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Energy Conversions Photosynthesis Cellular Respiration

Energy Conversions Photosynthesis Cellular Respiration

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Page 1: Energy Conversions Photosynthesis Cellular Respiration

Energy Conversions

PhotosynthesisCellular Respiration

Page 2: Energy Conversions Photosynthesis Cellular Respiration
Page 3: Energy Conversions Photosynthesis Cellular Respiration

Energy Conversion

• Energy: The ability to do work or cause motion– Potential E: “Stored Energy”; Energy of

position– Kinetic Energy: Energy of motion– Chemical Energy: Potential Kinetic

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Exothermic Vs Endothermic

• Exothermic: Gives off heat– Examples: Fire

• Endothermic: Absorbs heat– Examples: Cold Pack, Photosynthesis

Page 8: Energy Conversions Photosynthesis Cellular Respiration

Fig. 10-2

(a) Plants

(c) Unicellular protist10 µm

1.5 µm

40 µm(d) Cyanobacteria

(e) Purple sulfur bacteria

(b) Multicellular alga

• Photosynthesis:– in plants– algae, – Some protists– some prokaryotes

BioFlix: PhotosynthesisBioFlix: Photosynthesis

Page 9: Energy Conversions Photosynthesis Cellular Respiration

Structures of Photosynthesis

• Chloroplasts are structurally similar to photosynthetic bacteria

• Leaves are the main area of Photosynthesis

• Their green color is from chlorophyll, the green pigment

• CO2 enters and O2 exits the leaf through pores called stomata

Page 10: Energy Conversions Photosynthesis Cellular Respiration

Fig. 10-3a

5 µm

Mesophyll cell

StomataCO2 O2

Chloroplast

Mesophyll

VeinLeaf cross section

• Chloroplasts are found in cells of the mesophyll, the interior tissue of the leaf– A typical

mesophyll cell has 30–40 chloroplasts

• Thylakoid• Grana• Stroma

Page 11: Energy Conversions Photosynthesis Cellular Respiration

Component of a Chloroplast• Thylakoid –

– Saclike photosynthetic membranes

– Light-dependent reactions occur here

• Granum / Grana:– – Stack of thylakoids

• Stroma – – Region outside the

thylakoid membrane– Reactions of the Calvin

Cycle occur here

Page 12: Energy Conversions Photosynthesis Cellular Respiration

The Photosynthesis Equation6 CO2 + 6 H2O (light energy) C6H12O6 + 6 O2 (water given off also)

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• Light-dependent reactions– Occurs in

Thylakoid

– Used H2O and light to produce ATP, NADPH, and O2

– NADPH is an electron carrier

• Calvin cycle– Occurs in stroma– uses carbon dioxide, ATP, and

NADPH to produce sugars

Page 14: Energy Conversions Photosynthesis Cellular Respiration

Photosynthesis Goal? – What is it?

• Needs Energy: – Photophosphorylation – – The production of ATP using energy from an

electron transport chain.

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Photosynthesis

• The light reactions:– (in the thylakoids):

– Split H2O

– Release O2

– Reduce NADP+ to NADPH

– Generate ATP from ADP by photophosphorylation

• The Calvin cycle – (in the stroma) forms

sugar from CO2, using ATP and NADPH

– The Calvin cycle begins with carbon fixation, CO2 into organic molecules

• Photosynthesis: – Light reactions (the photo part)– Calvin cycle (the synthesis part)

Page 16: Energy Conversions Photosynthesis Cellular Respiration

Light

Fig. 10-5-1

H2O

Chloroplast

LightReactions

NADP+

P

ADP

i+

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Light

Fig. 10-5-2

H2O

Chloroplast

LightReactions

NADP+

P

ADP

i+

ATP

NADPH

O2

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Light

Fig. 10-5-3

H2O

Chloroplast

LightReactions

NADP+

P

ADP

i+

ATP

NADPH

O2

CalvinCycle

CO2

Page 19: Energy Conversions Photosynthesis Cellular Respiration

Light

Fig. 10-5-4

H2O

Chloroplast

LightReactions

NADP+

P

ADP

i+

ATP

NADPH

O2

CalvinCycle

CO2

[CH2O]

(sugar)

Page 20: Energy Conversions Photosynthesis Cellular Respiration

The light reactions convert solar energy to the chemical energy of ATP and NADPH

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 10-7

Reflectedlight

Absorbedlight

Light

Chloroplast

Transmittedlight

Granum

• Chloroplasts are solar-powered chemical factories– Their thylakoids

transform light energy into chemical energy:

• ATP • NADPH

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jj jj jj jj

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Sunlight

• Light is a form of electromagnetic energy• The electromagnetic spectrum is the entire

range of electromagnetic energy, or radiation • Visible light consists of wavelengths (including those

that drive photosynthesis) that produce colors we can see

Wavelength is the distance between crests of waves•Wavelength determines the type of electromagnetic energy

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UV

Fig. 10-6

Visible light

InfraredMicro-waves

RadiowavesX-raysGamma

rays

103 m1 m

(109 nm)106 nm103 nm1 nm10–3 nm10–5 nm

380 450 500 550 600 650 700 750 nm

Longer wavelength

Lower energyHigher energy

Shorter wavelength

Page 31: Energy Conversions Photosynthesis Cellular Respiration

Light and Pigments

• Pigments – light absorbing chemicals

• Chlorophyll – Chlorophyll a– Chlorophyll b– Carotenoids– Xanthophyll

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Why do leaves change colors?

• Chlorophyll a

• Chlorophyll b

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Page 34: Energy Conversions Photosynthesis Cellular Respiration

NADP+ + e- + Energy NADPH

• NADP+ – (Nicotinamide adenine

dinucleotide phosphate)

– Electron, hydrogen, and energy carrier

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Light-Dependant

Reactions

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1. Photosystem II

• Chlorophyll absorbs light

• Electrons on a chlorophyll molecule (p680) absorb energy (become excited) are “energized”

• High-energy electrons are passed on to the electron transport chain

• Chlorophyll’s electrons are replenished by the breakdown of H2O

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2. Electron Transport Chain

• The molecules of the electron transports chain use high-energy electrons to push H+ ions from the stroma into the inner thylakoid space.

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3. Photosystem I

• Chlorophyll absorbs light-energy and re-energized the electrons from photosystem II.

• NADP+ picks up these high-energy electrons and H+ to become NADPH.

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Page 40: Energy Conversions Photosynthesis Cellular Respiration

4. Hydrogen Ions

• Chemiosmosis = Electrochemical Gradient

• Hydrogen ions build up inside the thylakoid membrane.– High concentration of H+ inside the

membrane (Strong Positive Charge)– Low concentration of H+ outside the

membrane (Negative Charge)– Provides the energy to form ATP

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5. ATP formation

• H+ try to reach equilibrium.

• Pass through the ATP synthase

• Movement of H+ ions through the ATP synthase powers ATP production

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Calvin

Cycle

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The Calvin Cycle / Dark Reaction

1. 6 CO2 molecules enter the cycle.

2. Enzyme “rubisco” (RuBP) forms 3-carbon molecules

3. ATP and NADPH form the High energy 3-Carbon molecules (G3P)

4. 2 (G3P)are combined to form a 6-carbon sugar

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Calvin

Cycle

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Factors Affecting Photosynthesis

• Water supply

• Amount of sunlight

• Temperature

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LAB: Plant Pigments

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Types of Photosynthesis

• C3 Photosynthesis

• C4 Photosynthesis

• CAM Photosynthesis

Page 50: Energy Conversions Photosynthesis Cellular Respiration

C3 Plants (Most Plants)

• Called C3 because the CO2 is first incorporated into a 3-carbon compound.

• Stomata are open during the day.

• Photosynthesis takes place throughout the leaf.

• Adaptive Value: more efficient than C4 and CAM plants under cool and moist conditions and under normal light because requires less machinery (fewer enzymes and no specialized anatomy)

Page 51: Energy Conversions Photosynthesis Cellular Respiration

C4 plants

• Called C4 because the CO2 is first joined to make a 4C compound.

• Stomata are open during the day • Adaptive Value:

– Photosynthesizes faster than C3 plants – Can take HEAT and intense sunlight – Better water use enzymes brings in CO2 faster and so

does not need to keep stomata open as much (less water lost

by transpiration) for the same amount of photosynthesis. – Examples: four-wing saltbush, corn, and many of

our summer annual plants.

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CAM Plants:• CAM stands for Crassulacean Acid Metabolism

• Stomata open at night (when evaporation rates are usually lower)

• During the day, the acid is broken down and the CO2 is released to RUBISCO for photosynthesis

• Adaptive Value: – Better Water Use Efficiency than C3 plants under dry conditions due

to opening stomata at night when transpiration rates are lower (no

sunlight, lower temperatures, lower wind speeds, etc.).

• Examples: CAM plants include many succulents such as cactuses and agaves and also some orchids and bromeliads

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Page 54: Energy Conversions Photosynthesis Cellular Respiration

Cellular Respiration

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Cellular Respiration

• Transforming the “potential” energy in food into chemical energy cells can use: ATP

• CR = same way in plants and animals.

• Overall Reaction:– C6H12O6 + 6O2 → 6CO2 + 6H2O

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Cellular Respiration Overview

• Breakdown of glucose starts in the cytoplasm:

• At this point life diverges into two forms and two pathways– Anaerobic respiration = fermentation– Aerobic cellular respiration = High amounts of

ATP

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C.R. Reactions

• Glycolysis– Glucose molecule broken down into two 3-

carbon molecules called pyruvate– Process is ancient / all organisms from

simple bacteria to humans perform it the same way

– Yields 2 ATP molecules for every one glucose molecule broken down

– Yields 2 NADH per glucose molecule

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Page 59: Energy Conversions Photosynthesis Cellular Respiration

Anaerobic Cellular Respiration

• Some organisms thrive in environments with little or no oxygen– Marshes, bogs, gut of animals, sewage treatment ponds

• No oxygen used = anaerobic• Results in no extra ATP

– ONLY to regenerate NAD+ so it can return to pick up more electrons and hydrogens

• End products: Alcohol or Lactic Acid:

– YEAST & PLANTS: Ethanol and CO2 in beer/bread

– MUSCLE CELLS: Lactic Acid

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Aerobic Cellular Respiration

• Oxygen required = aerobic

• 2 more sets of reactions which occur in a specialized structure within the cell called the mitochondria– 1. Kreb’s Cycle– 2. Electron Transport Chain

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Kreb’s Cycle

• Completes the breakdown of glucose– Pyruvate 3-C broken down, the carbon and

oxygen atoms end up in CO2 and H2O

– Hydrogens and electrons are stripped and loaded onto NAD+ and FAD to produce NADH and FADH2

• Production of only 2 more ATP but loads up the coenzymes with H+ and electrons which move to the 3rd stage

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Page 64: Energy Conversions Photosynthesis Cellular Respiration

Electron Transport Chain

• Electron carriers loaded with electrons and protons from the Kreb’s cycle move to this chain-like a series of steps (staircase).

• As electrons drop down stairs, energy released to form a total of 32 ATP

• Oxygen waits at bottom of staircase, picks up electrons and protons and in doing so becomes water

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Page 68: Energy Conversions Photosynthesis Cellular Respiration

Energy Tally

• 36 ATP for aerobic – vs.

• 2 ATP for anaerobic

– Glycolysis 2 ATP– Kreb’s 2 ATP– Electron Transport 32 ATP

36 ATP• Anaerobic organisms can’t be too energetic but are important for

global recycling of carbon

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Cellular Respiration Song

• http://www.youtube.com/watch?v=3aZrkdzrd04

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Review – Compare / Contrast

• Photosynthesis & Cellular Respiration

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Comparing Photosynthesis & Respiration

Photosynthesis Cellular Respiration

Function Energy Storage Energy Release

Location Chloroplasts Mitochondria

Reactants CO2 and H2O C6H12O6 and O2

Products C6H12O6 and O2 CO2 and H2O

Equation 6CO2 + 6H2O C6H12O6 + 6O2

C6H12O6 + 6O2

6CO2 + 6H2O

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Redox Reactions• A chemical reaction involving the transfer of

one or more elections from one reactant to another; also called oxidation/reduction reactions

• In oxidation, a substance loses electrons, or is oxidized

• In reduction, a substance gains electrons, or is reduced (the amount of positive charge is reduced)

Page 82: Energy Conversions Photosynthesis Cellular Respiration

Fig. 9-UN1

becomes oxidized(loses electron)

becomes reduced(gains electron)

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Fig. 9-UN2

becomes oxidized

becomes reduced

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Reverse Process of Each Other

• Oxidative phosphorylation O2 reduced to H2O using electrons donated by NADH or FADH2 (Respiration)

• Photophosphorylation just the reverse, H2O oxidized to O2 with electrons accepted (Photosynthesis)

Page 85: Energy Conversions Photosynthesis Cellular Respiration

The Light-Dependent Reactions

• Photophosphorylation is the process of creating ATP using a Proton gradient created by the Energy gathered from sunlight.

• Chemiosmosis is the process of using Proton movement to join ADP and P.

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• What is the function of NADPH?

• How is light energy converted into chemical energy during photosynthesis?

• Can the complete process of photosynthesis take place in the dark? Explain your answer.