Energy for Living Systems

Energy for Living Systems

Energy for Living SystemsEnergyAbility to do work

Types of energy Potential Energy Energy of position For living organisms, potential energy is stored in chemical bonds Kinetic EnergyEnergy of motion Breaking of chemical bonds in various life processes. Activation Energy Energy necessary to trigger a chemical reaction Lighted match held to a piece of paper

EnergyAll living things require energy. Necessary for carrying out all life processes - building, repairing, growing, and reproducing. Energy comes from food (glucose) Energy is stored in glucose bonds - potential energy No organism can make energy - comes from the sun. Law of Conservation of Energy -Energy can be neither created nor destroyed, but can only be changed from one form to another. EnergyOrganisms divided into 2 groups according to the way they get their food. Autotrophs organisms that can combine inorganic molecules into organic molecules for use as food; make their own food Heterotrophs - organisms that don't make their own food but depend directly on other organisms for food.

EnergyEnergy is not recycled, matter is recycled Energy available for use decreases with each transformation Some of the energy used to break bonds and some is lost as heat. New energy must be constantly supplied - must come from sunlight. Materials used in producing new molecules can be reused.

EnergyEnergy processes of living organisms

Photosynthesis Process in which carbon dioxide and water is used to form glucose. Requires light energy from the sun. Takes place in the presence of chlorophyll. Respiration Process in which glucose molecule is broken down and chemical energy it contains is released. Carbon dioxide and water released. Performed by all cells - releases energy of foodAdenosine TriphosphateUsable energy from by one reaction may be stored by another molecule and used in a later reaction.

Many times the storage molecule for the released energy is ATP. Adenosine TriphosphateComposed of 3 parts Adenine - a nitrogen base Ribose - a 5-carbon sugar Three (3) phosphate groups

Adenine joins with ribose to form adenosine Phosphate groups attach in sequence to adenosine Adenosine monophosphate - AMP - 1 phosphate group Adenosine diphosphate - ADP - 2 phosphate groups Adenosine triphosphate - ATP - 3 phosphate groups

Adenosine Triphosphate

Adenosine TriphosphateHigh energy bonds form between the phosphate groups - indicated by a wavy line (~)

Requires a great deal of energy to form bond. Energy is released when bond is broken.

ATP - A - P ~ P ~ P

ADP - A - P ~ P

Adenosine TriphosphateNormally reaction is cyclic - moves between ADP and ATP Controls the cell's production through cycle of energy storage and release. ADP + P + energy ---> ATP - energy is stored ATP ---> ADP + P + energy - energy is released Normally cell does not use ADP as energy source; ADP not converted to AMPPhotosynthesisProcess by which green plants convert the sun's light energy into chemical energy stored as food in the form of glucose.

Photo - means "light" Synthesis - means "to build a complex substance from simple substances"

PhotosynthesisRaw materials - the reactants of the reaction Carbon dioxide - CO2 Water - H2O Light energyPhotosynthesisProducts

Glucose - C6H12O6 Oxygen - O2 Water - H2OPhotosynthesisChlorophyll is necessary

Acts as a catalyst - causes the reaction to move forward.Pigment in green plants that gives them their color Primary light absorbing pigment of green plants.

PhotosynthesisRepresented by the following reaction:

chlorophyll 6 CO2 + 12 H2O + light -----------> C6H12O6 + 6 O2 + 6 H2O

PhotosynthesisProcess is series of reactions that change reactants to the products - divided into 2 main reactions

Light Reactions - require light energy Dark Reactions - Do not require light energyLightSunlight is white light; mixture of different wavelengths of light Each wavelength of light has a characteristic color - Colors that make up white light can be separated by prism to produce the visible part of the spectrum - ROYGBIV Red, Orange, Yellow, Green, Blue, Indigo, Violet Shorter the wavelength of light, the more energy it hasBlue shorter wavelengths; more energyRed longer wavelengths; less energy

Light

LightObjects appear to be a certain color because they transmit or reflect light of that color.

Colors absorbed by an object are not seen Color of object is the wavelength of light that is reflected or transmitted by the object. Plants appear green because they reflect green light and absorb other colors of light.

Light Absorption by Green Plants

Plant PigmentsPrimary pigment in plants that absorbs light energy is chlorophyll Green in color - reflects green wavelengths Absorbs mainly red and blue wavelengths of light Act as catalysts to speed the reaction of photosynthesis. Types Chlorophyll a Chlorophyll b Chlorophyll cChlorophyll d Bacteriochlorophyll

Plant PigmentsAccessory Pigments - may be used to transfer some energy to chlorophyllTypesCarotenoids - yellow, brown and orange pigments of plantsCaroteneXanthophyllPhycobilins - accessory pigments of red algae and blue-green bacteriaNot normally visible in tree leaves - masked by chlorophyll; appear when chlorophyll production ceases

ChloroplastsOrganelle in plant cells where photosynthesis occurs. Contain the Chlorophyll pigment. Structure Grana - tiny stacked structures in the chloroplasts Contains the chlorophyll Also contains the accessory pigments. Site of light reactions Stroma - protein-rich solution around the grana Site of dark reaction

Chloroplasts

Light ReactionsChlorophyll traps the light energy Causes chlorophyll molecules to become energized; electrons released from molecule Two different photosystems active in photosynthesis Photosystem I Photosystem II Water molecules are split and oxygen is released. Energy is stored in ATP and NADPH2 (electron acceptor) Both used in the Dark Reactions Supply the energy for the Dark Reactions

Light Reactions

Dark ReactionsLight is not required; energy comes from ATP and NADPH2; Called the Calvin cycleCarbon dioxide bonds to 5-carbon sugar called ribulose diphosphate, RuDP - forms unstable 6-carbon compound6-carbon compound immediately breaks down into two 3-carbon molecule of phosphoglyceric acid, PGA.Each PGA reacts with hydrogen atoms in NADPH2 to produce 3-carbon molecule of phosphoglyceraldehyde, PGAL, water reformedTwo molecules of PGAL combine to produce glucose molecule.Some PGAL used to reform RuDP.

Dark Reactions

RespirationProcess in which cells take energy, stored in chemical bonds of food and incorporates it into chemical bonds of ATP Occurs in the mitochondria Series of chemical reactions

RespirationReactants Glucose - C6H12O6 Oxygen - O2RespirationProducts Carbon dioxide - CO2 Water - H2O ATP - adenosine triphosphate

RespirationOverall equation of cellular respiration (aerobic)

enzymesC6H12O6 + 6 O2 ----------> 6 CO2 + 6 H2O + 36 ATP

RespirationTypes Anaerobic Respiration - doesn't require oxygen Aerobic Respiration - requires oxygen

Stages of Aerobic RespirationGlycolysis - Anaerobic

Krebs (Citric Acid)Cycle - Aerobic

Electron Transport Chain - AerobicGlycolysisFirst stage of respiration; occurs outside the mitochondriaDoes not require oxygen.Glucose breaks down into two 3-carbon molecules of pyruvic acidRequires 2 molecules of ATP to supply activation energyProduces 4 molecules of ATP; net gain of 2 ATP'sPyruvic acid can go in two directions - depends on of organism type and oxygen availabilityAerobic respiration - oxygen requiredAnaerobic respiration - oxygen not neededGlycolysis

Transition to Aerobic Respiration

Aerobic PhasesDivided into two major reactions

Citric acid cycle (Krebs Cycle) Electron Transport ChainCitric Acid CyclePyruvic acid loses a carbon dioxide forms 2-carbon molecule that enters cycle.

Process takes place in the mitochondria

Hydrogen atoms released during the cycle - will carry electrons to the next reactions

2 molecules of ATP are produced

Citric Acid Cycle

Electron Transport ChainInvolves a series of electron acceptors Accepts electrons and H ions from NADH &FADH24 hydrogen atoms produce 24 electrons and 24 hydrogen ions form 12 pairs of hydrogen ions and 12 pairs of electrons Near end of chain 12 molecules of hydrogen bond with 6 oxygen molecules to produce 12 molecules of water. 32 molecules of ATP produced

Electron Transport Chain

Summary of ATP ProductionIn Aerobic RespirationGlycolysis 2 ATP Citric Acid Cycle 2 ATP Electron Transport 32 ATP Total 36 ATP

Anaerobic RepirationOccurs when cell obtains energy from breakdown of food molecules in the absence of oxygen Also known as FermentationFirst step similar to aerobic respiration - glucose converted to pyruvic acid - glycolysis Types of Fermentation Alcoholic Fermentation Lactic Acid FermentationAlcoholic FermentationPyruvic acid is converted to ethyl alcohol Most of the energy is still stored in the alcohol.Summary equation: enzymesC6H12O6 ----------> 2 C2H5OH + 2 CO2 + 2 ATP

Industries that depend on alcoholic fermentation Baking - carbon dioxide; makes bread rise. Brewing - ethyl alcohol in alcoholic beveragesAlcoholic Fermentation

Lactic Acid FermentationOccurs in muscle tissue especially during heavy exercise Blood can't bring oxygen fast enough; lactic acid builds up causing soreness (cramps); muscles go into oxygen debt. Summary equation:

enzymes C6H12O6 -----------> 2 CH3CHOHCOOH + 2 ATP

Lactic Acid Fermentation