Microbiology review sheet cellular respiration
What is cellular respiration?
The process by which living organisms aerobically harvest energy from food.
Name the 3 major events that make up cellular respiration.
1. Glycolysis- The breakdown of glucose by enzymes, releasing energy and pyruvic acid. Produces a small amount of ATP and NADH (2)and it occurs in the cytoplasm.
2. Krebs's cycle-One of the major metabolic pathways of cellular respiration, and involves a cyclic series of enzymatic reactions by which pyruvate converted into Acetyl Coenzyme A is completely oxidized to CO2 and hydrogen is removed from the carbon molecules, transferring the hydrogen atoms and electrons to electron-carrier molecules (e.g. NADH and FADH2) as well as the metabolic energy to high energy bonds (e.g. ATP).
3. Electron Transport Carrier (ETC)- A group of compounds that pass electron from one to another via redox reactions coupled with the transfer of proton across a membrane to create a proton gradient that drives ATP synthesis.
Krebs's cycle purpose
The Krebs cycle is the stage of cellular respiration following glycolysis and decarboxylation of pyruvate. The carbon dioxide produced from the complete oxidation of pyruvate is removed from the cell into the blood. The electron and hydrogen carriers, NADH and FADH2, donate these electrons to the electron transport chain to generate ATP via oxidative phosphorylation, the final metabolic pathway of cellular respiration.
Glycolysis literally means "splitting sugars." Glucose, a six carbon sugar, is split into two molecules of a three carbon sugar. In the process, two molecules of ATP, two molecules of pyruvic acid and two "high energy" electron carrying molecules of NADH are produced. Glycolysis can occur with or without oxygen. In the presence of oxygen, glycolysis is the first stage of cellular respiration. Without oxygen, glycolysis allows cells to make small amounts of ATP. This process is called fermentation.
Electron Transport Chain purpose
The major role of electron transport chain is to extract energy via redox reactions in cellular respiration and photosynthesis.
In eukaryotes, the electron transport chain can be found in the inner mitochondrial membrane where it serves as the site of oxidative phosphorylation. It is also found in the thylakoid membrane of the chloroplast in photosynthetic organisms.
In bacteria, the electron transport chain is located in their cell membrane
What is the overall purpose of cellular respiration?
Aerobic cellular respiration is the harvesting of energy (for ATP synthesis) from
the degradation of food molecules (carbohydrates, lipids, and proteins).
Which of the 3 events make the most ATP?
Is energy removed or added during oxidation?
energy is being lost LEO says GER/OIL RIG)
Is energy being removed or added during reduction?
energy is being added
How does chemiosmosis work? What is its purpose?
Chemiosmosis is the generation of ATP using the ETC and ATP synthase. The carrier molecule actively carries the H+ molecule across the membrane. The H+ concentration builds increasing potential energy- proton motive force. The H+ diffuses across the protein channels using ATP synthase. Has to use ATP synthase because of the charge. Diffuses (going from a high--->low concentration)and enters back into the cell.
The purpose is to make ATP- most of a cell's ATP is made here.
Why do electrons go one way in the ETC?
The chain proteins pass the electrons one to another. Each succeeding protein is
more electronegative than the previous and so is more attractive to electrons and thus passed in a one way direction.
Why does the cell make more ATP from NADH than from FADH2?
NADH donates H and e- "higher up" in the ETC than FADH2. i.e. FADH2 bypasses complex I.
FADH2 releases its electrons at a lower level along the chain than does NADH. The electrons of the former coenzyme thus pass along fewer electron acceptors than NADH, and this difference is reflected in the number of ATP molecules produced.
What is the difference between cellular respiration (aerobic or anaerobic) and fermentation?
No Krebs's cycle or ETC
Starts with organic molecule and ends with final electron acceptor being organic.
Doesn't use oxygen
Produces either Alcohol or acid
yields very small amount of ATP
NAD+ is regenerated in second stage
What is the purpose of fermentation?
Metabolic process used to extract energy from a sugar or other organic molecule.
If an organism can conduct cellular respiration aerobically or anaerobically which does it prefer?
aerobic it produces more ATP