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Ecosystem RecyclingEcosystem Recycling

Chapter 9

Section 9.2 and 9.3

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The Carbon CycleThe Carbon CycleCarbon is cycled through ecosystems mainly through the

processes of photosynthesis and cell respiration.

PhotosynthesisPhotosynthesis – converting – converting light energy light energy into into chemical energy chemical energy stored in stored in organic compounds (carbohydrates)organic compounds (carbohydrates)Formula: 6 CO2 + 6 H2O + sun C6H12O6 + 6 O2

(energy) (glucose)*Autotrophs (producers) carry out photosynthesis to make food

Cellular RespirationCellular Respiration-- process of cells process of cells making energymaking energy (ATP) by breaking (ATP) by breaking down organic compoundsdown organic compoundsFormula: C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP

(Glucose) (energy) *Heterotrophs (consumers) AND autotrophs (producers) use cell respiration

to get energy from food

What do you notice about the equations for these two processes???**** The products of one are the reactants for the other

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Photosynthesis to RespirationPhotosynthesis to Respiration Heterotrophs Heterotrophs eat other organismseat other organisms, and autotrophs use the , and autotrophs use the

process of process of photosynthesis to create their own food.photosynthesis to create their own food.

Once heterotrophs eat food, or autotrophs make food, Once heterotrophs eat food, or autotrophs make food, cellular cellular respiration takes place to break down food molecules and respiration takes place to break down food molecules and release energy in the form of ATP.release energy in the form of ATP. ATP (adenosine triphosphate) – chemical compound ATP (adenosine triphosphate) – chemical compound used by cells to used by cells to

store and release energystore and release energy

Cellular respiration provides the ATP that all cells need to Cellular respiration provides the ATP that all cells need to support the activities of life.support the activities of life.

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Photosynthesis takes place in the chloroplast

The Structure of the Chloroplast:

Double outer membrane

Thylakoids- inner

membranes arranged as

flattened sacs

Grana- stacks of thylakoids

Stroma- liquid solution

surrounding grana

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Overview of Photosynthesis

• “Photo” = light “Synthesis” = to make

• Photosynthesis is a process which makes organic compounds (sugars) using sunlight

– Converts solar energy into chemical energy (energy stored in bonds of chemical compounds)

• There are 2 main steps to photosynthesis:1. Light-Dependent (Light) Reactions 2. Light-Independent (Dark) Reactions

Animation

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Light Reactions• Converts solar energy into energy used for the

dark reactions.• Requires the absorption of sunlight and water.

– Pigments like chlorophyll aid in the absorption of sunlight.

• Takes place in the thylakoid membranes of the chloroplast.

• Products include ATP and a molecule called NADPH.– Serve as an energy source for the next step of the process.

• Oxygen is also produced as a by-product.– Much of the oxygen is given off to the atmosphere.

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Light Independent Reactions (calvin cycle)

• Takes carbon from CO2 and puts it into organic compounds (process called carbon fixation).

• Requires CO2 from the atmosphere and ATP and NADPH as energy sources.– ATP and NADPH are produced during the light reactions.

• Takes place in the stroma of the chloroplast.

• Produces glucose and other organic compounds.– Broken down and used for energy.– Stored for future energy needs.

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Factors Affecting Photosynthesis• Amount of water

– Shortage of water can slow or even stop photosynthesis

– Plants in dry climates have waxy coating on leaves to prevent water loss.

• Temperature

– Enzymes of photosynthesis function best around 35°C.

– Temperatures above and below this range can slow photosynthesis.

• Intensity of Light– Increase in light intensity increases rate of photosynthesis.

– At some point, plant reaches its maximum rate and cannot go any faster, no matter how much light is added.

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Cellular Respiration CC66HH1212OO66 + 6 O + 6 O22 6 CO6 CO2 2 + 6 H+ 6 H22O + energyO + energy

(Glucose)(Glucose) (ATP) (ATP)

• Cell respiration is a process which breaks down organic compounds to release energy in the form of ATP.

• Both heterotrophs AND autotrophs perform cell respiration.

• 2 kinds of cell respiration:– Anaerobic (takes place in absence of oxygen)– Aerobic (takes place in the presence of oxygen)

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Anaerobic Respiration• Does NOT use oxygen and takes place in the

cytosol.

• NOT efficient - produces only small amounts of ATP.– Used by prokaryotes or simple eukaryotes– Used by complex eukaryotes only as a backup to aerobic

respiration.

• 2 different kinds of anaerobic respiration:– Lactic Acid Fermentation– Alcoholic Fermentation

• Both produce by-products that are used by humans.

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Anaerobic Respiration (cont ‘d.) Lactic Acid Fermentation

Performed by bacteria. Produces lactic acid as a by-product. Lactic acid makes yogurt and cheese Lactic acid is made in your muscles during strenuous exercise and

can cause soreness and cramps.

Alcoholic Fermentation Performed by yeast. Produces ethyl alcohol and CO2 as by-products. Bread – CO2 bubbles push the dough up and make it rise. Makes wine and beer - Yeast breaks down the sugars in grains or

grapes producing CO2 and alcohol. Used to be used to make other carbonated beverages like root beer.

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Aerobic Respiration takes place in the mitochondria of BOTH plants & animals

picture • Double membrane (just like chloroplast)– Matrix – inner space– Cristae – folded inner

membranes

Why would you expect to have an abundance of mitochondria in your muscle cells?

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Aerobic Respiration• Occurs in the presence of oxygen and takes place in the

mitochondria.

• Much more efficient process than anaerobic respiration.– Produces about 19 times more ATP than anaerobic respiration.– Used by complex eukaryotes with large energy requirements.– Carbon dioxide and water created as by-products.

• 2 main parts to aerobic respiration:– Krebs Cycle – happens in matrix of mitochondria

• Takes the sugar and starts to break it down for the ETC

– Electron Transport Chain (ETC) – happens in cristae of mitochondria

• Where most ATP is produced

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Let’s wrap it up...Let’s wrap it up...

PhotosynthesisPhotosynthesis converts converts solar energy into solar energy into chemical energy (autotrophs).chemical energy (autotrophs).

RespirationRespiration makes makes ATP by breaking down ATP by breaking down organic compounds (either consumed or organic compounds (either consumed or made depending on whether organism is made depending on whether organism is an autotroph or heterotroph).an autotroph or heterotroph).

Products of photosynthesis are the reactants Products of photosynthesis are the reactants of cell respiration and vice versa.of cell respiration and vice versa.

Do all organisms carry out photosynthesis?Do all organisms carry out photosynthesis?

Do all organisms carry out some sort of Do all organisms carry out some sort of cellular respiration?cellular respiration?