Lecture 21 Flashcards
_______ and _________ allows microbes to colonize every aspect of every niche in our world.
metabolic potential and versatility
The three energy classes of microbes?
Use Chemotrophy: chemoorganotrophs, chemolithotrophs
Use Phototrophy: phototrophs
If microbes conserve energy from chemicals we call them what?
chemotrophs
If microbes are able to convert light energy into chemical energy, they are called?
phototrophs
Use organic chemicals for energy metabolism
Chemoorganotrophs (heterotrophs)
-most microbes brought into the lab
Chemoorganotrophs can use _____, _____, etc., but in almost all cases, energy is conserved from the _______ of the ________ . The conserved energy is what?
- glucose, acetate
- oxidation of the compound
- trapped in the cell as ATP
Microbes that tap into the oxidation of inorganic chemicals
H2, H2S, Fe, etc.
chemolithotrophs
How do chemolithotrophs and chemoorganotrophs often live?
Near each other. Chemoorganotrophs oxidize organic compounds that produce waste products, such as H2 and H2S, which are then used by chemolithotrophs as an energy source. Living close means less competition for energy.
Microbes that have special pigments that allow them to convert light energy into chemical energy. A significant metabolic advantage because they are not competing for energy from the chemotrophs
phototrophs
Two major forms of phototrophy
oxygenic photosynthesis, and anoxygenic photosynthesis
oxygen is produced via photosynthesis, what prokaryote is an example, and what eukaryote?
oxygenic photosynthesis, and cyanobacteria prok, and algae euk
does not yield oxygen during photosynthesis, and found in what types of bacteria?
anoxygenic photosynthesis
purple and green bacteria, and heliobacteria
Refers to the sum of all chemical reactions within an organism (catabolic and anabolic rxns)
metabolism
Catabolic rxns
Generates what?
when a microorganism consumes large complex molecules for energy, such as carbohydrates (sugars, starches), proteins, or nucleic acids even, they need to break it down to release energy.
Generates smaller molecules (carbs to glucose units, proteins to individual amino acids)
catabolic reactions are generally what?
oxidative. Meaning that there is a removal of electrons from an atom or molecule, a rxn that often produces energy.
The oxidation of large molecules results in what? Some what is released during these reactions?
energy conserved and stored as ATP
-some heat b/c rxn is not 100% efficient
After the breakdown of molecules (catabolic rxn), the cell is now able to go through _____ ?
anabolic reactions
Anabolic reactions
-These rxns require what?
Simple building blocks of Carbon, Hydrogen, and oxygen from the breakdown of carbs, amino acids, nucleotides, lipids, etc. are used to generate larger molecules for the cell, such as using nucleotides to build new cellular DNA and RNA in preparation for cell division, using glycerol and fatty acids to make the phospholipids for a new cell membrane
-input of energy such as ATP to do this work for the cell
Anabolic reactions are primarily _______ (think type of rxn)
reduction, meaning a molecule has gained one or more electrons
Oxidation and reduction rxns are always ______.
Coupled. As one molecule is oxidized, another is simultaneously reduced
ATP is produced when you _______ large complex molecules, and this ATP is then used to ________ new complex molecules.
breakdown, build
Most biological oxidation reactions involve the loss of what? So they are also called what type of reactions?
H atoms (one proton and one electron)
-dehydrogenation reactions
NAD+ accepts ______ and _____.
2 electrons, and 1 proton.
One H+ is left over and is released into the surrounding medium
NAD+ reduced becomes what?
And it contains ______ energy than NAD+.
NADH - can be used to generate ATP
-MORE
Much of the energy released during oxidation-reduction rxns is trapped within the cell by the formation of _______ .
ATP
Specifically, an ________ is added to _______ with the input of energy to from ________ .
inorganic phosphate group is added to ADP to form ATP
The addition of phosphate to a chemical is called
Phosphorylation
Microbes use _____ mechanisms of phosphorylation to generate ATP from ADP. What are they?
three mechanisms:
- substrate-level phosphorylation
- oxidative phosphorylation
- photophosphorylation
~
high energy bond that when broken releases usable energy
ATP is made when a high energy phosphate is directly transferred from a phosphorylated compound (a substrate) to ADP.
How has the phosphate acquired energy here?
substrate-level phosphorylation
-generally, the phosphate has acquired energy during an earlier rxn in which the substrate itself was oxidized
NOTE: the phosphate group does not have to come directly from the substrate
PEP
a substrate that can offer a phosphate group to form ATP. It is a three carbon compound called phosphoenolpyruvate, one of the breakdown products of glycolysis
Oxidative phosphorylation
where does it occur in prokaryotes?
Electrons are transferred from organic compounds to one group of e- carriers (usually to NAD+ and FAD). Then the electrons are passed through a series of different e- carriers to molecules of oxygen or other oxidized inorganic and organic molecules. This sequence of e- carriers used in oxid phosph is called an e- transport chain/system (ETC).
This occurs in the plasma membrane of prokaryotes.
The transfer of e-s from one e-carrier to the next releases energy, some of which is used to make ATP from ADP through a process called _______
chemiosmosis
Photophosphorylation
converts _____ energy to _____ energy of _____ and ______.
occurs only in photosynthetic cells with light trapping pigments like chlorophylls. Organic molecules, especially glucose, are synthesized with the energy of light, CO2 and H2O.
light energy to chemical energy of ATP and NADPH, which in turn are used to make organic molecules.
Light causes chlorophyll to ________ . The energy released from the _________ of chlorophyll through a system of carrier molecules is used to generate ATP.
- to give up electrons
- transfer of electrons (oxidation) of chlorophyll through a system of carrier molecules is used to generate ATP
Metabolism Big Picture
Go back to this
carbohydrates broken down through what pathway? lipids broken down through what pathway?
What eventually enters glycolytic pathway? Process of ________ ?
glycolytic pathways break down carbohydrates, others must be oxidized in separate pathways( beta oxidation pathways break down lipids),
but all of these large biopolymers (protein, nucleic acids, polysaccharides, etc) enter the glycolytic pathway at some point during the process of catabolism.
glucose 6-phosphate made during the first step of glycolysis is metabolized by both the ________ and the _______ pathways.
What does the latter pathway create?
glycolytic pathway, and the pentose phosphate pathway.
-pentose phosphate pathway creates precursors for the synthesis of nucleotides ATGC
Citrate made in the Krebs cycle can go into precursors for _______ _______ synthesis, important for ___________
fatty acid synthesis, important for phospholipids in cell membranes
oxidation and reduction rxns involve
transfer that involves 2 coupled reactions, oxidation and reduction
