Chapter 8 Energy From Sunlight Photosynthesis Cellular Respiration

Chapter 8 Energy From Sunlight

Photosynthesis / Cellular Respiration Recycle a common set of chemicals: • Water • Carbon Dioxide • Oxygen • Glucose (Organic Compounds)

Food and Chemical Energy • Energy – The ability to do work Work = whenever an object is moved versus an opposing force

Two Types of Energy 1. Kinetic Energy – energy in motion • Anything Moving • Although, energy can’t be created or destroyed it can be converted from one form to another • Stop moving

Two Types of Energy 2. Potential Energy – Energy that is stored due to an objects position or arrangement • The higher you go against the force of gravity the more potential energy your body has. • As you fall; that is kinetic energy

Potential Energy Abby Wambach U. S Soccer

Thermal Energy The total amount of energy associated with the random movement of atoms and molecules in a sample of matter • The transfer of energy from a warmer object to a colder one

Chemical Energy • The potential to perform work is due to the arrangement of the atoms within the molecules • So structure and chemical make-up = energy • Rearrangement of atoms during a chemical reaction releases potential energy. • After this breakdown; smaller molecules have less energy than the original molecule.

Chemical Energy Note: Some energy is lost as heat • Easy to see in a car; “internal combustion” engine • In our bodies our cells are more efficient plus some heat is used by our bodies to maintain a constant body temperature.

Calories: Unit of Energy • The amount of energy required to raise the temperature of 1 gram of water by 1° C • When measuring calories in food is actually measure in kilocalories because one calorie is SO small. • Calories are measured in a lab by burning foods and measuring the increase in temperature in water.

The Energy in Food ATP – Adenosine Triphosphate • Cells in plants and animals use ATP as their main energy supply

ATP Adenosine Triphosphate Adenosine – A Nitrogen Compound + Ribose – a five carbon sugar + Triphosphate tail – 3 phosphate groups • This is where energy is taken from

ATP • Each Phosphate group is negatively charged • Bonded by a Phosphate Bond • Remember “like” charges repel; that “forced” bond acts like a coiled spring = potential energy • Break the phosphate bond (release) spring energy is released.

ATP Cycle • In most cases: one phosphate bond is broken • Left with two phosphate groups • Adenosine Diphosphate (ADP)

ATP Cycle ATP can be recycled; Requires energy • A working muscle recycles all its ATP in one minute • Break between sets when working out.

Cellular Work • During a chemical reaction that breaks one of the ATP’s bonds, the phosphate group is transferred from ATP to another molecule • Specific enzymes enable this transfer • Molecule that accepts phosphate undergoes a change; driving the work

3 Types of work that Cells Perform 1. Chemical Work • Building large molecules like proteins • ATP provides energy for Dehydration Synthesis

3 Types of work that Cells Perform 2. Mechanical Work • Muscle Contraction • ATP causes change in shape of protein which then opens the door for Potassium (K) and Calcium (Ca) to cause the binding of Actin and Myosin.

3 Types of work that Cells Perform 3. Transport Work • Pumping Ions across a membrane

Pigments Sunlight is a form of electromagnetic energy • Electromagnetic energy travels in waves Wavelength – The distance between two adjacent waves • Different forms of electromagnetic energy have their own wavelength.

Electromagnetic Spectrum • The range of types of electromagnetic energy; from the very short wavelength (gamma rays) to the very long wavelength (radio waves) TV Show Alphas

Pigment and Color • Chloroplast DO NOT absorb green very well • Green light bounces off leaf • Leaf is green because green light is not absorbed

Visible Light ROYGBIV

Visible Light • Those wavelength that your eyes can see as different colors • Make a small fraction of the electromagnetic spectrum • Shorter wavelengths have more energy than longer wavelengths (violet/indigo) • Actually shorter wavelengths can damage organic molecules like proteins and nucleic acids • This is why U. V. rays cause sunburns and can lead to skin cancer

Pigment and Color Pigment – chemical compounds in a substance that determines color 1. 2. 3. • Three Things That Happen to Wavelengths Absorbed Transmitted Reflected Pigments in the leaf’s chloroplast absorb blue-violet and red very well

Photosynthesis The process by which plants and other producers convert the energy of sunlight into the energy stored in organic molecules.

Leaf Structure Design allows leaf to act like a solar panel

Chloroplast • The organelle where photosynthesis takes place Chlorophyll – A chemical found in chloroplast, that gives green color. • In a plant when you see green; photosynthesis is occurring. • Most plants it is in their leaves.

Types of Chlorophyll Pigments Chlorophyll a – absorbs mainly blue-violet and red light; reflects green light • Plays a major role in photosynthesis Chlorophyll b – (helper pigment) absorb mainly blue and orange light; reflects yellow-green Carotenoids – (many types) absorb mainly bluegreen light; reflect yellow-orange

Types of Chlorophyll Pigments

Chloroplast Mesophyll – areas where chloroplast are concentrated (on a leaf); inner layer of tissue • Palisade Mesophyll – layer on the top side of the leaf to collect as much sunlight as possible • Spongy Mesophyll - A leaf tissue consisting of loosely arranged, chloroplast-bearing, usually lobed cells.

Chloroplast

Chloroplast Stomata – (stoma singular) are tiny pores found at the surface of the leaf. • CO₂ enters; O₂ leaves these sites, along with H₂O. • Veins carry water and other nutrients from the plant roots to the leaves • Veins also carry organic molecules made on the leaf to where it is needed.

Mesophyll & Stomata

Chloroplast • structure is key to function Stroma – thick fluid enclosed by inner membrane • Look at Sroma like a thick version of cytoplasm Thylakoids – disk shaped sacs in stroma • Each thylokoid has membrane surrounding an interior space Grana – (singular granum) stacks of Thylakoids. • These structures all organize the series of chemical reactions that make up photosynthesis • Like in cellular respiration some happen interior (thylakoid) while other occur in the stoma; outside

Chloroplast Photosystems – in the thylakoid membrane; clusters of chlorophyll and other molecules • Contain a few hundred pigments chlorophyll a/b and carotenoids • Cluster of pigments acts like a light gathering panel • Like a mini-solar panel.

Chloroplast

Photosynthesis • Opposite reaction of cellular respiration • eˉ form water go “uphill” using energy from the Sun. • Chloroplast use these electrons with carbon dioxide and H ions to produce sugar molecules.

Photosynthesis Two Main Stage I Light Reaction • Convert the energy in sunlight to chemical energy 1 st – Chlorophyll molecules in the membrane capture light energy 2 nd – Chloroplast use energy to remove eˉ from water • This splits H⁺ + O₂ • O₂ is the “waste product” for photosynthesis

Light Reaction • O₂ escape into the atmosphere via the stoma (on leaves) 3 rd – Chloroplast use H₂O eˉ and H⁺ ions to (make energy rich molecules) NADPH 4 th – (finally) ATP is made in chloroplast Results of Light Reaction – NADPH + ATP

Light Reaction

Harvesting Light Energy • Each time a pigment absorbs light energy 1 of the pigments eˉ gains energy • eˉ goes from a low energy state to a high enegry state. • This “excited” state is unstable • Almost immediately the excited eˉ fall back down to a low energy state transferring the energy to a neighboring molecule • And so on to the next

Harvesting Light Energy • Energy continues to jump from molecule to molecule till it reaches the reaction center of the photosystem • Contains chlorophyll a and PEA

Harvesting Light Energy Primary Electron Acceptor – a molecule (located in the reaction center) that traps the excited electron from the chlorophyll a molecule • Now other molecules in the thylakoid membrane can use trapped energy to make ATP/NADPH

Products of Light Reactions • Two photosystems are involved in light reactions • The First photosystem traps light energy and transfers the light excited eˉ to an electron transport chain. • AKA – Water – Splitting Photosystem • Released O₂ as waste and release H ions

Products of Light Reactions • The eˉ transport chain connecting the two photosystems releases energy which chloroplast use to make ATP • It is very similar reaction to cellular respiration • An electron transport chain pumps hydrogen ions across a membrane • In mitochondria it is the inner membrane (cellular respiration) • In the thylakoid membrane in photosynthesis

Products of Light Reactions • The second photosystem produces NADPH by transferring excited eˉ and H ions to NADP⁺ Light Reactions Produce – ATP and NADPH ATP NADPH

Products of Light Reactions • Main difference is that in respiration food provides the eˉ for the electron transport chain • In photosynthesis light-excited eˉ for the electron transport from chlorophyll travel down the chain. (P 680/P 700 are pigments)

Photosynthesis Stage II The Calvin Cycle • Makes sugar from the atoms in CO₂ + the H ions and high-energy eˉ carried by NADPH • Enzymes for the Calvin Cycle are located outside thylakoids and are dissolved in the stoma • ATP made in Light Reaction provides energy to make sugar • Calvin Cycle AKA “Light Independent Reactions” because it does not require light to begin reaction

The Calvin Cycle • Material is regenerated each time the process occurs • 5 Carbon sugar: Ru. BP • It’s the compound that gets regenerated 1 st – Carbon enters the cycle as 3 CO₂; an enzyme adds a molecule to a Ru. BP molecule – forming 3 unstable 6 Carbon molecules 2 nd – The (3) 6 C molecules break immediately into 6 3 -carbon molecules called 3 -PGA

The Calvin Cycle 3 rd – At this point: ATP/NADPH (from light reaction) provides energy and eˉ that are used to convert the 3 -PGA to G 3 P the Direct Product of Photosynthesis. 4 th – Carbon exits in one molecule of G 3 P to make glucose and other compounds 5 th – 15 Carbon atoms remain in 5 -G 3 P molecules 6 th – ATP provides the energy used to rearrange G 3 P molecules and Regenerate Ru. BP and ADP and NADP → sent back to the light reaction

Calvin Cycle

The Calvin Cycle

Photosynthesis Summary Light Reaction – takes place in the thylakoid membrane • Convert light energy to chemical energy (ATP) and NADPH Calvin Cycle – takes place in the stroma; uses ATP and NADPH to convert CO₂ to sugar.

Photosynthesis Summary First Step in the Flow of Energy in a Ecosystem

Factors that affect Photosynthesis • • Carbon dioxide uptake p. H Temperature Water