Photosynthesis Chapter 6

6.1 Vocabulary Photosynthesis – Light-dependent reactions – Calvin Cycle – Light-Independent reactions –

Photosynthesis in nature Autotrophs: biotic producers; make their own food photoautotrophs; chemoautotrophs Heterotrophs: biotic consumers; obtain organic food by eating other organisms or their by-products (includes decomposers)

6.1 An Overview of Photosynthesis Show Photosynthesis Video

6.1 Life is powered by sunshine. Energy from the sun is captured by plants, algae, and certain bacteria using photosynthesis. 1% of all energy on earth is captured by photosynthesis, and provides all energy which drives everything.

The chloroplast Sites of photosynthesis Double membrane Pigment: chlorophyll (located in the thylakoid) Light dependent reactions occur in the thylakoid Light independent reactions occur in the stroma

Pigments Chlorophyll pigments absorb blue and red but reflect green. Carotenoid pigments absorb violet and blue but reflect yellow, orange, and red.

Why Photosynthesis?

Light Dependent/Independent Reactions

Photosynthesis: an overview The light-dependent reactions convert light energy into chemical energy (ATP). The molecules of ATP produced in the light-dependent reactions are then used to fuel the light-independent reactions that produce simple sugars. 6CO2 + 6H2O → C6H12O6 + 6O2

6.1 Sum It All Up! Photosynthesis uses energy from sunlight to power the synthesis of organic molecules from CO2 in the air. In plants, photosynthesis takes place in specialized compartments within chloroplasts.

6.2 Vocab Pigments – Carotenoids -

6.2 Sum It All Up! Plants use pigments like chlorophyll to capture photos of blue and red light, reflecting photons of green wavelengths. Why do the leaves on a tree change color in the fall?

Light Dependent Reactions Stage 1 & Stage 2 Located in the thylakoid membrane Pigment molecules are struck by light and give off an electron Excited e- is trapped by a primary e- acceptor and sent through the electron transport chain Electron transport produces ATP e- is replaced by splitting water (releases O2) Produces ATP & NADPH

Light Independent Reactions Stage 3 (final stage) Also called the Calvin Cycle Occurs in the stroma of the chloroplast 3 molecules of CO2 are converted into glyceraldehyde 3-phosphate (G3P) G3P can then be used by the plant to make glucose and other organic compounds

Calvin cycle

How Autotrophs Use Intermediates and Products of Photosynthesis Sugar phosphates are used as cellular fuel and as building blocks in synthesis of carbohydrates Sucrose is transported from leaves to all parts of the plant Starch is the main storage form of carbohydrate in plants

A review of photosynthesis