What is the difference between an autotroph and a heterotroph?

Why do plants need sunlight?

What gases are exchanged between plants and animals?

To be able to list the inputs and outputs of photosynthesis.

To be able to identify the structures in a chloroplast.

To be able to summarize light-dependent reactions.

Light energy ------> chemical energy

Used by autotrophs to produce food

All of our energy starts as light energy! Plants use sunlight to make food animals

eat plants other animals those animals

Photosynthetic OrganismsGo through Photosynthesis to

produce GLUCOSE…Autotrophs “Producers” in the food webConsist of plants, protists,

cyanobacteria

1) Light dependent Light energy is absorbed and converted

into chemical energy in the form of ATP and NADPH. (also produces Oxygen!)

2) Light Independent (Calvin Cycle) CO2 ATP and NADPH are used to make

glucose. *Glucose is the basic building block for more complex sugars

such as starch.*

Glucose

Thylakoids: flattened sac-like membranes arranged in

stacks (stacks are called grana). Light-dependent reactions take place here. Electron transport occurs in the thylakoid

membrane

Stroma: Fluid filled space outside the grana. Light-independent reactions take place

here.

Step 1: Light energy reaches photosytem II causing the water molecule to split

OHH

H2O

H+O2+

*H+ is released to the electron transport system.* O2 is given off as a byproduct.

Step 2: Light energy reaches photosystem I and electrons flow from photosystem II to photosystem I. (to replace the electrons lost)

Step 3: Hydrogen ions (protons) are pumped across the membrane as the electrons fall. (think of a hyper child losing energy)

Step 4: Electrons from photosystem I move to a protein called ferrodoxin.

**Ferrodoxin = “helper” protein**

Step 5: Ferrodoxin transfers electrons to NADP+ forming NADPH. (We need this for the next part of photosynthesis!)

Step 6: Hydrogen ions move through the ATP Synthase because of the concentration gradient, creating ATP. (Chemiosmosis) To Calvin Cycle

Lets see it altogether now!

http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html

What goes into a light dependent reaction?

What is the goal of a light dependent reaction?

What is given off as a byproduct?

What is the name of the protein needed in a light dependent reaction?

Do Now

In what part of the chloroplast do light reactions occur?

What are the outputs of light-dependent reactions?

What is the name of the cycle in light-independent reactions?

Objectives

List the inputs and outputs of the Calvin Cycle

Define chemiosmosis and it’s role in photosynthesis.

Summarize light – independent reactions

Perform chromatography to identify the pigments of green leaves.

Calvin Cycle

Takes place in the stromaUses NADPH and ATP from Phase I

(light dependent reactions)Needs CO2!!!Produces GLUCOSE

Calvin Cycle

Functions like a sugar factory within a chloroplast

**Regenerates the starting material with each turn

Calvin Cycle

Inputs

- ATP- NADPH- CO2

Outputs

- Glucose

Calvin Cycle

Chemosynthesis

Mechanism in which ATP is produced as a result from the flow of electrons down a concentration gradient.

Ex: Light reactions (H+ ions and ATP synthase)

Alternative Pathways

Light and Water can limit the amount of photosynthesis a plant can perform.

Some plants develop alternate pathways to maximize energy conservation.

Ex: CAM and C4 plants.

Animation

http://www.science.smith.edu/departments/Biology/Bio231/calvin.html