Energy and metabolism conduction,convection,radiation by Muhammad Fahad Ansari 12IEEM14
Energy and MetabolismMuhammad Fahad Ansari 12IEEM14
The Energy of Life• The living cell generates thousands of different reactions• Metabolism – Is the totality of an organism’s chemical reactions – Arises from interactions between molecules• An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics
• Metabolic Pathways Biochemical pathways are the organizational units of metabolism• Metabolism is the total of all chemical reactions carried out by an organism• A metabolic pathway has many steps that begin with a specific molecule and end with a product, each catalyzed by a specific enzyme• Reactions that join small molecules together to form larger, more complex molecules are called anabolic.• Reactions that break large molecules down into smaller subunits are called catabolic. Enzyme 1 Enzyme 2 Enzyme 3 A B C D Reaction 1 Reaction 2 Reaction 3 Starting Product molecule
Metabolic Pathway• A sequence of chemical reactions, where the product of one reaction serves as a substrate for the next, is called a metabolic pathway or biochemical pathway• Most metabolic pathways take place in specific regions of the cell.
Bioenergetics• Bioenergetics is the study of how organisms manage their energy resources via metabolic pathways• Catabolic pathways release energy by breaking down complex molecules into simpler compounds• Anabolic pathways consume energy to build complex molecules from simpler ones
Energy• Energy is the capacity to do work or ability to cause change. Any change in the universe requires energy. Energy comes in 2 forms: – Potential energy is stored energy. No change is currently taking place – Kinetic energy is currently causing change. This always involves some type of motion.
Forms of Energy• Kinetic energy is the energy On the platform, a diver has more potential energy. Diving converts potential energy to kinetic energy. associated with motion• Potential energy – Is stored in the location of matter – Includes chemical energy stored in molecular structure• Energy can be converted from one form to another Climbing up converts kinetic In the water, a diver has energy of muscle movement less potential energy. to potential energy.
Laws of Energy Transformation• Thermodynamics is the study of energy changes.• Two fundamental laws govern all energy changes in the universe. These 2 laws are simply called the first and second laws of thermodynamics:
The First Law of Thermodynamics• According to the first law of thermodynamics – Energy cannot be created or destroyed – Energy can be transferred and transformed Chemical energy For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement
Second Law of Thermodynamics• The disorder (entropy) in the universe is continuously increasing. – Energy transformations proceed spontaneously to convert matter from a more ordered, less stable form, to a less ordered, more stable form – Spontaneous changes that do not require outside energy increase the entropy, or disorder, of the universe – For a process to occur without energy input, it must increase the entropy of the universe
Second Law some of the energy dissipates into the– During each conversion, of Thermodynamics environment as heat.– During every energy transfer or transformation, some energy is unusable, often lost as heat– Heat is defined as the measure of the random motion of molecules– Living cells unavoidably convert organized forms of energy to heat– According to the second law of thermodynamics, every energy transfer or transformation increases the entropy (disorder) of the universe Heat co2 + H2O For example, disorder is added to the cheetah’ssurroundings in the form of heat and the small molecules that are the by-products of metabolism.
Biological Order and Disorder• Cells create ordered structures from less ordered materials• Organisms also replace ordered forms of matter and energy with less ordered forms• The evolution of more complex organisms does not violate the second law of thermodynamics• Entropy (disorder) may decrease in an organism, but the universe’s total entropy increases
Biological Order and Disorder• Living systems – Increase the entropy of the universe – Use energy to maintain order – A living system’s free energy is energy that can do work under cellular conditions – Organisms live at the expense of free energy 50µm
Free Energy• Free energy is the portion of a system’s energy that is able to perform work when temperature and pressure is uniform throughout the system, as in a living cell• Free energy also refers to the amount of energy actually available to break and subsequently form other chemical bonds• Gibbs’ free energy (G) – in a cell, the amount of energy contained in a molecule’s chemical bonds (T&P constant) • Change in free energy - ΔG – Endergonic - any reaction that requires an input of energy – Exergonic - any reaction that releases free energy
Exergonic reactions• Reactants have more free energy than the products• Involve a net release of energy and/or an increase in entropy• Occur spontaneously (without a net input of energy) Reactants Amount of energy released Free energy (∆G <0) Energy Products Progress of the reaction (a) Exergonic reaction: energy released
Endergonic Reactions• Reactants have less free energy than the products• Involve a net input of energy and/or a decrease in entropy• Do not occur spontaneously Products Amount of energy Free energy released (∆G>0) Energy Reactants Progress of the reaction (b) Endergonic reaction: energy required
Understanding Heat Transfer,Conduction, Convection and Radiation
Heat Transfer• Heat always moves from a warmer place to a cooler place.• Hot objects in a cooler room will cool to room temperature.• Cold objects in a warmer room will heat up to room temperature.
Question• If a cup of coffee and a red popsickle were left on the table in this room what would happen to them? Why?• The cup of coffee will cool until it reaches room temperature. The popsickle will melt and then the liquid will warm to room temperature.
Heat Transfer Methods• Heat transfers in three ways: –Conduction –Convection –Radiation
Conduction When you heat a metal strip at one end, the heat travels to the other end. As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this? Conduction
Metals are different The outer e______ of metal atoms lectrons drift, and are free to move. When the metal is heated, this ‘sea of electrons’ gain k_____ energy and transfer it inetic throughout the metal. Insulators, such as w___ and p____, do not have this ‘sea of ood lastic electrons’ which is why they do not conduct heat as well as metals.
Why does metal feel colder than wood, if theyare both at the same temperature? Metal is a conductor, wood is an insulator. Metal conducts the heat away from your hands. Wood does not conduct the heat away from your hands as well as the metal, so the wood feels warmer than the metal.
Convection What happens to the particles in a liquid or a gas when you heat them? The particles spread out and become less dense. This effects afluid movement. What is or gas. A liquid fluid?
Fluid movement Cooler, more d____, fluids ense sink through w_____, less armer dense fluids. In effect, warmer liquids and gases r___ up. ise Cooler liquids and gases s___. ink
Water movement Cools at the Convection surface current Cooler Hot waterwater sinks rises
Cold air sinks Where is the Freezer freezer compartment compartment put in a fridge? It is warmer at the bottom, so this warmer air It is put at the top, rises and a because cool air convection sinks, so it cools the current is set up. food on the way down.
The third method of heat transfer How does heat energy get from the Sun to the Earth? There are no particles between the Sun and the Earth so it CANNOT travel by conduction or by convection. RADIATION ?
Radiation Radiation travels in straight lines True/False Radiation can travel through a vacuum True/False Radiation requires particles to travel True/False Radiation travels at the speed of light True/False
Emission experiment Four containers were filled with warm water. Which container would have the warmest water after ten minutes? Dull metal Shiny black Shiny metal Dull black shiny metal The __________ container would be the warmest after ten minutes because its shiny surface reflects heat radiation back _______ dull black into the container so less is lost. The ________ container emitting would be the coolest because it is the best at _______ heat radiation.
Absorption experimentFour containers were placed equidistant from a heater. Whichcontainer would have the warmest water after ten minutes? Dull metal Shiny black Shiny metal Dull black dull black The __________ container would be the warmest after ten radiation minutes because its surface absorbs heat _______ the best. shiny metal The _________ container would be the coolest because it is absorbing the poorest at __________ heat radiation.
Convection questions Why does hot air rise and cold air sink? Cool air is more dense than warm air, so the cool air ‘falls through’ the warm air. Why are boilers placed beneath hot water tanks in people’s homes? Hot water rises. So when the boiler heats the water, and the hot water rises, the water tank is filled with hot water.
Radiation questions Why are houses painted white in hot countries? White reflects heat radiation and keeps the house cooler. Why are shiny foil blankets wrapped around marathon runners at the end of a race? The shiny metal reflects the heat radiation from the runner back in, this stops the runner getting cold.
1. Which of the following is not amethod of heat transfer? A. Radiation B. Insulation C. Conduction D. Convection
2. In which of the following arethe particles closest together? A. Solid B. Liquid C. Gas D. Fluid
3. How does heat energy reachthe Earth from the Sun? A. Radiation B. Conduction C. Convection D. Insulation
4. Which is the best surface forreflecting heat radiation? A. Shiny white B. Dull white C. Shiny black D. Dull black
5. Which is the best surface forabsorbing heat radiation? A. Shiny white B. Dull white C. Shiny black D. Dull black