Ivan_Lujan_Block5_MM5

Conversion of light energy to chemical energy of food

Chloroplasts

Structure

Chlorophyll

Stroma

Thylakoids

Green pigment in plants

Envelope of two membranes

Stacks of interconnected membranes

Function

Help convert light energy to energy for plants

Sight of photosynthesis

Photosynthetic equation

6CO2 + 6H2O + light energy = C6H12O6 + 6O2.

Reactants

Products

Carbon dioxide, water, and light energy

glucose and water

Splitting of water

Oxygen is derived from water

Spit by chloroplasts

Splits water

Redox process

Electron flow is reverse from Cellular respiartion

Two Stages of Photosynthesis

Gain potential energy as it is a catabolic reaction

Light reactions

Calvin cycle

Convert solar energy to chemical energy

Reduces fixed carbon to carbohydrate

Absorbed by chlorophyll

NADP+ fucntions as an electron carrier

Reduced to NADPH by electrons and Hydrogen

Generate ATP

Reducing power given by NADPH

Requires ATP

Light Reactions in depth

Sunlight

Belongs to visible light spectrum

Transmits particles known as photons

contain fixed energy

Light receptors

Different pigments absorb different lights

Spectrophotometer

The ability of a pigment to absorb various wavelengths

absorption spectrum show light absorption from pigments

Excitation of Chlorophyll by light

Electrons move to a higher state when absorption of photons occur

Energy lost as heat

Photosystem

A reaction center surrounded by a number of light harvesting complexes

Each consists of a pigment molecules bound to particular proteins

Reaction center

Protein complex that includes two special chlorophyll a molecules and a molecule called the primary electron accpetor

Photosystem 1 and 2

Found in Thylakoid membranes

Noncylic electron flow

Light energizes the two photosystems to drive the synthesis of NADPH and ATP

Two possible routes for electron flow

Noncylic

Cyclic

Prodominate route

Photon strikes

Electron picked by primary

enzyme splits water molecule

Forms O2

Exergonic fall of electrons provides energy for ATP

Photoexcited electrons from chain then carried by NADP+ to form NADPH

use only Photosystem 1

Short circut

Only generates ATP

Underwent when high levels of NADPH

The Calvin Cycle in depth

Anabolic process

Carbon enters in form of CO2

each attaches to a five carbon sugar named ribose

Forms six carbon intermediate unstable

Splits to two molecules of 3-phophoglycerate

Each molecule receives a phosphate from ATP

NADPH reduces it to G3P

Stores potential energy

Carbon skeletons are rearranged into three molecules of RuBP

via ATP

G3P then used as a starting block fro glucose