Photosynthesis · Objective: You will be able to contrast respiration and photosynthesis. Do Now: Take out your respiration lab Read p. 155 What type of organisms carry out photosynthesis

CAMPBELL BIOLOGY IN FOCUS

© 2014 Pearson Education, Inc.

Urry • Cain • Wasserman • Minorsky • Jackson • Reece

Lecture Presentations by

Kathleen Fitzpatrick and Nicole Tunbridge

8 Photosynthesis

Objective: You will be able to contrast respiration and photosynthesis.

Do Now:

Take out your respiration lab

Read p. 155

What type of organisms carry out photosynthesis

Photosynthesis converts light energy to the chemical energy of food


6 CO2 12 H2O Light energy C6H12O6 6 O2 6 H2O

6 CO2 6 H2O Light energy C6H12O6 6 O2


Figure 8.3 Leaf cross section

20 m

Mesophyll

Stomata

Chloroplasts Vein

CO2 O2

Mesophyll cell

Chloroplast

Stroma

Thylakoid

Thylakoid space

Outer membrane

Intermembrane space

Inner membrane

Granum

1 m


Figure 8.3b

20 m

Mesophyll cell

Chloroplast

Stroma

Thylakoid

Thylakoid space

Outer membrane

Intermembrane space

Inner membrane

Granum

1 m


Ohhh…The Splitting of Water...My Bad

• Chloroplasts split H2O into hydrogen and oxygen,

incorporating the electrons of hydrogen into sugar molecules

and releasing oxygen as a by-product



Figure 8.5

Light

CO2 H2O

P i

Chloroplast

Light

Reactions

Calvin

Cycle

[CH2O]

(sugar) O2

ADP

ATP

NADP

NADPH

The Two Stages of Photosynthesis: A Preview

Tell me one thins that this diagram is telling you.


Figure 8.5-1

Light

H2O

Chloroplast

Light

Reactions

P i

ADP

NADP


Figure 8.5-2

Light

H2O

P i

Chloroplast

Light

Reactions

O2

ADP

ATP

NADP

NADPH


Figure 8.5-3

Light

CO2 H2O

P i

Chloroplast

Light

Reactions

Calvin

Cycle

O2

ADP

ATP

NADP

NADPH


Figure 8.5-4

Light

CO2 H2O

P i

Chloroplast

Light

Reactions

Calvin

Cycle

[CH2O]

(sugar) O2

ADP

ATP

NADP

NADPH


Paired Work

• Work with a partner to list as many differences

between photosynthesis and cellular respiration as

you can.


Objective: You will be able to identify and justify the

most effective wavelengths for photosynthesis

Do Now:

– Read “Photosynthetic pigments” on p. 160

– Describe how a spectrophotometer works


Figure 8.7

Reflected light

Light

Absorbed light

Chloroplast

Granum

Transmitted light


Figure 8.8

Refracting prism

White light

Green light

Blue light

Chlorophyll solution

Photoelectric tube

Galvanometer

Slit moves to pass light of selected wavelength.

The low transmittance (high absorption) reading indicates that chlorophyll absorbs most blue light.

The high transmittance (low absorption) reading indicates that chlorophyll absorbs very little green light.

Technique

1

2

4

3


What would happen if we were to shine a red light?

What does that mean?


Figure 8.9a

Chloro- phyll a

Ab

so

rpti

on

of

lig

ht

by c

hlo

rop

las

t p

igm

en

ts Chlorophyll b

Carotenoids

(a) Absorption spectra

400 700 600 500

Wavelength of light (nm)


Figure 8.9b

(b) Action spectrum

400 700 600 500

Rate

of

ph

oto

syn

thesis

(m

easu

red

by O

2

rele

ase)


Individual Work

• Take a moment to look at all the diagrams from

figure 8.9 on p. 161

• Read through Engelmann’s experiment

• Answer “Which wavelengths of light are most

effective in driving photosynthesis?”

• State a claim (What you believe is the answer)

• Provide evidence from the reading to support your

claim

• Explain your reasoning (Why does your evidence

support your claim?)

– Use the word “Because or therefore in your explanation”


Figure 8.9c

Filament of alga

Aerobic bacteria

(c) Engelmann’s experiment

400 700 600 500


Figure 8.5-4

Light

CO2 H2O

P i

Chloroplast

Light

Reactions

Calvin

Cycle

[CH2O]

(sugar) O2

ADP

ATP

NADP

NADPH


Figure 8.11

Photon (fluorescence)

Ground state

(b) Fluorescence

Excited state

Chlorophyll molecule

Photon

Heat

e−

(a) Excitation of isolated chlorophyll molecule

En

erg

y o

f ele

ctr

on


Objective: You will be able to explain how the light

reactions generate ATP and NADPH.

• Do Now: • View the two stages of photosynthesis by looking at the

diagram on p. 159.

• List the reactants and products for each stage


The light reactions convert solar energy to the chemical

energy of ATP and NADPH


The light reactions (in the thylakoids)

Split H2O

Release O2

Reduce the electron acceptor, NADP, to NADPH

Generate ATP from ADP by adding a phosphate

group, photophosphorylation

Take one minute and draw a chloroplast in your notebook

Include:

Double membrane

Thylakoids

Grana

Stroma

Place an X where you would find chlorophyll

Leave a space to draw a different diagram of the

same size later

Figure 8.11

Photon (fluorescence)

Ground state

(b) Fluorescence

Excited state

Chlorophyll molecule

Photon

Heat

e−

(a) Excitation of isolated chlorophyll molecule

En

erg

y o

f ele

ctr

on


Figure 8.12a

(a) How a photosystem harvests light

STROMA

THYLAKOID SPACE (INTERIOR OF THYLAKOID)

Photosystem Photon

Light- harvesting complexes

Reaction- center complex

Primary electron acceptor

Special pair of chlorophyll a molecules

Transfer of energy

Pigment molecules

Th

yla

ko

id m

em

bra

ne

e−


Figure 8.13-5

Primary acceptor

2 H

O2

ATP

NADPH

Photosystem II (PS II)

H2O e−

e−

e−

Light

2 1

P680

Pq

Electron transport chain

Cytochrome complex

Pc

Pigment molecules

Primary acceptor

Photosystem I (PS I)

e−

P700

e− e−

Fd

Light

Electron transport chain

H

NADP

NADP

reductase

1

2

3

4

5

6

7

8

Energ

y


Figure 8.14

Photosystem II Photosystem I

NADPH

Mill makes

ATP


Paired Work

• Explain how each component of this

diagram relates to what we just learned.


Take one minute and draw a mitochondria next

to the chloroplast you drew

• Include: • Double membrane

• Intermembrane space

• Matrix

– Place an X where you would find ETC


Figure 8.16


To Calvin Cycle

H

THYLAKOID SPACE (high H concentration)

Thylakoid membrane

STROMA (low H concentration)

ATP synthase

NADPH

e−

Light NADP

ATP ADP

NADP

reductase

Fd H

Pq

Pc

Cytochrome complex

4 H

Light

2 H

O2

H2O

2 1

4 H

e−

1

2

3

P i


Objective: You will be able to explain how the

Calvin cycle builds carbohydrates.

• Do Now:

• Take out the photosynthesis packet

• Begin completing question #1

• Write in ETC, proton pumps and ATP

synthase


Figure 8.UN02

Calvin Cycle

NADPH

NADP

ATP

ADP

Light

CO2

[CH2O] (sugar)

Light Reactions

O2

H2O


• In cyclic electron flow

– Only photosystem I is used

– Only ATP is produced

Primary

acceptor

Pq

Fd

Cytochrome

complex

Pc

Primary

acceptor

Fd

NADP+

reductase

NADPH

ATP Figure 10.15


NADP+

The Calvin cycle uses the chemical energy of ATP and NADPH to reduce CO2 to sugar



Figure 8.17-3

6 P i

NADPH

Input 3

ATP

Calvin Cycle

as 3 CO2

Rubisco Phase 1: Carbon fixation

Phase 2: Reduction

Phase 3: Regeneration of RuBP

G3P Output

Glucose and other organic compounds

G3P

RuBP 3-Phosphoglycerate

1,3-Bisphosphoglycerate

6 ADP

6

6

6

6 P

3

P P

P

6 NADP

6 P

5 P

G3P

ATP

3 ADP

3

3 P P

1 P

P


Questions?

• What is the function of the Calvin cycle?

• List the reactants of the Calvin Cycle. The

products.

• How are the Calvin cycle and the Krebs cycle

similar? Different?

• Which cycle is your favorite?


Paired Work

Take 3-5 minutes and add

any additional information

you can that compares

aerobic cellular respiration

and photosynthesis.


Objective: You will be able to compare and contrast

C3, C4 and CAM plants.

• Do Now:

• Read “ Evolution of Alternative…” on p. 169

• Explain what is meant by the photosynthesis-water loss

compromise


Figure 8.17-3

6 P i

NADPH

Input 3

ATP

Calvin Cycle

as 3 CO2

Rubisco Phase 1: Carbon fixation

Phase 2: Reduction

Phase 3: Regeneration of RuBP

G3P Output

Glucose and other organic compounds

G3P

RuBP 3-Phosphoglycerate

1,3-Bisphosphoglycerate

6 ADP

6

6

6

6 P

3

P P

P

6 NADP

6 P

5 P

G3P

ATP

3 ADP

3

3 P P

1 P

P


Mesophyll

Leaf cross section

Chloroplasts Vein

Stomata

Chloroplast Mesophyll

cell

CO2 O2

20 m

Figure 10.4a


Figure 8.18

Bundle- sheath cell

Sugarcane

CO2

Pineapple

CO2

(a) Spatial separation of steps

C4

CO2 CO2

CAM

Day

Night

Sugar

Calvin Cycle

Calvin Cycle

Sugar

Organic acid

Organic acid

Mesophyll cell

(b) Temporal separation of steps

1

2

1

2



Figure 10.20b The C4 pathway

Mesophyll cell PEP carboxylase

CO2

Oxaloacetate (4C) PEP (3C)

Malate (4C)

Pyruvate (3C)

CO2

Bundle- sheath cell

Calvin Cycle

Sugar

Vascular tissue

ADP

ATP


• In most plants (C3 plants), initial fixation of CO2,

via rubisco, forms a three-carbon compound

• In photorespiration, rubisco adds O2 instead of

CO2 in the Calvin cycle

• Photorespiration decreases photosynthetic output by

consuming ATP, organic fuel and releasing CO2 without

producing sugar


The Photorespiration “Mistake”


Objective: You will be able to compare and contrast

C3, C4 and CAM plants.

Reminder


Paired Work

• Complete the Scientific Skills Exercise on p. 170

• Please be aware that in question “3b” you need to:

• State a claim

• Provided evidence

• Explain your reasoning (because, therefore)

• Make 1 critique about the experiment


Figure 8.UN04


Distance of

solvent front

from origin

Distance of

pigment from

origin

RF = distance of pigment from origin

distance of solvent front from origin


Figure 8.19

Photosystem II Electron transport chain

Calvin Cycle

NADPH

Light

NADP

ATP

CO2 H2O

ADP

3-Phosphpglycerate

G3P

RuBP

Sucrose (export)

Starch (storage)

Chloroplast

O2

Light Reactions:

Photosystem I Electron transport chain

P i


Figure 8.UN07

pH 7

pH 4 pH 8

pH 4

Documents

Photosynthesis · Objective: You will be able to contrast respiration and photosynthesis. Do Now: Take out your respiration lab Read p. 155 What type of organisms carry out photosynthesis