Chapter 7 - photosynthesis (freestyle notes:)

7.1 Photosynthetic Organisms

• ALL LIFE ON EARTH DEPENDS ON SOLAR ENERGY!!

• Photosynthetic organisms transform solar energy into chemical energy

• Photosynthetic organisms include: Plants, algae, and cyanobacteria (AUTOTROPHS)

AUTOTROPHS (aka Producers) - organisms that produce their own food through the synthesization of carbohydrates (photosynthesis) to also feed consumers too. (Basis of ALL food chains)

HETEROTROPHS (aka Consumers) - relies on consuming other organisms for energy and nutrients, unable to produce their own food.

• Examples of heterotrophs include animals, fungi, and most bacteria

***BOTH use the organic molecules produced through photosynthesis as building blocks for growth, and repair, and as a source of chemical energy for cellular work.***

PHOTOSYNTHESIS - the process by which autotrophs convert solar energy into chemical energy (carbohydrates!!!), specifically glucose, using sunlight, carbon dioxide, and water.

• Produces large amounts of oxygen gas (O2)

• Oxygen feeds cellular respiration

MORE ON PHOTOSYNTHESIS:

Takes place on the ¨green¨ portion of plants

• The leaf of the plant contains mesophyll tissue (MESO— MIDDLE) - Located between the upper ***upper surface of leaf*** and lower epidermis ***bottom surface of leaf***

• Cells in the mesophyll containing chloroplasts

• RAW MATERIALS (reactants) FOR PHOTOSYNTHESIS ARE CO2 + WATER

• Roots absorb water that moves up the vascular tissue (leaf veins)

STOMATA - small opening in which carbon dioxide enters through in the leaf.

• Diffusion takes place in the chloroplast which consist of 2 parts: The GRANA and the STROMATA

GRANA - made up of thylakoids (membranous disks) that contain pigments like chlorophyll which absorb solar energy.

STROMATA - semi-fluid interior where CO2 is enzymatically reduced to a carbohydrate.

Photosynthesis Reaction

2 part process…

1. LIGHT DEPENDENT REACTION - the first stage of photosynthesis that requires sunlight, where light energy is captured by chlorophyll and converted into chemical energy in the form of ATP and NADPH.

2. DARK REACTION (Calvin Cycle) - the second stage of photosynthesis that does not require light, where the ATP and NADPH produced in the light-dependent reactions are used to convert carbon dioxide into glucose through a series of enzymatic reactions.