Photosynthesis Chapter 8 Light energy 6 CO2 + 6 H2O C6H12O6 + 6 O2 Carbon dioxide Water Glucose Oxygen gas Photosynthesis Photosynthesis Chapter 8

Do you remember any of the eight characteristics of living things? Living things are based on a universal genetic code (DNA) Living things grow and develop Living things respond to their environment (stimulus) Living things reproduce Living things maintain a stable internal environment (homeostasis) Living things obtain and use material and energy (metabolism) Living things are made up of CELLS Taken as a group, living things evolve over time

Three Subatomic Particles Proton: (+) charged particle found inside the nucleus Neutron: neutral particle found inside the nucleus Electron: (-) charged particle found outside the nucleus in various energy levels

Organic Compounds Carbohydrates Lipids Proteins Nucleic Acids Monomer: Monosaccharide Made up of: Carbon, Hydrogen, Oxygen (H:O in 2:1 ratio) Sugars – glucose, fructose, sucrose Lipids Glycerol and Fatty Acids (H:O not in 2:1 ratio) Oils, Waxes, Butter Proteins Amino Acid Carbon, Hydrogen, Oxygen, Nitrogen Enzymes Nucleic Acids Nucleotide 1) 5 Carbon sugar, 2) phosphate group 3)nitrogenous base Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus DNA and RNA

Differences between plant and animal Cell wall Chloroplast Photosynthesis Lysosomes only in specialized cells No centrioles No cell wall No chloroplast No photosynthesis Lysosomes Centrioles (cell division)

Organelle for photosynthesis – chloroplast Organelle to convert chemical energy into energy the cell can use – mitochondria Energy currency of the cell – ATP Why are plants green? Chlorophyll

Autotrophs and Heterotrophs: Organisms that manufacture their own food (Plants) Also known as producers Heterotrophs Organisms that cannot make their own food (Humans) Also known as consumers

Autotrophs and Photosynthesis: Autotrophs use the energy directly from sunlight and store it in organic compounds. They convert solar energy to chemical energy stored in carbohydrates (glucose). Photosynthesis is a series of complex reactions in which the product of one reaction is consumed in the next reaction. A series of reactions linked in this way is called a biochemical pathway.

Biochemical Pathway:

Equations: Photosynthesis: (stores energy) 6 CO2 + 6 H2O  C6H12O6 + 6 O2 Cellular Respiration: (releases energy) C6H12O6 + 6 O2  6 CO2 + 6 H2O + ATP glucose glucose

Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2 Carbon Dioxide Glucose Water LIGHT 6CO2 + 6H2O C6H12O6 + 6O2 Carbon Dioxide Glucose Water Oxygen

What is Light? Which type of light carries more energy, blue or red? Light travels through space as waves of energy. Different colors have different wavelengths. Which type of light carries more energy, blue or red? Light Speed, c = 2.9979 x 108 m/s or 670.6 million mph

Electromagnetic Spectrum Wave length and energy are inversely proportional The smaller the wave length, the more energy Blue light is high energy Red light is low energy Why are plants usually green? They reflect green light

Takes place in the chloroplast Photosynthesis Takes place in the chloroplast Thylakoids – saclike photosynthetic membrane in the chloroplast Grana – stacks of thylakoids Stroma - the region outside of the thylakoid membranes

Plant (Chloroplast) Pigments Membranes of the thylakoid contain a variety of pigments Pigments – light absorbing molecules Chlorophyll – the most abundant pigment in plants that absorbs blue and red light. Chlorophyll a - blue-green pigment Chlorophyll b - yellow-green pigment

Accessory Pigments – absorb light in other regions of the spectrum Carotene - an orange pigment Xanthophyll - a yellow pigment Anthocyanin – a red pigment

Accessory Pigments Why do plants need accessory pigments? They absorb light in other regions of the spectrum The accessory pigments are always present in most plants but masked by the chlorophyll.

Pigments Why do leaves change color in the fall? Answer: Shorter day lengths stop chlorophyll production, and expose accessory pigments

Chemical Energy and ATP: One of the most important compounds that cells use to store and release energy is adenosine triphosphate (ATP). ATP consists of adenine, a 5-carbon sugar called ribose, and three phosphate groups.

Why is ATP useful to cells? ATP can easily release and store energy by breaking and re-forming the bonds between its phosphate groups. This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells. ATP Synthase (3:21)

ADP and ATP Cells store energy by adding a phosphate group to adenosine diphosphate (ADP) molecules Cells release energy from ATP molecules by subtracting a phosphate group The energy of ATP is locked in the bonds between the phosphate groups. When the terminal phosphate group of the ATP molecule is removed by hydrolysis, energy is released and adenosine diphosphate (ADP) and phosphate are formed. ATP Synthase (3:21)

Photosynthesis (Overall) Light CO2 H2O Chloroplast LIGHT REACTIONS (in thylakoids) CALVIN CYCLE (in stroma) NADP+ ADP + P ATP NADPH O Sugar Electrons Dark Light

An Overview of Photosynthesis: Because light is a form of energy, any compound that absorbs light absorbs energy. Chlorophyll absorbs visible light especially well. When chlorophyll absorbs light, a large fraction of the light energy is transferred to electrons. These high-energy electrons make photosynthesis work. Photosynthesis (3:39)

Light-Dependent Reactions: Photosynthesis involves two sets of reactions. The first set of reactions is known as the light- dependent reactions because they require the direct involvement of light and light-absorbing pigments.

Light-Dependent Reactions: The light-dependent reactions use energy from sunlight to produce energy rich compounds, like ATP and NADPH. Water is required and Oxygen is a byproduct These reactions take place within the thylakoid membranes of the chloroplast.

Light-Independent Reactions (Calvin Cycle): Plants absorb carbon dioxide from the atmosphere and complete the process of photosynthesis by producing sugars and other carbohydrates. During light-independent reactions, ATP and NADPH molecules produced in the light-dependent reactions are used to produce high-energy sugars from carbon dioxide.

Light-Independent Reactions: No light is required to power the light-independent reactions. The light-independent reactions take place outside the thylakoids, in the stroma.

An Overview of Photosynthesis: CO2 Sunlight O2 Sugars (C6H12O6) 6 CO2 6 H2O 6 O2 C6H12O6 _____ + _____  _____ + _____ Photosynthesis Overview (7:26)

Rate of Photosynthesis: Light Intensity: Increase rate of photosynthesis, then levels off (maximum rate of photosynthesis) Higher intensity, excites more electrons in chlorophyll @ some intensity, all available electrons are excited

Rate of Photosynthesis: Temperature: Higher temperature accelerates the chemical reactions. Peaks @ certain temperature because the enzymes become ineffective and unstable

Rate of Photosynthesis: Amount of CO2: Increases rate of photosynthesis to a point, then levels off Water Availability:

Biochemical Pathway:

Structure of the Chloroplast

Chemical Energy and Food PHOTOSYNTHESIS ___________ + _________ + ___________ →_______________ + __________ 6 CO2 6 H2O C6H12O6 6O2 CELLULAR RESPIRATION C6H12O6 6 CO2 _____________ + _________ →________ + __________ + __________ 6O2 6 H2O The two equations are exact opposites!

Structure of the Mitochondria:

Cellular Respiration Chapter 9

Comparing Photosynthesis & Cellular Respiration: Function Location Reactants Products Produces food (chemical energy) for the plant (glucose C6H12O6) Produces chemical energy (ATP) for the cell Chloroplast Mitochondria Water (H2O), Carbon dioxide (CO2) and sunlight Oxygen (O2) and Glucose (C6H12O6) Water (H2O), Carbon dioxide (CO2) and energy (ATP) Oxygen (O2) and Glucose (C6H12O6)

Comparing Photosynthesis & Cellular Respiration: Which type(s) of organisms carry out photosynthesis? Autotroph Heterotroph Which type(s) of organisms carry out cellular respiration?

Chemical Energy and Food Cellular respiration happens slowly and in many steps. If all the energy was release in one step… Most would be lost as light and heat! Cellular respiration breaks down glucose molecules and banks their energy in ATP

An Overview of Cellular Respiration:

Stages of Cellular Respiration: The three main stages of cellular respiration are Glycolysis Krebs cycle Electron transport chain.

Oxygen and Energy: Pathways of cellular respiration that require oxygen are called aerobic. The Krebs cycle and electron transport chain are both aerobic processes. Both processes take place inside the mitochondria.

Oxygen and Energy: Glycolysis and fermentation are anaerobic processes. They do not directly require oxygen, nor do they rely on an oxygen- requiring process to run. However, glycolysis is still considered part of cellular respiration. Glycolysis takes place in the cytoplasm of a cell.

Compare Photosynthesis to Cellular Respiration NADH FADH2 GLYCOLYSIS Glucose Pyruvate CITRIC ACID CYCLE OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) Substrate-level phosphorylation Oxidative phosphorylation Mitochondrion and High-energy electrons carried by NADH ATP CO2 Cytoplasm Compare Photosynthesis to Cellular Respiration Light CO2 H2O Chloroplast LIGHT REACTIONS (in thylakoids) CALVIN CYCLE (in stroma) NADP+ ADP + P ATP NADPH O Sugar Electrons How Cells Obtain Energy (14 min)