Lesson 5: Photosynthesis

PHOTOSYNTHESIS

• is a place in which light energy from the sun is changed to chemical energy

• two stages: the light dependent reactions & calvin cycle

AUTOTROPHS

• greek works, auto meaning “Self and trophein meaning “Feeding”

• organisms that are able to obtain energy from sunlight or inorganic susbtances

PHOTOTROPHIC

• obtaining energy from sunlight

• produced food through photosynthesis

CHEMOTROPHIC

• obtaining energy from inorganic substances

• produces food through chemosynthesis

HETEROTROPHS

• greek work, hetero meaning “different” and trophein meaning “feeding”

• get food b benefiting from autotrophs

THE PROCESS OF PHOTOSYNTHESIS

• starts n the leaves and the roots of a plant

• the leaves serve as the collection of solar energy and carbon dioxide

• the roots, as the entrance of water and other minerals

• sugar and oxygen, products of photosynthesis

• carbon dioxide, not being able to pass through the cuticle of the leaves, enters the plant through the stoma (stomata), bordered by guard cells

• the water from the roots is transported to the leaves through xylem vessels

• all of these raw materials are then stored and processed in the cell

• the sunlight needed for photosynthesis is then forwarded to the cell’s chloroplasts

CHLOROPHYLL

• a pigment that reflects green light, which then results in the green color of plants

1.CHLOROPHYLL A
2.CHLOROPHYLL B

• two types of chlorophyll

CHLOROPHYLL A

• the main photosynthetic pigment which converts light energy into chemical energy

CHLOROPHYLL B

• secondary photosynthetic pigment which is more inclined to absorbing light energy towards the green wavelength

CAROTENOID

• which absorbs the green and blue parts of the light spectrum

• plants that are rich in this appear yellow, orange, or red

THYLAKOID MEMBRANES

• contain different protein complexes, such as photosystem I, photosystem II, ATP synthase

CHLOROPLASTS

• play a big role in photosynthesis because the light energy that strikes the thylakoid membranes stimulates the chlorophyll inside it, causing the pigments to lose electrons

• these electrons then enter the electron transport chain, which fuels the phosphorylation of ADP to ATP, converting light energy to chemical energy

1.STAGE 1 (LIGHT DEPENDT)
2. STAGE 3 (CALCIN CYCLE/LIGHT INDEPENDENT)

• stages of photosynthesis

• 6CO2 + 6H20 + LIGHT ENERGY → C6H1206 + 602

STAGE 1 (LIGHT DEPENDENT)

• the reactions takes place in the thylakoid membranes

• the reactions capture energy from sunlight, which changed to chemical energy stores in molecules of NADPH and ATP

1.CARBON FIXATION
2.REDUCTION
3.REGENERATION

• stage 2 (carbon cycle/light independent)

CARBON FIXATION

• the carbon (from carbon dioxide in the atmosphere) is added to a single five-carbon molecule called RUbP (Riboluse phosphate)

REDUCTION

• these reactions use chemical energy from NADPH and ATP that have been produced in the light reactions

• the final product of the calvin cycle is glucose