Bio Quiz-Photosynthesis

Front 1

Equation for Photosynthesis

Back 1

12H20 + 6CO2 + Sunlight -> 602 + C6H1206 + 6H2O
water + carbon dioxide + energy yields sugar + water + oxygen

Front 2

What is the cite of photosynthesis?

Back 2

Chloroplasts. (any green part of a plant, leaves primary location) Green color from chlorophyll, which absorbs the light energy that drives photosynthesis

Front 3

Structure/Function of Chloroplast

Back 3

Inside chloroplast
-light dependent occur along thylakoid membrane and hydrogen is pumped into the lumen
-light independant reactions happen in the stroma

Front 4

Radiation

Back 4

Dual Nature
photon-packet of energy
wave-amount of energy per unit
lower wavelengths have more energy (400)
higher wavelengths have less energy (700)

Front 5

Radiation Can Be

Back 5

Reflected, transmitted, absorbed. Pigments absorb photons at different wavelengths. Leaves are green because they reflect green radiation while absorbing red and blue radiation

Front 6

Pigments

Back 6

Photosynthetic pigments absorb radiation in order to drive photosynthesis. Primary pigment=chlorophyll
Carotenoid=accessory pigment
primary pigment in red algae and cyanobacteria are phycobilins

Front 7

Location and Structure of Chlorophyll

Back 7

Cluster of pigments embedded in thylakoid membrane
Porphyrin ring=light absorbing head of molecule
hydrocarbon tail

Front 8

Rate of Photosynthesis

Back 8

Chlorophyll absorbs red, violet, and blue radiation
carotenoids absorb violet and blue radiation
Photosynthetic rate greatest with red violet and blue radiation

Front 9

oxidation reduction pathway

Back 9

photosynthesis=redox reaction
water is split and electrons and H+ atoms are transferred from H20 to CO2, reducing it to sugar
Radiation boosts the energy of electrons so they can travel from water to sugar

Front 10

Two Photosynthesis Reactions-Light Dependent

Back 10

Light Dependent: Energy from the sun is absorbed and converted to ATP. Water is split into hydrogen and oxygen. The electron carrier NADP+ picks up two electrons and a H+ to make NADPH

Front 11

Products of Light Dependent Reactions

Back 11

ATP, NADPH, Oxygen gas

Front 12

Light INdependent

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ATP energy is used to synthesize G3P from carbon, oxygen, and hydrogen atoms. CO2 provides the carbon and oxygen. Water provides the electrons and hydrogen ions via NADPH. Product=sugar

Front 13

G3P

Back 13

glyceraldehyde 3-phosphate

Front 14

Light DEpendent Reactions- Absorption and Electrons

Back 14

Energy is absorbed by photosynthetic pigments and transferred to a special pair of chlorophylls in a protein called a photosystem. An electron in the special pair is excited to a higher energy level (Farther away from the nucleus) The electron is then passed along electron acceptors via redox reactions. As electrons release energy moving down the electron chain ladder, electrons are pumped from the stroma to the lumen

Front 15

Photosystems

Back 15

Photosystem II-reaction center with peak absorption at 680
Photosystem I-reaction center with peak absorption at 700
Difference due to protein environment of the chlorophyll a special pair, not the chlorophylls themselves
Work together to use radiative energy to generate ATP and NADPH

Front 16

PSII

Back 16

Absorbs a higher amount of energy (680) that energizes an e- in the special pair, located primarily on the granal stacks. e- passed along electron transport chain (redox reactions) to PSI and pumps H+ into the lumen of the stroma. PSII replaces lost electron with one from water

Front 17

Water Splitting Complex

Back 17

Located on the lumenal side of the thylakoid membrane. When water is split to provide PSII with e-, the resulting H+ enhance the hydrogen ion gradient from the lumen to the stroma

Front 18

PSI

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PSI absorbs lower amount of energy (700), re-energizes the electron from PSII. Located on stromal lamellae. This electron passed on second electron chain, to NADP+ to form NADPH (final electron acceptor)
(PSI replaces lost electron from PSII)

Front 19

Special Pair, Chlorophyll a

Back 19

Participates directly in light reactions. Accessory pigments absorb light and transfer energy to chlorophyll a.

Front 20

Light Reactions

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when PSII absorbs light, excited electron from special pair is captured by the primary electron receptor, leaving PSII oxidized. (enzyme pulls electrons off water to give back to PSII) causes water to split into 2 H+ ions and an O ion. O atom combines with another O atom to form O2.

Front 21

Electrons carry the energy of the sun

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as electrons pass down electron transport chain , energy converted into ATP. Eventually electrons end up at oxidized PSI reaction center

Front 22

Light Rxns cont.

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When PSI absorbs light, an excited electron from special pair captured by different primary electron acceptor, leaving PSI oxidized

Front 23

Electrons carry energy of the sun pt 2

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Electrons passed down second electron transport chain, and end up at oxidized NADP+. Electrons deposited onto NADP+ to create NADPH2, which carries electrons and protons (H+) to the calvin cycle

Front 24

Cyclic Electron Flow

Back 24

Under certain conditions excited electrons from PSI can travel an alternate pathway, cyclic electron flow. Cycle from rxn center to primary electron acceptor, along an electron transport chain, and returns to oxidized PSI (P700) chlorophyll. Non cyclic flow creates roughly equal ATP and NADPH. Calvin cycle consumes more ATP than NADPH. Cyclic E flow allows chloroplast to generate enough excess ATP to satisfy higher demand for ATP for Calvin Cycle

Front 25

ATP Formation

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ATP is made as H+ ions flow from lumen to stroma through protein called ATP Synthase. Analogous to a dam. Proton gradient across the thylakoid membrane is large and provides form of stored energy.

Front 26

ATP Synthase

Back 26

As electrons move down electron transport chain, they cause H+ to be pumped from the stroma into the lumen. As H+ diffuses through ATP synthase from the lumen to the stroma, stored energy in the proton gradient is converted into stored energy in ATP. ATP synthase primarily located on stromal lamallae

Front 27

Light INdependent Reactions

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"fixing" carbon reactions. Don't depend directly on the sun as long as ATP and NADPH are available. AKA the Calvin cycle

Front 28

Path of CO2

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CO2 in atmosphere diffuses into the leave through pores called stomata. Then diffuses across mesophyll (middle leaf) cell membrane and then across the chloroplast membrane into the stroma of the chloroplast

Front 29

3 Phases of the Calvin Cycle

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1-Carbon Fixation
2-Reduction
3-Regeneration

Front 30

Phase I: Carbon Fixation

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Each CO2 molecule is attached to the five carbon sugar ribulose bisphosphate (RuBP). This is catalyzed by RUBISCO. Resulting 6 carbon intermediate splits in half to form two molecules of 3-phosphoglycerate

Front 31

Phase II: Reduction

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Each 3-phosphoglycerate receives another Phosphate group from ATP to form 1,3 bisphosphoglycerate. A pair of electrons from NADPH reduces it to G3P

Front 32

Phase III: Regeneration

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Five G3P molecules rearranged to form 3 RuBP molecules. 3 ATP per one RuBP is spent to complete the cycle

Front 33

Overview of Calvin Cycle

Back 33

Each turn of the cycle fixes 1 carbon.
Regenerates starting material after molecules enter and leave the cycle
Carbon enters as CO2 and exits as a sugar
Spends ATP and uses reducing power of NADPH to make the sugar.
Actual sugar product=G3P

Front 34

C4 Photosynthesis-Initial Fixation

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Initial fixation of carbon is with enzyme PEPc. Greater affinity for CO2 than RUBISCO. Occurs in mesophyll cells. Resulting 4 carbon sugar then transported to adjacent bundle sheath cell. CO2 released and enters C3 cycle.

Front 35

Why some plants C4 photosynthesis

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Primary function; to pump CO2 into bundle sheath cells to create higher concentration CO2 inside sheath than in the air. RUBISCO can fix either CO2 or O2. If fixing O2=photorespiration (occurs on hot dry days)

Front 36

CAM photosynthesis

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INitial fixation of CO2 occurs at night by PEPc. Resulting 4 carbon sugar, malate, transported to vacuole until day time. Used because when stomata are open CO2 diffuses into leaf and H2O diffuses out, can be dangerous for plant in dry hot climate. (Cacti and succulents use CAM photosynthesis, because only opening stomata at night conserves water)