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L06: Photosynthesis & Respiration

BIOL 153/LBlack Hills State Univ.Ramseys

I. Overview of photosynthesis

A. Chemical formula

CO2 + H2O + Energy => C6H12O6 + O2

input output

B. Chloroplast

See lecture'Chloroplast Origins'

1. Pigments

chlorophyll + carotenoids

2. Membranes

inner/outer + thylakoid membranes

3. Electrons

photosystem ETS

4. Chemical bonds

carbohydrates assembled

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C. Action spectrum 1. Types of electromagnetic radiation

1. Types of electromagnetic radiation 2. Wavelengths used by plants

blue light: ~400 - 500 nm

red light: ~600 - 700 nm

2. Wavelengths used by plants

why are plants green?

D. Biochemical pathways

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1. Light reactions

light energy converted to ATP + NADPH

2. Dark Reactions

ATP + NADPH assembles carbohydrates

II. Overview of respiration

A. Chemical formula

C6H12O6 + O2 => CO2 + H2O + Energy

input output

B. Mitochondria

See lecture'Origin of Chloroplasts'

1. Membranes

inner/outer membranes (cristae)

2. Electrons

respiration ETS

3. Chemical bonds

Carbohydrates disassembled

See lecture'Origin of Chloroplasts'

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C. Biochemical pathways 1. Aerobic (high ATP yield)

Glycolysis => Respiration(cytosol) (mitochondria)

2. Anaerobic (low ATP yield)

Glycolysis => Fermentation(cytosol) (cytosol)

III. P&R as opposing biochem forces

ouput of photosynthesis = input for respiration(and vice versa)

Fig. 6-5Raven p. 95

IV. Measurement of P&R

super insightful!

organic molecules made (P)

minus

organic molecules burned (R)

• Option #1: Biomass

terrestrial:straightforward

aquatic:straightforward

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• Option #2: Gas exchange

O2 produced (P)

or

CO2 produced (R)

terrestrial:challenging

aquatic:straightforward

leaf disk

water column

Leaf disk assay

Scenario #1: P > R

• more O2 made vs. consumed

• O2 accumulates in leaf

• bouyant bubbles

• leaf floats

Scenario #2: R > P

• more O2 consumed vs. made

• O2 disappears in leaf

• no bouyount bubbles

• leaf drops

V. Terrestrial consequences of P&R

photosynthetic organisms transformed earth(geological time)

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VI. Aquatic consequences of P&R

photosynthetic organisms transform water bodies(daily + seasonally)

Waves (lake surface)

A. Sources of oxygen

• Atmosphere

• Small photosynthetic plankton: P

• Large photosynthetic plants: P

B. Sources of carbon dioxide

• Decomposition

• Heterotrophic organisms: R

• Photosynthetic organisms: R

C. Changes through day

Summer (Day) Summer (Night)

Wind

Waves (lake surface)

Phyto-plankton

Wind

Waves (lake surface)

Summer (Day) Summer (Night)

Wind

Waves (lake surface)

Phyto-plankton

High O2

Wind

Waves (lake surface)

High CO2

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D. Changes through seasons

Summer (Day) Winter (Day)

Wind

Waves (lake surface) Ice

Snow

Phyto-plankton

Summer (Day) Winter (Day)

Wind

Waves (lake surface) Ice

Snow

Phyto-plankton

High O2

Low O2 Min O2