Photosynthesis Photosynthesis and Cellular and Cellular RespirationRespiration

Energy for LifeEnergy for Life

Complementary Complementary processesprocesses

Photosynthesis is Photosynthesis is an important part an important part of the carbon cycle.of the carbon cycle.

The processes of The processes of photosynthesis and photosynthesis and cellular respiration cellular respiration are complementary are complementary processes, processes, meaning they work meaning they work together to benefit together to benefit living organisms.living organisms.

Plants and animals Plants and animals contribute…contribute…

Autotrophs, such as plants, produce Autotrophs, such as plants, produce glucose using the carbon in carbon dioxide.glucose using the carbon in carbon dioxide.

Both autotrophs and heterotrophs, such as Both autotrophs and heterotrophs, such as grasshoppers that eat plants, use those grasshoppers that eat plants, use those carbohydrates in cellular respiration. carbohydrates in cellular respiration.

Respiration, in turn, produces carbon Respiration, in turn, produces carbon dioxide.dioxide.

Photosynthesis equationPhotosynthesis equation

lightlight

6 CO6 CO22 + 6 H + 6 H22O O CC66HH1212OO66 + 6O + 6O22

Photosynthesis combines water, Photosynthesis combines water,

carbon dioxide and sunlight to carbon dioxide and sunlight to produce glucose and oxygen, produce glucose and oxygen, converting light energy into converting light energy into chemical energy.chemical energy.

Respiration equationRespiration equation

6O6O22 + C + C66HH1212OO66 6CO 6CO22 + H + H22O + O + EnergyEnergy

Respiration breaks down glucose Respiration breaks down glucose and other food molecules in the and other food molecules in the presence of oxygen.presence of oxygen.

Energy renewalEnergy renewal Energy captured Energy captured

from sunlight by from sunlight by photosynthetic photosynthetic organisms is used organisms is used and released in the and released in the cellular respiration cellular respiration of living things.of living things.

The energy that The energy that living things use, living things use, must continually be must continually be renewed through renewed through photosynthesis.photosynthesis.

Where does photosynthesis Where does photosynthesis occur?occur?

In plants and other In plants and other photosynthetic photosynthetic eukaryotes, eukaryotes, photosynthesis takes photosynthesis takes place inside place inside chloroplasts. chloroplasts.

The chloroplasts The chloroplasts contain saclike contain saclike membranes called membranes called thylakoids.thylakoids.

Thylakoids are Thylakoids are arranged in stacks arranged in stacks known as grana.known as grana.

PhotosystemsPhotosystems

Proteins in the Proteins in the thylakoid organize thylakoid organize chlorophyll and chlorophyll and other pigments other pigments into light-into light-collecting units collecting units called called photosystems.photosystems.

What are the reactions of What are the reactions of photosynthesis?photosynthesis?

Scientists divide the reactions of Scientists divide the reactions of photosystems into two parts: Light-photosystems into two parts: Light-dependent reactions and light-dependent reactions and light-independent reactions or the Calvin cycle.independent reactions or the Calvin cycle.

TheThe light-dependent reactions light-dependent reactions take take place within the thylakoid membranes.place within the thylakoid membranes.

They use energy from light to produce They use energy from light to produce ATP and NADPH, which are energy ATP and NADPH, which are energy carriers.carriers.

Light-dependent Light-dependent reactionsreactions

Photosystem II absorbs light and breaks Photosystem II absorbs light and breaks water molecules into energized electrons, water molecules into energized electrons, hydrogen ions (H+) and oxygen.hydrogen ions (H+) and oxygen.

High-energy electrons move through the High-energy electrons move through the electron transport chain from photosystem II electron transport chain from photosystem II to photosystem I.to photosystem I.

As electrons pass from chlorophyll to As electrons pass from chlorophyll to NADP+, more hydrogen ions are pumped NADP+, more hydrogen ions are pumped across the membrane.across the membrane.

ATP synthase in the membrane allows H+ ATP synthase in the membrane allows H+ ions to pass through it. The enzyme binds ions to pass through it. The enzyme binds ADP and a phosphate group to produce ATP. ADP and a phosphate group to produce ATP.

Light-dependent Light-dependent reactionsreactions

Light-dependent Light-dependent reactionsreactions

Light-independent Light-independent reactionsreactions

TheThe light-independent reactionslight-independent reactions of the Calvin Cycle take place in the of the Calvin Cycle take place in the stroma outside of the thylakoid stroma outside of the thylakoid membranes.membranes.

The Calvin Cycle uses ATP and The Calvin Cycle uses ATP and NADPH from the light-dependent NADPH from the light-dependent reactions to produce high-energy reactions to produce high-energy sugars.sugars.

Light-independent Light-independent reactionsreactions

What is the visible What is the visible spectrum of light and why spectrum of light and why

is it important?is it important?

The visible spectrum of light is the set The visible spectrum of light is the set of varying wavelengths of light that of varying wavelengths of light that are visible to our eyes as different are visible to our eyes as different colors. colors.

Sunlight is a mixture of different Sunlight is a mixture of different wavelengths of light, even though it wavelengths of light, even though it appears as “white light” to your eyes.appears as “white light” to your eyes.

The visible spectrumThe visible spectrum

Pigments absorb lightPigments absorb light In addition to water and In addition to water and

carbon dioxide, carbon dioxide, photosynthesis requires light photosynthesis requires light and chlorophyll, a pigment and chlorophyll, a pigment molecule within chloroplasts.molecule within chloroplasts.

The two main types are The two main types are chlorophyll a and chlorophyll chlorophyll a and chlorophyll b.b.

Chlorophyll absorbs blue-Chlorophyll absorbs blue-violet and red light very well. violet and red light very well. Green light is reflected by Green light is reflected by plant leaves, which is what plant leaves, which is what gives them their green color.gives them their green color.

Light absorption powers Light absorption powers photosynthesisphotosynthesis

Chlorophyll absorbs Chlorophyll absorbs blue-violet and red light blue-violet and red light very well. Green light is very well. Green light is reflected by plant reflected by plant leaves, which is what leaves, which is what gives them their green gives them their green color.color.

The high-energy The high-energy electrons produced electrons produced when chlorophyll when chlorophyll absorbs light make absorbs light make photosynthesis work.photosynthesis work.

Photosynthesis Photosynthesis ReviewReview

Photosynthesis Photosynthesis ReviewReview

Photosynthesis Photosynthesis ReviewReview

Cellular RespirationCellular Respiration

Living things need Living things need energy…energy…

Our bodies have a Our bodies have a lot of work to do lot of work to do every day…every day… Moving muscles,Moving muscles, Building essential Building essential

molecules, and molecules, and Transporting Transporting

substances across substances across cell membranes.cell membranes.

Where do we get energy?Where do we get energy?

Food provides the Food provides the energy living energy living things need to things need to grow and grow and reproduce.reproduce.

Food is the source Food is the source of the material of the material our cells use to our cells use to build new build new molecules.molecules.

How much energy is How much energy is present in food?present in food?

Quite a lot!Quite a lot!

One gram of the sugar One gram of the sugar glucose (Cglucose (C66HH1212OO66) when ) when burned in the presence burned in the presence of oxygen, releases of oxygen, releases 3,811 calories of heat 3,811 calories of heat energy. energy.

A calorie is the amount A calorie is the amount of energy needed to of energy needed to raise the temperature raise the temperature of 1 gram of water 1 of 1 gram of water 1 degree Celsius.degree Celsius.

What is cellular What is cellular respiration?respiration?

Cellular respiration is the Cellular respiration is the process that releases energy by process that releases energy by breaking down glucose and breaking down glucose and other food molecules in the other food molecules in the presence of oxygen.presence of oxygen.

6O2 + C6H12O6 6CO2 + 6H2O + Energy

oxygen + glucose carbon dioxide + water + energy

Where does cellular Where does cellular respirationrespiration take place? take place?

The beginning pathway The beginning pathway of cellular respiration, of cellular respiration, glycolysisglycolysis, takes place , takes place in the cell cytoplasm.in the cell cytoplasm.

The two remaining The two remaining pathways—the pathways—the Krebs Krebs CycleCycle and and electronelectron transporttransport—take place —take place inside the mitochondria inside the mitochondria of the cell. of the cell.

Cellular Respiration Cellular Respiration OverviewOverview

Glycolysis:Glycolysis: a glucose a glucose molecule is split to produce molecule is split to produce two molecules of pyruvic two molecules of pyruvic acid.acid.

Krebs Cycle:Krebs Cycle: pyruvic acid is pyruvic acid is used to produce carbon used to produce carbon dioxide, NADH, ATP and dioxide, NADH, ATP and FADHFADH22. Sometimes called . Sometimes called the citric acid cycle because the citric acid cycle because citric acid is first formed.citric acid is first formed.

Electron Transport Chain:Electron Transport Chain: uses high-energy electrons uses high-energy electrons from the Krebs Cycle to from the Krebs Cycle to convert ADP to ATP.convert ADP to ATP.

GlycolysisGlycolysis

Kreb CycleKreb Cycle

ATP

NETS: 3NADH, 1ATP, 1FADHNETS: 3NADH, 1ATP, 1FADH22, & 2CO, & 2CO22

Kreb CycleKreb Cycle

What happens if oxygen What happens if oxygen is not available?is not available?

GlycolysisGlycolysis is then is then followed by a different followed by a different pathway.pathway.

The combined process The combined process of this pathway and of this pathway and glycolysis is called glycolysis is called fermentation.fermentation.

FermentationFermentation releases releases energy from food energy from food molecules by producing molecules by producing ATP in the absence of ATP in the absence of oxygen.oxygen.

FermentationFermentation

Cellular Respiration Cellular Respiration SummarySummary