Photosynthesis Photosynthesis and and

ChemosynthesisChemosynthesis

Energy in a cellEnergy in a cell Cells need energy to:Cells need energy to:

GrowGrow ReproduceReproduce LiveLive

Energy for these reactions can be stored in Energy for these reactions can be stored in glucoseglucose

To use energy, though, it needs to be in To use energy, though, it needs to be in molecules called molecules called ATPATP

ATP – ATP – Adenosine Adenosine TriphosphateTriphosphate

Energy – carrier moleculeEnergy – carrier molecule 3 phosphate groups3 phosphate groups Energy is released when 3Energy is released when 3rdrd phosphate phosphate

group is cut offgroup is cut off ATP ATP ADP + P + Energy ADP + P + Energy

Released energy is used to power cell Released energy is used to power cell activityactivity

Energy from the Energy from the SunSun Some organisms gain energy Some organisms gain energy

from consuming other from consuming other organisms – called organisms – called heterotrophsheterotrophs

Other organisms can make their own food Other organisms can make their own food – called – called autotrophsautotrophs Plants, algae, and some bacteria capture Plants, algae, and some bacteria capture

about 1% of the sun’s energy about 1% of the sun’s energy convert it to chemical energy through the convert it to chemical energy through the

process of photosynthesisprocess of photosynthesis

Photosynthesis Photosynthesis EquationEquation

LIGHTLIGHT

6CO6CO2 2 + 6H+ 6H22O CO C66HH1212OO66 + 6O + 6O22

Occurs in the Occurs in the

chloroplast of plant cellschloroplast of plant cells

Chloroplast StructureChloroplast Structure

•Little “coin-like” structures called Thylakoids

•Membrane surrounding thylakoids contains chlorophyll

•Stacks of Thylakoids called Grana

•Space surrounding Grana is called the Stroma

Photosynthesis VideoPhotosynthesis Video

Stages of PhotosynthesisStages of Photosynthesis

1.Light Reactions

2. Light-Independent Reactions (Calvin Cycle)

Stages of PhotosynthesisStages of Photosynthesis

1. The Light Reactions1. The Light Reactions Light energy is absorbed and converted Light energy is absorbed and converted

to chemical energy in the bonds of ATP. to chemical energy in the bonds of ATP. 1. Light strikes electrons in the chlorophyll1. Light strikes electrons in the chlorophyll

2. Energy from excited electrons used to make 2. Energy from excited electrons used to make ATP moleculesATP molecules

3. Energy now available to do work.3. Energy now available to do work.

Light Reactions…Light Reactions…

Water is split into hydrogen ions, oxygen, Water is split into hydrogen ions, oxygen, and electronsand electrons Electrons replace those lost by the Electrons replace those lost by the

chlorophyll moleculechlorophyll molecule Oxygen is given off as wasteOxygen is given off as waste Hydrogen ions are used to create NADPH Hydrogen ions are used to create NADPH

(another energy carrier molecule) for use in (another energy carrier molecule) for use in later steps of photosynthesislater steps of photosynthesis

Calvin Cycle Calvin Cycle Light – Independent Light – Independent reactionsreactions The ‘synthesis’ part of The ‘synthesis’ part of

photosynthesisphotosynthesis Takes place in the stroma Takes place in the stroma

of the chloroplastof the chloroplast Uses ATP and NADPH Uses ATP and NADPH

from light reactionsfrom light reactions Enzymes combine COEnzymes combine CO22 with with

hydrogen (from NADPH) and hydrogen (from NADPH) and energy from ATPenergy from ATP

Light Light EnergyEnergy

Light energy has different wavelengths – we Light energy has different wavelengths – we see them as different colorssee them as different colors

PigmentPigment – a protein that absorbs light – a protein that absorbs light ChlorophyllChlorophyll – a pigment in the chloroplast – a pigment in the chloroplast

Absorbs red and blue lightAbsorbs red and blue light Reflects green and yellow light – we see that reflected light.Reflects green and yellow light – we see that reflected light.

CarotenoidsCarotenoids – pigments that make plants yellow and – pigments that make plants yellow and red in the fallred in the fall

ROY G. BIV

ChemosynthesisChemosynthesis

Similar to Similar to Photosynthesis – but no Photosynthesis – but no light!light!

Inorganic compounds Inorganic compounds are used for energy to are used for energy to make sugarsmake sugars

Ex: bacteria can do this Ex: bacteria can do this in the hydrothermal in the hydrothermal vents at the bottom of vents at the bottom of the oceanthe ocean

Chemosynthesis VideoChemosynthesis Video