Cellular Energy

Photosynthesis

Energy in Living Systems

All organisms need energy to survive The sun is the first and largest source of

energy Autotrophs

• Photsynthesizing organisms gather their OWN energy from the sun.

Heterotrophs• Organisms that gather energy from other organisms

Flow of Energy

Metabolism

Metabolism• Set of all chemical reactions that occur in the body

• Chemical Reactions

• Processes that result in the changing of substances

• For example the breaking of a water molecule into a hydrogen and hydroxide ion is a chemical reaction

• H2O H+ + OH-

• Most of the energy that drives metabolism is supplied by adenosine triphosphate (ATP)

ATP – Adenosine Triphosphate

Energy currency - “Energy Money” in the cell In cells

• Some of the chemical energy stored in food molecules is released as heat.

• The remaining energy is stored temporarily as Adenosine triphosphate (ATP)

• Like money, ATP is portable form of energy.

• ATP flows from chemical reaction to chemical reaction delivering energy wherever the cell needs it

How does ATP deliver energy? Adenosine TRI(3)phosphate (ATP) has a 3 phosphate tail which is

very unstable During a chemical reaction ATP will give up one of it’s phosphates and

as a result energy is delivered. Adenosine TRIphosphate (3 phosphate) then turns into Adenosine DIphosphate (2 phospates).

Without ATP’s energy delivery the body’s chemical reactions would occur so slowly that the body could not survive.

Photosynthesis – Sun Energy

The process that provides energy for almost all life Steps

• Energy is captured from the sunlight

• Light energy is converted to chemical energy which is temporarily stored in ATP and NADPH

• NADPH is “energy money” that delivers energy much like ATP.

• The chemical energy stored in ATP and NADPH powers the formation of organic compounds, using carbon dioxide

1st Step – Absorption of Light Energy

Plant cells have chloroplasts (chloro = green, plast = living material)

Chloroplasts contain stacks of thylakoids whose membranes contain light absorbing pigments.

Chlorophyll Chlorophyll (chloro =

green, -phyll = leaf) is the primary pigment.• Chlorophyll absorbs the

wavelengths for blue and red light while reflects the wavelengths for green and yellow light.

• This is why leaves look green.

Chlorophyll pigments in the thylakoid membranes capture the energy from the sun

2nd Step – Conversion of Light Energy Electron Transport Chain

• The electron transport chain is what is sounds like• This is a transport system that consists of pigments in the

thylakoid membranes whose purpose is to temporarily store energy in the form of ATP and NADPH

• This energy is crucial to the 3rd step of photosynthesis

3rd Step – Storage of Energy

1st Step – Needs Light• Capture energy from the sun

2nd Step – Needs Light• Temporarily store energy as ATP and NADPH

3rd Step- No Light Required• Use ATP and NADPH to create organic

molecules the cell can use or store as energy

3rd Step – Calvin Cycle

Calvin Cycle• Most common method

of Carbon fixation• Carbon Dioxide

Fixation• Using Carbon

Dioxide to make organic compounds

• The organic compounds are required for the plant cell’s survival

Wrap-Up The ingredients are light,

carbon dioxide and water the end result is sugar and oxygen (which is released into the atmosphere)

Photosynthesis can be wrapped up in 3 steps• Light energy captured from

the sun

• Energy stored in ATP/NADPH

• ATP/NADPH and Carbon Dioxide used to make organic compounds needed for the plant cell’s survival.