Microbial Metabolism Flashcards
Look-up the structures of pyruvic acid and lactic acid. Which is more oxidized? Which is more reduced? Which would provide more energy to a cell that uses it for food?
Pyruvic acid is oxidized and lactic acid is reduced. Reduced provides more energy.
Look-up the structures of acetaldehyde and ethanol. Which is more oxidized? Which is more reduced? Which would provide more energy to a cell that uses it for food?
Acetaldehyde is more oxidized. Ethanol is more reduced. Ethanol would provide more energy to a cell that uses it for food because it’s more reduced and has the higher free energy.
Look-up the structures of glyceraldehyde and glycerate. Which is more oxidized? Which is more reduced? Which would provide more energy to a cell that uses it for food?
glycerinate is reduced and glyceraldehyde is oxidized. The reduced has higher free energy.
Imagine a microbe uses both glycerate and acetaldheyde as food molecules. These molecules become oxidized completely. What is the chemical formula for the carbon-containing molecules that are produced from their complete oxidation?
Glycerate completely oxidized becomes pyruvate in glycolysis. Acetaldehyde can be further oxidized by acetaldehyde dehydrogenase into acetic acid.
Why are lipids twice as energy dense as other biological macromolecules?
The fatty acid tails are rich in carbon carbon and carbon hydrogen bonds. These are lipids. They have mostly just carbon and hydrogen atoms. And so the tail portion of a phospholipid is very energy rich. Fats and lipids generally have a lot of energy because they have these fully reduced carbon atoms that have nearly the maximum number of connections to hydrogen.
Sugars, nucleotides, and amino acids are all about the same in terms of their energy density, but lipids are about twice as dense when it comes to energy.
Define: metabolism, catabolism, anabolism.
Catabolism refers to those chemical reactions that a cell performs that takes a complex molecule and makes it into a simple molecule.
Anabolism means taking a simple molecule and making a complex molecule.
metabolism is all of the chemical reactions in a cell. 90% of those reactions are dependent on enzymes.
Describe 2 catabolic reaction types. Which one releases usable energy?
If you were to convert polysaccharide into a set of single sugars, a bunch of monosaccharides, that would be catabolism. That form of catabolism is hydrolysis. Hydrolysis does not release much energy. It’s considered energy neutral. But it does create smaller molecules that can undergo further breakdown. We take a glucose and we convert it to carbon dioxide and water, well carbon dioxide molecules and water molecules are much simpler than glucose molecules. So this is yet another form of catabolism. This would be an oxidation reaction. An oxidation reaction releases energy that a cell can capture. One way cells capture energy is they use the released energy to build ATP.
Describe 1 anabolic reaction. What is the relationship of this reaction to energy?
One example of a common anabolic process that all cells do is they connect amino acids together to make proteins. It goes from simple amino acid molecules to much more complicated poly peptides that then fold and stick together to make proteins. This type of chemical reaction is a dehydration synthesis reaction, and to do it randomly, to have amino acids randomly stick together is almost energy neutral. Meaning it doesn’t require nor does it release energy. But to do it in exactly the right order to make the correct poly peptide to make the right folded protein it’s very energy intensive. So if you have 200 amino acids and 1000 ATP molecules, you can make your average polypeptide or your average simple protein.
Name 3 electron carriers in their oxidized and reduced forms. How do these molecules carry energy from place to place within a cell?
We symbolize a nicotinamide adenine dinucleotide where one of the rings has a positive charge, we would symbolize that as NAD+. NAD+ is the electron hungry form of NAD. If we apply energy in the form of high energy electrons and a hydrogen ion, we can get one of the hydrogen ions to stick to the ring, and we can use the extra electron to get rid of the positive charge. So if we think about this as energy coming in the form of electrons, the first electron neutralizes the positive charge. The second electron allows a hydrogen ion to stick. We now have nicotinamide adenine dinucleotide in its reduced form which we write as NADH. So the oxidized or an electron hungry form is NAD+. And the reduced or electron rich form is NADH. And this is a kind of chemical reaction that is used to take energy away from food molecules.
NAD+ can be reduced by receiving electrons to become NADH. FAD stands for flavin adenine dinucleotide, and it can be reduced by receiving two electrons to become FADH2. NADP+ is nicotinamide adenine dinucleotide with an extra phosphate that becomes reduced to become NADPH.
Name another energy carrier that does not get oxidized or reduced when it carries energy from place to place within a cell.
ATP —> ADP +Pi
What is the energetic relationship between catabolism and anabolism?
Catabolic processes release energy. The energy that’s released is captured and some kind of intermediate molecule. And then anabolic reactions need energy. They use energy and the intermediate molecule provides the energy to do that anabolic process. For example, the oxidation of glucose into carbon dioxide and water releases energy the cell captures. One of the ways the cell captures the energy is ATP. Building proteins from amino acids requires energy and the cell provides that energy as ATP. ATP then breaks down to ADP and phosphate, which through catabolism becomes ATP again. And so there’s a cycle of little energy carriers from catabolic reactions to anabolic reactions.
Nucleotides are connected to make mRNA. Is this anabolism or catabolism?
anabolism
Fatty acids are broken into multiple acetyl CoA molecules. Is this anabolism or catabolism?
catabolism
A 4-carbon organic molecule becomes 4 CO2 molecules. Is this catabolism or anabolism? Is there any other term that applies? Explain.
Anabolism because you’re building the organic molecules to form the 4 carbon dioxide molecules. Oxidation is also another term that applies because organic refers to a molecule that has carbon carbon and carbon hydrogen bonds. And so as we proceed from the fully reduced form of carbon to the fully oxidized form of carbon, energy is released from molecules. If you take methane, which is the main component of natural gas, and you burn it, the carbon atoms in the methane become the carbon atoms in carbon dioxide. And in that process light and heat are produced.
What are the 4 phases of cell respiration? Which phases produce CO2? Which phase uses O2? Which phases directly make ATP? Which phases make electron carriers? Which phase can convert the energy in reduced electron carriers into the energy in ATP?
Glycolysis, pyruvate oxidation, the citric acid cycle and electron transport, are commonly said to be the four phases of aerobic cell respiration. Phase 2 is where we first see CO2 as a product and phase 3. The first phase, glycolysis, produces a small amount of ATP directly. 4th phase can convert energy in reduced electron carriers into ATP.
