BIOCHEMICALS PATHWAYS Photosynthesis

PHOTOSYNTHESIS PHOTOSYNTHESIS OCCURS WITHIN CHLOROPLASTS RADIANT ENERGY (SUNLIGHT) IS CONVERTED TO CHEMICAL ENERGY CHLOROPHYLL AND ENZYMES ARE INVOLVED IN THE CONVERSION

PHOTOSYNTHESIS The green colouring in chloroplasts derive from four different pigments 1Chlorophyll  green 2Chlorophyll  green 3Xanthophyll - yellow 4Carotene - orange

PHOTOSYNTHESIS The pigments appear green because 1.they reflect the green part of sunlight 2.they absorb the blue and red part of the sunlight 3.carotene reflects orange and absorbs blue light 4.xanthophyll reflects yellow and absorbs blue light

PHOTOSYNTHESIS  Chlorophyll is the most common of the plant pigments The formula is C 55 H 72 O 5 N 4 Mg It has ring structure with alternating single and double bonds

Chlorophyll Chlorophyll is found in plants and cyanobacteria Chloroplasts are organelles containing the pigment Chlorophyll is located on the surface of internal membranes

Chloroplast

Wavelengths Light has wave like properties The frequency represents the number of waves per second The units are called Hertz (Hz) The wave length is measured in nanometres metres

ABSORPTION SPECTRA

ACTION SPECTRUM Together all the pigments form the ACTION SPECTRUM

PHOTOSYNTHESIS When electrons resonate between adjacent atoms through these bonds it is said to be EXCITED The energy from the excited state becomes available for biochemical reactions however Chlorophyll  misses some of the red and blue part of the spectrum Other pigments can help absorb that light

PHOTOSYNTHESIS formula Carbon dioxide + water light + chlorophyll glucose + water + oxygen This is only the rough over all equation

PHOTOSYNTHESIS and ATP Photosynthesis is used to form the energy molecule ATP Adenosine Triphosphate

PHOTOSYNTHESIS Photosynthesis is comprised of 2 stages 1. LIGHT REACTIONS (Light dependant) 2. DARK REACTIONS (Light independent)

Light Dependant Chlorophyll traps light to produce ATP This ATP provides the energy to combine the CO 2 and hydrogen to form glucose This takes place on the internal membranes of the chloroplast Water is split producing H + Oxygen is a by-product 18 ATP molecules

Light Dependant2

Light Reaction 3

Light independent Does not require light to function It mostly occurs in the stroma Carbon dioxide diffuses into the chloroplast and becomes involved in the CALVIN CYCLE or pathway The 18 ATP molecules provide the energy to fuse 3 carbon atoms

Carbon pathways There are two Carbon Pathways C 3 and C 4 These represent the first stable Carbon molecule made in Photosynthesis C 3 has 3 carbons C 4 has 4 carbons The Calvin Cycle produces C 3

Calvin Cycle

PHOTOSYNTHESIS Reactions

Dark Reaction 1

Dark Reaction 2

PHOTOSYNTHESIS Homework