Chapter 4 The Energy of Life PDF

The energy of life Chapter 4 1  Energy According to physicists energy is the ability to do work. Energy gives life the ability to re-arrange molecules, fix broken parts, reproduce, traffic substan...

The energy of life Chapter 4 1  Energy According to physicists energy is the ability to do work. Energy gives life the ability to re-arrange molecules, fix broken parts, reproduce, traffic substances in and Even when you are out of the cell, etc. asleep your cells are still working and using energy. There is energy in the earth evident from volcanoes and geysers. 2  Energy can be in one of two states at any given time. One state is potential energy. When energy is stored then it is in the …food is an form of potential energy. example of Stored energy will be potential energy. released later and cause motion in systems. Another common Cells store energy in chemical bonds such as… form of chemical..ATP, which is a energy is glucose. molecule that stores energy temporarily, but releases it easily for cell functions. 3  Kinetic energy is the other state of energy. The second state energy can be …ATP when it loses a phosphate. found in is kinetic energy. When energy is in kinetic form it is causing motion of atoms/molecules. Some examples of kinetic energy include… …muscle contraction while the body is moving. …light. 4  First Law of Thermodynamics The first law of thermodynamics states that energy can neither be created nor destroyed. Light energy This means the amount of energy in the universe is constant. Living organisms are dependent upon changing energy into different types. For example: Photosynthesizing organisms take light energy and The tree has convert it into chemical energy. chemical energy H2O + CO2 + light energy  that is the result of converting O2 + Sugar light energy into The sugar is the result of chemical energy. We are all converting light energy into solar chemical energy. powered. 5  Second Law of Thermodynamics The second law of thermodynamics states that when energy is converted from one form to another then it is not 100% efficient. When running, Through the process of converting your you use stored stored chemical energy into kinetic chemical energy energy, you lose some of that stored to convert it energy to the form of heat energy. Your into kinetic body as a result becomes warmer and energy which you radiate the heat out of your body. results in muscle motion. All energy through time moves to state of entropy or disorder. Closed systems become more and more disordered with time. 6  Does life somehow defy the 2nd law of thermodynamics? Living organisms not only maintain order, but increase in order over time. As individuals we grow and develop. In populations organisms change and become more complex through evolution. Organisms are not closed systems. They receive energy from the sun (and some organisms the earth). The sun radiates heat and light and this energy is intercepted by the earth. Living organisms are recipients of this energy. Remove the sun and you will remove the 7 ability for living  Metabolism Chemical reactions are the results of Metabolism is the molecules and energy interacting with summation of all one another. the chemical They result in new molecules reactions which forming and energy changing occur in a living forms. body. Digesting your cereal is an example of metabolism. Then using that energy you gained Everything you do involves metabolism!!!! from the cereal to study is still a form8  Some chemical reactions absorb energy Some reactions require an input of energy for the reaction to occur. This reaction results in kinetic energy being converted to potential energy. Endergonic Reactions are reactions which store energy from an input of energy from another system. Photosynthesizers take the sun’s light anddioxide Carbon stores + it water in the +light form of The act of building chemical energy. energy leads to glucose and a sand castle molecular oxygen (O2). Glucose is requires an input the result of storing solar energy. of energy and Because there is an outside energy results in a input, the products have more structure storing energy than the reactants. that energy. dergonic reactions in living organisms build macromolecules. 9  Some chemical reactions release energy Other chemical reactions release energy. In these reactions the products have less energy than the reactants. These reactions are called exergonic reactions. Cellular respiration is the chemical break down of sugars Energy previously stored in resulting in energy glucose through release. photosynthesis is released (exergonic) through cellular respiration. The sun’s heat and light is an example of exergonic reactions. 10  Reactions rates are in balance Chemical reactions can often go from one direction (H2 + O2  H2O) to the other direction (H2O  H2 + O2) Cells want to avoid this process so the products of one reaction will become the reactants of another chemical reaction. This process is called a metabolic pathway. A distinct set of events (chemical reactions) which ultimately result in the removal of waste materials or the storage of energy. DNA replication is an example of a metabolic pathway. This results in the formation of new DNA structures so reproduction 11 can take place.  Flow of electrons from one molecule to another moves energy Electrons can carry energy and An electron transport chain can be moved from one are the results of atom/molecule to another specialized proteins which atom/molecule. This is called an oxidation- pass electrons from protein to protein. Oxidation reduction reaction means or of the loss Used in the process of “redox”. electrons from a molecule or moving energy a lot atom. like electricity. This is an exergonic Fig. 4.6 p. 75 Reduction means the gain of reaction. an electron. Destructive This is an endergonic reaction. Constructive Oxidation and reduction reactions occur simultaneously. If one molecule is oxidized (loses electrons) then 12 another is reduced (gains  ATP is the energy currency of a cell Adenosine Triphosphate (ATP) is a molecule used to temporarily store energy and release energy for cellular functions. It consists of an adenine (one of the 5 nucleotides) and three phosphate molecules Fig. 4.7 p.76 In eukaryotic cells mitochondria produce ATP. ATP is used in all three domains of life as the energy currency. The lions, the grass, the trees, and all the other forms of life use ATP. Including you!!!! 13  Coupled Reactions Exergonic Potential energy ATP ADP + Pi Kinetic energy Endergonic Is the result of recycling ATP molecules. When an ATP molecule is used it forms an Adenosine Diphosphate molecule (ADP) plus an inorganic phosphate (Pi) which can be later reattached by the input of some sort of energy and a metabolic pathway. 14  Energy is transferred when a Phosphate is released from an ATP molecule. Phosphorylating is the transferring During photosynthesis the use of of a phosphate from one molecule ATP produced through the light (ATP) to another molecule. dependent reaction increase the The transfer may induce one likelihood of the bonding of hydrogen, carbon, and oxygen to of two new molecular form glucose. conditions. 1.) May result in a new shape of the target molecule. May open an active transport protein to allow the motion of matter through the In the picture she is membrane. thinking about 2.) Through energizing photosynthesis.  another molecule it may increase the likelihood of 15 the molecule bonding  ATP represents short term energy storage A typical human goes through 2 billion ATP molecules a minute. The third phosphate is Are you very unstable and won’t serious?! stay bonded with the ?!? molecule for too long. Long term energy storage is done in the form of starch (plants), glycogen (animals), fats, etc. 16  Enzymes speed up chemical reactions Enzymes are organic (protein) A lot of the molecules which increase the organelles found rate at which chemical in eukaryotic reactions occur (catalyze) organisms are Among the most important membrane sacs biological molecules. filled with particular Enzymes do some of these functions… enzymes. 1.) build DNA Lysosomes 2.) digest food Peroxisomes 3.) store energy Mitochondria 4.) transfer information Etc. Hooray for enzymes! !! 17  Enzymes lower the activation energy Activation energy is the amount of energy This is the same as necessary for a chemical reaction to occur. when you first go to An input of energy is necessary for a pick something up. It reaction to take place. requires an input of Enzymes lower the activation energy by energy to start the these 4 processes. process 1.) Put substrates (reactants) together 2.) Orient substrates in the proper position. 3.) Move water out of the way 4.) Changing the shape of molecules so The they will active fit.is(induce site a fit) a portion of the protein where the molecule(s) fit in the enzymes. This is where the enzyme does its work. Enzymes active site accepts the substrate and creates an enzyme- substrate complex. Then the reaction is completed and the 18  Cofactors Cofactors are substances that must be present for an enzyme to catalyze a chemical reaction. Cofactors return to their previous state (structure and/or charge) when Copper,Iron,and theall zinc are reaction is complete. Common metal cofactors. Fe Organic molecule cofactors are called coenzymes. A lot of vitamins are coenzymes. 19  Negative feedback loop A negative feedback loop is when the products of a reaction inhibit the continuation of the reaction. When you body overheats you sweat and through evaporation you cool your body off. Once you are at normal temperature you stop sweating. In enzymes the product of the reaction inhibits the enzymes from continuing to function. When the product is too high, the product of the reaction fits In the diagram into thebelow enzymethechanging the product of shape the third of the enzyme. enzyme can inhibit the first protein and subsequently inhibit the metabolic pathway. Enzy produc Enzym Produ Enzy me t e ct me product 20  Inhibitors nhibitors are agents which stop enzymes from functioning. Noncompetitive inhibitors bind to the enzyme and change the shape of the enzyme. The change in in shape of the enzyme results in the substrate not being able to bind to the enzyme. Competitive inhibitors insert themselves in the active site. Substrates may not bind to an enzyme with a molecule already inhabiting it’s active site. 21  Positive Feedback This is when the final product of a pathway leads to more production. Blood clotting is an example. When fibrin is produced the products of later reactions in crease fibrin construction. This will stop when the clot (or scab) is fully formed, thus switching from a positive feedback to a negative feedback. Not for test: Global Warming is partially a positive feedback loop. As temperature warms it increases in the release of methane gas from the tundra areas. Methane is a greenhouse gas that increases temperature rise. As the temperature continues to rise more methane is released. 22  Transport across membrane Membranes regulate what goes in and out of a cell. Membranes are called selectively permeable structures, which means they allow certain substances the ability to move in and out and block other The substances. chemistry within a cell maybe different Freshly baked brownies create a concentration gradient. In than its surrounding environment. the kitchen there is a higher A different in chemistry leads to a amount of brownie aroma concentration gradient. than in the living room. You often followed this In a concentration gradient a solute is concentration gradient when more dense in one location than you were a child. another location. Diffusion is the spontaneous motion of matter from high concentration to a low concentration. This will occur until the matter is evenly distributed. All forms of membrane transport involve 23 considerations of the concentration  Passive Transport Release Blood cells Passive transport does not require O2 and takes on energy expenditure from the cell. CO2 This form of transport requires CO2 leaves diffusion. Simple diffusion requires no endothelial O2 leaves cell and blood and proteins. Lipids and small non- enters enters the blood cell. endothelial polar covalent bonded structures cells. may passively move through a Increase in CO2 membrane Concentration gradients and decrease in O2 are often kept in one direction, because as a substance moves into the cell then it is Endothelial cells consumed. The exchange of gasses This creates a between hemoglobin continual found in red blood cells concentration and other portions of the gradient which body is a good example. keeps matter flowing 24 in one direction  The dead sea Osmosis The dead sea is hypertonic in comparison to the Mediterranean sea. Osmosis is the motion of water across a selectively permeable membrane. Water will always follow the Mediterranean Sea concentration gradient, so it will always The Mediterranean flow from higher concentration to a lower Sea is hypertonic in concentration. Tonicity is the comparison of solute comparison to the freshwater pond. concentrations between substances. Isotonic is an example of two solutions which have an equal A freshwater pond is balance of solutes hypertonic in Hypertonic is a solution which has comparison to DI water more solutes than another solution Hypotonic is a solution which has less solute than another solution. 25  Tonicities and osmosis affects shapes of cells. Plant cells place in a hypotonic solution absorb water and experience turgor pressure, which helps provide structure for the plant. Cells are experiencing turgor pressure which is the pressured caused by water flowing into the cell. Properly hydrated plant.  Plants cells placed in hypertonic solutions go through plasmolysis and lose water. The plant will wilt. Cells are experiencing plasmolysis, which is caused by water flooding out of the cell. This results in a shrinking of the cell membrane and the central vacuole. This plant has wilted as a result of water loss.  26  Facilitated diffusion Ions and polar covalent cannot pass through the hydrophobic interior of a cell membrane.diffusion is a form Facilitated of passive transport created by proteins which allow for substances to move in and out of the cell following the concentration gradient. Proteins may assist in the motion of water as well. Water is an exception because it is a polar covalent bonded structure which may move across a Proteins called aquaporins as illustrated allow membrane, but for water to more freely move across the sometimes some membrane. 27 assistance is necessary.  Active Transport Sometimes materials must Cells use active be brought in against the transport proteins concentration gradient. which must expend energy to bring solutes in against the concentration gradient. Fig. 4.20 P. 83 The catfish in the picture above lives in a hypotonic environment. The solute concentration is higher in the fish than in the surrounding environment, but it still must get additional solutes. The sodium-potassium pump, moves sodium out of the cell and potassium in the cell. Both go against the concentration gradient and uses ATP 28 energy in the process.  Formation of vesicles for transport The cell membrane can fold inwards creating a pocket which can bring materials into the cell. This is called endocytosis and is used to bring large particles into the cell. The same vesicle can later reform with the membrane removing waste material the cell did not use. 29  Two types of endocytosis Pinocytosis is when a cell takes in a volume of fluid and the solutes within the fluid. It is commonly referred to as cellular drinking. Fig. 4.21 p. 83 Pinocytosis Phagocytosis is when a cell engulfs large particles or even another cell. The vesicle now can fuse with a lysosome which will digest the structure. Phagocytosis 30