PHOTOSYNTHESIS & RESPIRATION. Photosynthesis & Respiration Modern Biology –Photosynthesis / Chapter 6 –Cellular Respiration / Chapter 7

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PHOTOSYNTHESIS & RESPIRATIONPhotosynthesis & RespirationModern BiologyPhotosynthesis / Chapter 6 Cellular Respiration / Chapter 7

Energy for Life ProcessesAll organisms need energy to survivePrimary source of energy is the sun.

Energy is the ability to do work Work for a cell includes growth & repair, active transport across cell membranes, reproduction, synthesis of cellular products, etc.

When you kick a ball, you are using energy. When you talk, you are using energy. All the activities you do require energy. Question: What is Energy?

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Most organisms need a constant supply of energy.

Energy can be found in many forms.

Energy from the sun is in the form of light energy.

Energy in food is in the form of chemical energy.

Energy for Life ProcessesHumpback whales need a lot of energy to leap into the air.

Energy comes fromthe food that they eat.

How much food doyou think a humpbackwhale can eatin one day?

4Energy for Life ProcessesHow do organisms get this energy from the sun?

PHOTOSYNTHESIS-process used by plants to convert energy from the sun to food (glucose).RESPIRATION-process that releases energy in food (glucose) to make energy (ATP).

When you kick a ball, you are using energy. When you talk, you are using energy. All the activities you do require energy. Question: What is Energy?

5Energy for Life ProcessesAutotrophic self-feeding

Autotrophs or producers convert sunlight, CO2, and H2O into glucose (their food).This process is called PHOTOSYNTHESIS Plants, algae, and blue-green bacteria, some prokaryotes, are producers or autotrophs .

When you kick a ball, you are using energy. When you talk, you are using energy. All the activities you do require energy. Question: What is Energy?

6Autotrophs

PlantsAlgae & some bacteria

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Energy for Life ProcessesOnly 10% of the Earths 40 million species are autotrophs Some other autotrophs use inorganic compounds instead of sunlight to make food; process known as chemosynthesis Producers make food for themselves and for heterotrophs or consumers that cannot make food for themselves

In biochemistry, chemosynthesis is the biological conversion of one or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e.g. hydrogen gas, hydrogen sulfide) or methane as a source of energy, rather than sunlight, as in photosynthesis.Many microorganisms in dark regions of the oceans also use chemosynthesis to produce biomass from single carbon molecules. 8Heterotrophic other-feedingAnimals (including humans) represent heterotrophic organisms.Since they cannot make their own food, humans and other heterotrophs must get their complex organic compounds by eating plants or other organisms.

Animals and Fungi9Once you eat something, the food gets broken down into nutrients, or smaller molecules the cells can use.

Some of these molecules are in the form of sugar (glucose). The bonds that hold these molecules together contain energy.

Photosynthesis & RespirationCells absorb broken food pieces (macromolecules such as protein, nucleic acid, carbohydrates, lipids). In the form of monomers ( building blocks, such as amino acids, glucose & fructose, nucleotides and some smaller pieces of lipids.).

10Cellular respiration is the process that turns food into ATP, a form of energy that our cells can use.

Photosynthesis & Respiration

11Energy for Life Processes

Biochemical PathwaysPhotosynthesis and cellular respiration are biochemical pathways Biochemical pathways are a series of reactions where the product of one reaction is the reactant of the next Only autotrophs are capable of photosynthesis Both autotrophs & heterotrophs perform cellular respiration to release energy to do work

13Biochemical PathwaysIn photosynthesis, CO2(carbon dioxide) and H2O (water) are combined to form C6H12O6 (glucose) & O2 (oxygen)6CO2+ 6H2O + energy --> 6O2 + C6H12O6 In cellular respiration, O2 (oxygen) is used to burn C6H12O6 (glucose) & release CO2(carbon dioxide) , H2O (water) and energy Usable energy produced in cellular respiration is stored in the chemical bonds of the molecule adenosine triphosphate or ATP

14Biochemical Pathways

PhotosynthesisCellular Respiration15

Biochemical Pathways

16PHOTOSYNTHESISA series of chemical reactions (light & dark reactions and the Calvin Cycle) where autotrophs capture light energy to make food (glucose).

Chemical Formula:6CO2 + 6H2O + sunlight C6H12O6 + 6O2Carbon Dioxide water sunlight glucose and oxygen

18Leaves: Photosynthetic FactoriesPhotosynthesis requires the green pigment chlorophyll. The chemical reactions of photosynthesis occur within the chlorophyll-containing organelles called chloroplasts.These are found inside cells in plant leaves and stems.

Chlorophylls chemical structure has the potential to gain or lose electrons easily, which is what allows it to absorb photons and transfer the excitation energy to and within the photosynthetic reaction center.19

Chloroplasts - membrane bound organelles found in plant and algae cells that absorb light during photosynthesis

They contain:1. the light absorbing pigments2. enzymes for photosynthesisLight Absorption in Chloroplasts

Light Absorption in ChloroplastsPhotosynthetic cells may have thousands of chloroplasts Chloroplasts are double membrane organelles with the an inner membrane folded into disc-shaped sacs called thylakoids

21Light Absorption in ChloroplastsThylakoids, containing chlorophyll and other accessory pigments, are in stacks called granum (grana, plural) Grana are connected to each other & surrounded by a gel-like material called stroma Light-capturing pigments are found in the grana.

During photosynthesis, the cells in green plants undergo two simultaneous reactions, both of which rely on a separate kind of protein. Photosystem I protein molecules use the trapped energy in sunlight to convert carbon dioxide into carbon and oxygen. This provides the plant food in the form of carbohydrates, lipids, proteins and nucleic acids - the building blocks of life. Photosystem II protein molecules use light energy to split water into hydrogen and oxygen for plant respiration.22Light Absorption in Chloroplasts

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Light Absorption in ChloroplastsHow do chloroplasts absorb light??

LIGHT:

Light travels as waves & packets called photons Wavelength of light is the distance between 2 consecutive peaks ortroughs

During photosynthesis, the cells in green plants undergo two simultaneous reactions, both of which rely on a separate kind of protein. Photosystem I protein molecules use the trapped energy in sunlight to convert carbon dioxide into carbon and oxygen. This provides the plant food in the form of carbohydrates, lipids, proteins and nucleic acids - the building blocks of life. Photosystem II protein molecules use light energy to split water into hydrogen and oxygen for plant respiration.24

Light Absorption in ChloroplastsSunlight or white light is made of different wavelengths or colors carrying different amounts of energy

A prism separates white light into 7 colors (red, orange, yellow, green, blue, indigo, & violet)ROY G BIV

These colors are called the visible spectrum

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Light Absorption in ChloroplastsThe visible spectrum

Each color in a rainbow corresponds to a different wavelength of electromagnetic spectrum.

light is funky and acts like it has both particles and waves? A photon is what we call the particle-like aspect of light. In other words, a photon is the basic unit of light.

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Light Absorption in ChloroplastsWhen light strikes an object, it is absorbed, transmitted, or reflected When all colors are absorbed, the object appears black

When all colors are reflected, the object appears white

If only one color is reflected (green), the object appears that color (e.g. Chlorophyll)27Thylakoids contain a variety of pigments molecules that absorbs light - (green, red, orange, yellow...)

Chlorophyll is themost commonpigment in plants & algae

Chlorophyll absorbsonly red, blue, & violet light Light Absorption and Pigments

28Accessory pigments trap wavelengths of light that can not be absorbed by chlorophyll - help capture more light energy

Carotenoids reflect orange, yellow, and brown and absorbs green and bluePhycobilins reflect violet & blue and absorb orange, brown and greenLight Absorption and PigmentsIn the leaves of a plant the chlorophyll is much more abundant and therefore mask the colors of the other pigments. In the non-photosynthetic part of the plant, such as the fruits and flowers, the colors of the other pigments are quite visible. During the fall many plants loose their chlorophylls and the leaves take on the rich hues of the caratenoids.29

Photosynthesis is not a simple one step reaction but a biochemical pathway involving many steps.

This complex reaction can be broken down into two reactions:1. light dependent (Photosystem I & II, Electron Transport Chain)2. light independent or dark reactions (The Calvin Cycle)Overview of Photosynthesis32Overview of Photosynthesis

33Overview of Photosynthesis

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Plants in hot, dry climates use alternate pathways to fix carbon.

Stomata are small openings on the underside of leaves for gas exchange (O2 & CO2)

Plants also lose H2O through stoma so they are closed during the hottest part of the day Alternate Pathwa