molecules
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