cellular respiration essays

cellular respiration essays Cellular respiration begins with glucose. Glucose is the primary fuel used in glycolysis, the first stage of cellular respiration. This molecule is found in the gel-like substance called cytoplasm that fills the cell. In glycolysis, glucose undergoes phosphorylation by ATP. The ATP is converted back to ADP. The glucose molecule is rearranged and undergoes a second phosphorylation by ATP. The second ATP is also converted back to ADP. Glucose, a six-carbon molecule, is split into 2 three-carbon molecules of PGAL. As oxidation takes place, NAD picks up a hydrogen atom from each molecule to form 2NADH. Phosphorylation takes place again. For each molecule, 2ADP combine with two phosphates to form a total of 4 ATP, and pyruvic acid molecules are formed. A net gain of 2 ATP have been formed. As the pyruvic acid molecules make their way toward the mitochondria, two more molecules of NADH are formed. A carbon atom also breaks off and combines with two oxygen atoms to produce the waste product carbon dioxide. As a result of these reactions, each pyruvic acid molecule is transformed into a two-carbon compound called an acetyl group. The two acetyl groups combine with a molecule of coenzyme A each to form two acetyl coenzyme A molecules. These molecules are processed in a complex pathway called the Krebs cycle. As the Krebs cycle progresses through both pyruvic acid molecules, six molecules of NADH, two molecules of ATP, and additional carbon dioxide are all formed. FAD picks up a hydrogen atom from each pyruvic acid molecule, and a total of 2 FAD2 are formed. NADH and FAD2 transport their hydrogen atoms and electrons to the electron transport chain. The electrons are passed down the chain of attracting molecules until they reach oxygen. Joined with hydrogen, they combine with the oxygen to form water. As the electrons flow down the electron chain, they release energy that is used to make more ATP. Eight of the ten NADH f ...

Magic Colored Milk Science Project

Magic Colored Milk Science Project If you add food coloring to milk, not a whole lot happens, but it only takes one simple ingredient to turn the milk into a swirling color wheel. Here is what you do. Magic Milk Materials 2% or whole milkfood coloringdishwashing liquidcotton swabplate Magic Milk Instructions Pour enough milk onto a plate to cover the bottom.Drop food coloring into the milk. Dip a cotton swab in dishwashing detergent liquid.Touch the coated swab to the milk in the center of the plate.Dont stir the milk; it isnt necessary. The colors will swirl on their own as soon as the detergent contacts the liquid. How the Color Wheel Works Milk consists of a lot of different types of molecules, including fat, protein, sugars, vitamins, and minerals. If you had just touched a clean cotton swab to the milk (try it!), not much would have happened. The cotton is absorbent, so you would have created a current in the milk, but you wouldnt have seen anything especially dramatic happen. When you introduce detergent to the milk, several things happen at once. The detergent lowers the surface tension of the liquid so that the food coloring is free to flow throughout the milk. The detergent reacts with the protein in the milk, altering the shape of those molecules and setting them in motion. The reaction between the detergent and the fat forms micelles, which is how detergent helps to lift grease off of dirty dishes. As the micelles form, the pigments in the food coloring get pushed around. Eventually, equilibrium is reached, but the swirling of the colors continues for quite a while before stopping.