Chapter 10 photosynthesis

Autotroph

self feeder, utilizes photosynthesis 

• PRODUCERS

Heterotrophs

feeds on other organisms 

• CONSUMERS/DECOMPOSERS

Stroma

space inside double membrane

• Site of calvin cycle

Thykaloid

3rd membrane system suspended in stroma

• Contain chlorophyll 

• Granum = stack of thykaloid (like poker chips)

Absorption spectrum

graph plotting pigment rather than wavelength (rainbow)

Spectrophotometer

machine that passes individual wavelengths of light through a solution and measures light transmitted (measures absorption)

Reduced

(hydrogen) electrons are added 

• CO2 (carbon dioxide is reduced)

Oxidized

stripping hydrogen

• Water is oxidized 

Endergonic

photosynthesis is this redox reaction

• Requires input of energy

Why is photosynthesis so important?

Converts light energy to chemical energy which is stored in sugars or other organic compounds

Where does photosynthesis occur?

Any green part of a plant, but leaves mainly  

Mesophyll

middle layer of plant

Stomata

pores on plant 

• Where gas exchange occurs/ water balance

Important structures of chloroplasts

• Stroma

• Thykaloids

• Granum 

Light absorption

light absorbed will transfer energy by exciting electrons

Light reflection

 light reflected results in perceived color of that object

Carotenoids

pigments in chloroplasts that broaden the spectrum of absorbed light

• May absorb excess light energy to prevent production of oxygen radicals

Ground state

LOW potential energy

Excited state

HIGH potential energy

ground state

atoms absorb energy from the environment, electrons move from an electron shell with Low Potential energy

excited state

move to an electron shell with Higher potential energy

What's released when electrons return to ground state?

Energy

What happens when electrons return to the ground state in the chlorophyll of plants?

is it not released as light, it passes energy from one chlorophyll to the next 

first part of photosynthesis

Light reactions

where do light reactions happen?

thylakoid membranes

Light reactions use sunlight and water to:

Make ATP, Make NADPH, Release oxygen as a leftover product

photosystems

groups of pigments and proteins that capture sunlight

light reactions in 8 steps

Photosystem II absorbs sunlight

An electron acceptor catches the energized electrons

Water splits to replace the missing electrons

Electrons travel through an electron transport chain

The buildup of H⁺ helps make ATP

Photosystem I absorbs more sunlight

The electrons pass to another carrier

NADPH is made

Calvin cycle main goal

uses CO₂, ATP, and NADPH to make G3P, a small sugar used to build glucose and other molecules. It happens in the stroma, the fluid inside chloroplasts

3 phases of the Calvin cycle

1. Carbon fixation — brings carbon into the cycle

2. Reduction — makes G3P

3. Regeneration — rebuilds the starting molecule