Chapter 8 Flashcards
Describe the mitochondrial anatomy being certain to include the five regions/structures we discussed.
The mitochondrion is a double-membraned, rod-shaped structure found in both plant and animal cell. Often referred as the powerhouses of the cell because most of the ATP from cellular respiration is produced in the mitochondria
Outer membrane
Inner membrane
intermembrane
Cristae
Matrix
Outer membrane
The outer membrane and the inner membrane are made of proteins and phospholipid layers separated by the intermembrane space.
The outer membrane covers the surface of the mitochondrion and has a large number of special proteins known as porins.
Inner Membrane
The inner mitochondrial membrane is strictly permeable only to oxygen and ATP molecules. A number of chemical reactions take place within the inner membrane of mitochondria.
intermembrane
Space between the outer and inner membranes
Cristae
Folds of the inner membrane that form a layered structure called cristae, and this helps in increasing the surface area inside the organelle.
Location of the electron transport chain (ETC).
Matrix
a viscous fluid that contains a mixture of enzymes and proteins. It also comprises ribosomes, inorganic ions, mitochondrial DNA, nucleotide cofactors, and organic molecules.
The enzymes present in the matrix play an important role in the synthesis of ATP molecules.
Location of the prep reaction and the citric acid cycle
Name the four phases of cellular respiration.
Glycolysis
Preparatory reaction
Citric acid cycle -
Electronic Transport chain (ETC)
Where does each phase occur?
Glycolysis - occurs in the cytoplasm
Preparatory reaction - takes place in th e matrix of the mitochondrion
Citric acid cycle - takes place in the matrix of the mitochondrion.
Electronic Transport chain (ETC) -occurs in the inner mitochondrial membrane
What are the starting and end products of each phase?
Be sure to include (if applicable) ATP, glucose derived products that go on to another step, and electron carriers).
Glycolysis - the breakdown of glucoses to two molecules of pyruvate (two 3-carbon molecules) Oxidation results in NADH and provides enough energy for the net gain of two ATP molecules
Preparatory reaction - Pyruvate is broken down from a 3-carbon to a 2-carbon acetyl group and 1-carbon (CO) molecule is released.
Citric acid cycle - Each 2-carbon acetyl group matches up with a 4-carbon molecule, forming two 6-carbon citrate molecules. As the bonds are broken and oxidation occurs, NADH and FADH are formed and two CO2 are released and is able to produce one ATP per turn. The cycle turns twice.
Electronic Transport chain (ETC) - receives the electrons that were removed from the glucose breakdown products. NADH and FADH2 gives up thier high-energy electrons to the chain. This energy is used for the production of between 32 and 34 ATP by chemiosmosis . After oxygen receives electrons at the end of the it combines with Hydrogen and becomes water (H2O)
What is anaerobic respiration (also known as fermentation) versus aerobic respiration?
Fermentation uses glycolysis only. Anaerobic respiration uses all three parts of cellular respiration, including the parts in the mitochondria like the citric acid cycle and electron transport; it also uses a different final electron acceptor instead of oxygen gas.
Why does fermentation occur, in other words what is it accomplishing? – It’s getting rid of electrons (know how).
Fermentation is used by organisms to generate ATP energy for metabolism. One advantage is that it requires no oxygen or other external electron acceptors, and thus it can be carried when those electron acceptors are absent. A disadvantage is that it produces relatively little ATP, yielding only between 2 to 4.5 per glucose compared to 32 for aerobic respiration.
The main purpose of fermentation is to regenerate NAD+ by oxidizing NADH. The NAD+ regenerated from fermentation will go back into glycolysis so that this pathway can continue. If the supply of NAD+ stops within the cell, then glycolysis will also stop effectively stopping ATP production.
When an organic compound is fermented, it is broken down to a simpler molecule and releases electrons. The electrons are transferred to a redox cofactor, which in turn transfers them to an organic compound. ATP is generated in the process, and it can be formed by substrate-level phosphorylation or by ATP synthase.
When glucose is fermented, it enters glycolysis or the pentose phosphate pathway and is converted to pyruvate. From pyruvate, pathways branch out to form a number of end products (e.g. lactate). At several points, electrons are released and accepted by redox cofactors (NAD and ferredoxin). At later points, these cofactors donate electrons to their final acceptor and become oxidized. ATP is also formed at several points in the pathway.
What percentage of the energy in glucose is released by anaerobic versus aerobic respiration?
between 31 and 39 (*40) % of the energy released during aerobic respiration
Anaerobic respiration leads to an incomplete breakdown of glucose. It releases around 5% of the energy released by aerobic respiration per molecule of glucose.
Why is pyruvate considered a pivotal metabolite?
Pyruvate is an important intermediary in a number of metabolic activities. It connects processes like glycolysis, gluconeogenesis, fatty acid metabolism, and amino acid metabolism, among others.
The end product of glycolysis, pyruvate exists a a pool of particular substrates that is continuously affected by changes in cellular and environmental conditions. Degradative reactions (catabolism) that break down molecules must be dynamically balanced with constructive reactions (anabolism). When energy needs to be stored as fat, pyruvate is taken from the pool. This dynamic of catabolism and anabolism is essential to optimal cellular function
Glycolysis
o How many ATP are produced directly in glycolysis (both gross and net)?
The energy to split glucose is provided by two molecules of ATP. As glycolysis proceeds, energy is released, and the energy is used to make four molecules of ATP. As a result, there is a net gain of two ATP molecules during glycolysis
Glycolysis
o How many NADH are produced?
During glycolysis, one glucose molecule is split into two pyruvate molecules, using 2 ATP while producing 4 ATP and 2 NADH molecules
