Professor Kristen Przyborski
April 14, 2013
1) In the 1940s, some physicians prescribed low doses of a drug called dinitrophenol (DNP) to help patients lose weight. This unsafe method was abandoned after a few patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+. Explain how this can cause weight loss. In a coupled reaction, an exergonic reaction provides the energy needed to drive an endergonic reaction. People use the energy released by exergonic reactions such as the breakdown of glucose into carbon dioxide and water to drive endergonic reactions such as the synthesis of proteins from amino acids. In coupled reactions, energy is transferred from place to place by energy carrier molecules such as ATP. In this role as an intermediary in coupled reactions, ATP is constantly being synthesized to capture energy released during exergonic reactions and then broken down to power endergonic reactions (102).The electron transport chain converts energy and uses the exergonic flow of electrons to pump hydrogen ions across the mitochondrial membrane. In the DNP case hydrogen ions “leaked” back across the membrane, diffusing down its gradient. When the mitochondrial membrane became "leaky" to hydrogen ions chemiosmosis stopped because there wasn't a gradient of protons between the outside and inside of the membrane. Without a gradient of protons the majority of the ATP produced by cellular respiration couldn't be produced which is essential to make fatty acids and breakdown glucose, therefore the energy in a persons metabolism comes from stored fat or protein, causing a person to lose weight as well as causing a lack of energy. In the same sense the body must find another source of energy to give the body enough ATP to survive, unfortunately in the DNP case it lead to death.
Audesirk, Teresa. Audesirk, Gerald. Byers, Bruce. Biology Life on Earth with...
Cited: Audesirk, Teresa. Audesirk, Gerald. Byers, Bruce. Biology Life on Earth with Physiology. Ninth Edition 2011. April 12, 2013
Please join StudyMode to read the full document