2Cells, Matter, and Energy ALL cells need energy and matter for growth and reproduction.Some organisms (like plants) obtain their energy directly from the Sun.Other organisms must consume food to obtain energy.
3PhotosynthesisAutotrophs: self feeders, organisms capable of making their own foodPhotoautotrophs: use photosynthesis = makes organic compounds (glucose) from light. Converts sun energy into chemical energy usable by cells.Chemoautotrophs: use chemosynthesis = makes organic compounds using energy from the oxidation of inorganic chemicals, such as sulfur released from deep hydrothermal vents.
4Thinking About Energy Energy = Capacity to do work Potential Energy = Stored energy (the energy must be released for it to do any work e.g. apple hanging by a stem)Kinetic Energy = The energy of motion (apple falling to the ground)Chemical Energy = Energy stored in the bonds of molecules. Type of potential energy. Once the chemical bonds are broken, the atoms have extra kinetic energy. The atoms can move, do work, make things happen!
6Essential Energy Transformations Photosynthesis = light energy from the Sun is used to transform carbon dioxide and water into energy-rich food molecules.CO H2O C6H12O6 + O2Light EnergyCarbon DioxideWaterGlucoseOxygen
7Essential Energy Transformations 2. Cellular Respiration = all of the chemical reactions needed to break down (metabolize) carbohydrates (and other molecules) to transfer chemical energy to ATP.C6H12O6 + 6O H2O + 6CO2ADPATPCarbon DioxideGlucoseOxygenWater
8What is Photosynthesis? Involves over 100 chemical reactions.The overall process happens in two main stages:1. PHOTO stage: light dependent2. SYNTHESIS stage: light independent
9Photo stage Synthesis stage Splits water and produces ATP.Photosystem reactions need light energy.Stores chemical energy in the bonds of glucose.Synthesis reactions need chemical energy (ATP) and H+ from photo stage.Synthesis stage
14Electromagnetic Spectrum All forms of electromagnetic radiation travel at m/sDifferent frequency of light results in different wavelengths, which are perceived as different colours.The highest frequency of light is violet and the lowest frequency is seen as red.A combination of all of the frequencies is interpreted as White light.
15Photon Model of LightLight travels through space in the form of individual energy “packets” called photons.The amount of energy in a photon depends on the frequency of light. The higher the frequency the more energy the photon is able to deliver.More energy in a photon of violet than in red.
16The Chemistry of Pigments To use the energy of light for photosynthesis, a plant must absorb photons of light.Molecules that absorb light are called Pigments.Most plant leaves contain chlorophyll pigments which give leaves their green colour.Absorption is only one of three possible outcomes when light strikes a surface.The other two are reflection and transmission
18Chlorophyll Photosynthesis takes place in chloroplasts Chloroplasts contain light absorbing pigment molecules (chlorophyll a & b)Chlorophyll absorbs red, violet, and shades of blue.The chlorophyll passes the energy onto other molecules that can be used by the synthesis reactions.
20Chloroplast Structure Very small – 40 chloroplasts in 1mm.Very powerful - perform hundreds of reactions in just 1 second.Has a double membrane.
21Chloroplast Structure Folded THYLAKOID membranes form stacks known as GRANA. The folding increases the surface area for reactions to occur.Inside the thylakoid is a space called the LUMEN
22Chloroplast Structure In and around the grana is a watery substance called STROMAThe chloroplast also contains lots of ENZYMES.
23Light Dependant Reactions Light energy is used to split water molecules (photolysis) to form oxygen and hydrogenOxygen atoms (O2) are released into the atmosphereHydrogen atoms added to NADP to make NADPH+
24Light Dependant Reactions Oxygen molecules pass out the chloroplast membrane into the cell’s cytoplasm.Most of the oxygen that is produced is waste product.The plant’s own cells use some of the oxygen to carry out cellular respiration.
25Photosystem – Light Dependant Reactions Chlorophyll pigments are packed into clusters called PHOTOSYSTEMSPhotosytems funnel absorbed energy to the REACTION CENTER
26Photosystem – Light Dependant Reactions Excited electrons are passed from the primary electron acceptor to ELECTRON TRANSPORT CHAINSThe electrons “fall” to a lower energy state, releasing energy that is harnessed to make ATP.
28ATP Adenosine triphosphate One molecule of ATP contains three phosphate groupsWhen removing the third phosphate group, lots of energy given offAn EXCELLENT molecule for shuttling energy around within cells.
29NADPH Nicotinamide adenine dinucleotide phosphate NADPH is the reduced form of NADP+.Reduction is the gain of electrons by a molecule, atom, or ion
30Light Independant Reactions – Calvin Cycle Does not require sunlightRequires 18 ATP's, 12 NADPH's, and CO2 to produce glucoseUses the products from the Light ReactionOccurs in the STROMA of the chloroplastThree phases of the Dark ReactionCarbon FixationReductionRegeneration
31Light Independant Reactions Carbon fixation is a process which involves the conversion of carbon in a gas to carbon in solid compounds.In order for carbon fixation to occur, energy in the form of ATP and hydrogen (from photolysis) are needed.The carbon can be used to make organic compounds.
32Phase 1 - Carbon Fixation The carbon of a CO2 molecule from the atmosphere is attached to a 5-carbon sugar called RuBPThis forms an unstable 6-carbon compoundThe 6-carbon compound breaks down to form two 3-carbon molecules called PGAL(phosphoglyceraldehyde)Think of PGAL as half a glucose
33Phase 2 - ReductionThe 3 PGAL are converted to G3P using energy (ATP) and hydrogens from NADPH from the Light ReactionFor every 3 molecules of CO2 there are 6 molecules of G3P producedOnly 1 is net gainWhat happens to the other 5?Regeneration
34Phase 3 - RegenerationProducts need to be regenerated to keep the cycle going.5 of the 6 G3P molecules are regenerated using ATP and producing 3 RuBP molecules which are then ready to receive new CO2 and continue the cycleThe one G3P molecule combined with another G3P molecule is used to make glucose, fructose, sucrose, starch and cellulose for the plant.
36Rate of Photosynthesis Describes how much sugar a plant can produce over timeIt describes how productive a plant is under various conditionsWhat things would control the rate of photosynthesis?
37Rate of Photosynthesis 1. Light Intensity:High Intensity Light causes the rate of photosynthesis to increaseThe rate will increase until it reaches its saturation pointAt the saturation point, the rate of photosynthesis remains constant
38Rate of Photosynthesis 2. Temperature:As temperature increases, so does the rate of photosynthesisEnzymes function at an optimal temperature: If the temperature is too high or too low, enzymes will not function properlyRate of photosynthesis will slow down or stop.
39Rate of Photosynthesis 3. Water:Water is one of the raw materials of photosynthesisA shortage of water can slow or even stop photosynthesisWater stress causes stomata to close, preventing CO2 from entering the leaf
40Rate of Photosynthesis 4. Carbon Dioxide:An increase in CO2 concentration causes the rate of photosynthesis to increaseMore CO2 available means more sugar made in the light independent reaction
41Plants AdaptationsIn hot, dry environments plants maximize photosynthesis by limiting water loss.Leaves of plants contain stomata which are tiny holes in the leaves that release by products and take in raw materials need for photosynthesis
42Plants AdaptationsMost plants will close their stomata to prevent water loss but this limits carbon dioxide intakeSome plants will only open the stomata during nightIt is a fine balance between receiving the necessary supplies and preventing water loss.
43Plants AdaptationsIf the CO2 concentration in the cell drops below 50 ppm, the cell begins to undergo PHOTORESPIRATION which results in the fixation of oxygen instead of carbon dioxide.This is a very wasteful process as it produces a substance that is not useful to the cycle.