PHOTOSYNTHESIS. I. Autotrophs and Heterotrophs SUN A.Energy for living things comes from the SUN...

PHOTOSYNTHESISPHOTOSYNTHESIS

I. Autotrophs and HeterotrophsA. Energy for living things comes from the SUNSUN

B. Autotrophs- make their own food• Ex: plants, some bacteria, protists

• Heterotrophs- obtain it from the foods they consume

» Ex: animals, some bacteria, protozoans (and even fungi!)

• Sooo… food is either MADE through photosynthesis or OBTAINED through consumption

Think about the Location of Photosynthesis…

II. Location of PhotosynthesisWhich tissues contain chloroplasts?

Other Important Parts

Xylem: transports H2O

Stoma: pore that allows gases to enter and exit

A.A. Double-membrane Double-membrane structurestructure

B.B. Internal OrganizationInternal Organization

1. 1. ThylakoidsThylakoids: :

III. CHLOROPLAST STRUCTURE

a. These have a. These have clusters of clusters of chlorophyll and chlorophyll and other pigmentsother pigments

2. 2. StromaStroma: Fluid surrounding thylakoids: Fluid surrounding thylakoids

IV. Light & PigmentsA. Sunlight is “white” but contains mixtures of visible wavelengths

B. Plants gather sun’s energy using light-absorbing molecules called PIGMENTSPIGMENTS

V. Plant Pigments

Chlorophyll a - Absorbs all colors of light

except green - Plays major role in light

reactions of photosynthesis

Chlorophyll b - Yellow-green

Xanthophyll - In carotenoid family- Yellow

Carotene - Red & orange pigments

B. Visible energy spans wavelengths of approx. 400-700 nm

C. It is part of the electromagnetic spectrum

Plant pigments absorb different wavelengths of energy- which wavelength is the LEAST absorbed?

Green is NOT absorbed!

1. Leaves absorb blue-violet & red-orange light very well 2. Green light is REFLECTED which is why plants look green!

VI. PHOTOSYNTHESISVI. PHOTOSYNTHESIS

Inputs: Light, carbon dioxide, & waterInputs: Light, carbon dioxide, & water

Outputs: sugar and oxygenOutputs: sugar and oxygen

VI. Photosynthesis Has Two Parts:

VII. Light ReactionVII. Light Reaction

1.1. Chlorophyll capture light Chlorophyll capture light energy in chloroplastenergy in chloroplast

2.2. This splits HThis splits H22O into oxygen O into oxygen and hydrogenand hydrogen

3.3. Oxygen is a "waste Oxygen is a "waste product" & escapes to the product" & escapes to the atmosphereatmosphere

4.4. Energy from the reaction is Energy from the reaction is used in the next stage.used in the next stage.

B. ATP and NADP are B. ATP and NADP are recycledrecycled back back into into

the systemthe system

C. Light reaction is charging up the C. Light reaction is charging up the

““batterybattery”” needed to make needed to make

sugars in Calvin Cyclesugars in Calvin Cycle

IX. Calvin CycleIX. Calvin Cycle

• Does NOT use light at allDoes NOT use light at all• Uses energy from Light Uses energy from Light

Cycle to convert COCycle to convert CO22 into into glucoseglucose

Reactants:Reactants:

Products:Products:

Two ProcessesTwo Processes

Light ReactionLight Reaction Calvin CycleCalvin Cycle

Factors Affecting Factors Affecting PhotosynthesisPhotosynthesis

• Shortage of raw materialsShortage of raw materials• TemperatureTemperature• Light intensityLight intensity