Biology Unit 2: Light dependent

Parts of photosynthesis

Light dependent reactions and light independet reactions

Where does light-dependent reactions take place

Thylakoid

Where does light-independent reactions take place

Stroma

What cycle happens in the light independent part

Calvin cycle

What are photosystems

2 proteins complezes that convert solar energy to chemical energy

Where are photosystems found

In the Thylakoid

What does photosystems allow chlorophyll to do

allows it to absorb at different wavelengths

What wavelength of light can photosystem 2 absorb

680 nm

What wavelength of light can photosystem 1 absorb

700 nm

First step involving photosystems

Light energy makes a water molecule split and release an electron

Second step involving photosystems

The electron travels through a chain of proteins

What are these chains of proteins in the second step of photosystems

1. Plastoquinone

2. cytochrome c

3. plastocyanin

Third step

Electron ends up in photosystem 1 and is renergized by light energy

Last step

goes through ferredoxin and a reductase that reduces NADP+ to NADPH

How is ATP synthase involved in photosystems

As the electron is move through cytochrome C, their energy pumps protons that flow out of the thylakoid apce through ATP synthase, this makes the enzyme spin and ADP + Pi is turned to ATP

How is light abosrbed

Through packets of energy called photons that have specefic amounts of energy

Each wavelength is associated…

with photons of distinct amount of energy

Longer wavelength means…

smaller amounts of energy

An atom can only abosrob a photon if…

they have the exactly the right amount of energy

Pigment

Compound that absorbs certain wavelengths of visible light while reflecting others

Photosynthetic pigments

trap light energy to pass on

What does the pumping of prtons create and how does it allow prtons to move through the atp synthase

Creates an electro chemical gradient and protons move against the gradient through AtP synthase

Noncyclic photophosphorylaiton

bassically then entire photosystem cycle that makes atp and NADPH

Cyclic photophosporylation

Bassically the just the system invlocing photosysystem 1, when the electrons get excited in PS1 and travel through through ferredoxin and a chain of electron acceptors, but when it reaches cytochrome c, the electrons go back to the cytochrome c just before it gives the elctrons to ps1

Result of cyclic photophosphorylation

produces only atp

Other characteristics of cyclic photophosphorylation

1. happens at the same time of noncyclic photophosphorylation

2. faster production of ATP

Photoexcitation

When photosystems absorb light that causes elctrons to higher energy states