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Photosynthesis

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PHOTOSYNTHESIS

Photosynthesis •  Involves the Use Of Light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and Carbohydrates (sugars & starches)

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•  Goal of photosynthesis is creating glucose

•  Glucose is a monosaccharide

•  One Molecule of Glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP

•  Remember, C6H12O6 is not usable energy. It must be broken down during cellular respiration to be turned into ATP!

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The Photosynthesis Equation

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Pigments •  In addition to water, carbon dioxide, and light energy, photosynthesis requires pigments (molecules that absorb light).

• Chlorophyll is the primary light-absorbing pigment in autotrophs.

• Chlorophyll is found inside the chloroplasts in the thylakoid membrane

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Electromagnetic Spectrum •  Visible Light Contains A Mixture Of Wavelengths

•  Different Wavelengths Are Seen As Different Colors

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Inside A Chloroplast

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Why do plants appear green?

Structure of the Chloroplast •  Inner membrane—stacks of connected sacs called thylakoids

•  Thylakoid stack is called the granum (grana-plural)

•  Gel-like material around grana called stroma

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The Biochemical Reactions

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It Begins with Sunlight!

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Inside A Chloroplast

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Light Dependent Reactions

•  Occurs across the thylakoid membranes

•  Uses light energy •  Produce Oxygen from water •  Convert ADP to ATP •  Also convert NADP+ into the energy carrier NADPH

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LIGHT-DEPENDENT REACTIONS

SEE A MOVIE ATP SYNTHASE IN ACTION

Light Reaction Summary Reactants: (what goes in) •  H2O •  Light Energy Products: (what comes out) •  ATP •  NADPH •  Oxygen

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Light Dependent Reaction

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Calvin Cycle/ Light Independent Reactions

•  Light Independent reactions (AKA Calvin Cycle) occur in the stroma

• ATP used to make carbohydrates (sugars) like glucose (stored energy) and cellulose (strengthen the plant)

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CO2 Enters the Cycle

ATP and NADPH from light dependent reactions

5-Carbon Molecules Regenerated

Sugar produced

Calvin Cycle/Light Independent Reactions

See Calvin cycle animation

Light Independent Overview •  Calvin Cycle occurs in the Stroma – ATP and NADPH are used to convert 6 CO2 to glucose

– ADP and NADP+ are recycled back into the light dependent reaction

– Reactants: • CO2, ATP and NADPH

– Products: • glucose, ADP and NADP+ 20

Photosynthesis Overview

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Photosynthesis in a Nutshell: •  Light Dependent Reaction

– H2O and light go in – ATP and NADPH come out and go to the Calvin Cycle (L.I.R)

– Oxygen come out as waste •  Light Independent Reaction

– CO2 goes in – ATP and NADPH used for energy – Glucose (C6H12O6) comes out

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Factors that Affect Photosynthesis ____________________ Water is one of the raw materials needed, so A shortage of water can ________________ photosynthesis

AMOUNT OF WATER

Desert plants and conifers that live in dry conditions have a waxy coating on their leaves to prevent water loss.

slow or stop

Factors that Affect Photosynthesis

Photosynthetic enzymes function best between 0° C - 35° C

At temperatures above or below

this range, photosynthesis will slow or stop

Conifers in winter may carry out photosynthesis only occasionally

TEMPERATURE

Enzymes work BEST at a certain ___ and __________.

Conditions that are TOO ACIDIC or TOO HOT cause proteins to unwind or _________

pH temperature

DENATURE

Denaturing changes the shape of the enzyme making it not work

HOMEOSTASIS (keeping pH and temperature constant) is important for maintaining enzyme function.

Factors that Affect Photosynthesis

____________________ More light increases rate of photosynthesis up to a certain level until plant reaches its maximum rate of photosynthesis

LIGHT INTENSITY

THE BIG PICTURE PHOTOSYNTHESIS provides the _____________ we breathe and the __________ heterotrophs (like us) consume to survive

_____________ + ____________ _______________ + ____________

Carbon dioxide WATER Sugars Oxygen

OXYGEN sugars

Photosynthesis

includes

of

take place in takes place in uses

to produce to produce

use

Section 8-3

Concept Map

Photosynthesis

includes

of

take place in takes place in uses

to produce to produce

use

Light- dependent reactions

Calvin cycle

Thylakoid membranes Stroma NADPH ATP Energy from

sunlight

ATP NADPH O2 Chloroplasts High-energy sugars

Section 8-3

Concept Map