L6 Photosynthesis - Light Reactions

What is the main role of photosynthesis?

To convert CO2 and H2O into carbohydrates

What is solar energy captured as during photosynthesis?

ATP and NADH

What do ATP and NADH do to CO2 in photosynthesis?

Convert it into hexose phosphate

What are the main features of photosynthesis light reactions?

membrane bound
release O2 from H2O
H+ used for chemiosmotic synthesis of ATP and hydride, reducing NADP to NADPH

What are the main features of photosynthesis dark reactions?

occur in solution
reduce CO2 to carbohydrates
require energy of NADH and ATP

What size are chloroplasts generally?

4-8mm

What are the main structural features of chloroplasts?

internal membrane stacking
two surrounding membranes
crucial orientation of thylacoids (reaction changes their direction)

What is the most abundant pigment in plants on earth?

Chlorophyll

What are the different types of chlorophyll?

Chlorophyll a and Chlorophyll b

Do the two types of chlorophyll have similar structures?

Yes

What allows pigments to absorb many wavelengths of light?

Spread electrons in a 2D plane

What are the different pigments found in plant cells?

carotenoids, phycogyanin, phycoerythin, chlorophyll a and b

What extends the range of light capture?

Antenna pigments

How do antenna pigments and chlorophyll capture light energy?

Exchange light energy (excited electrons) until captured

What is done with energy once it is captured by antenna pigments and chlorophyll

It stored until energy is ready to be used in a reaction centre

What is energy used for photosynthesis?

Splitting H2O

What is the “Z” scheme?

Electrons are pushed into energy state from photosynthesis to excited state and then to the 2nd photosystem. The electrons are then pushed back to their excited state.

What wavelength does photosystem 1 absorb?

700

What wavelength does photosystem 2 absorb?

680

What is embedded in the thykaloid membrane?

Many proteins and pigments

What are photosystems 1 and 2 connected by?

cytochrome bf complex

In the photosystems, where are electrons conducted to?

From H2O to NADP+

What are the reaction steps in light photosynthesis?

Electrons move across the membrane, H+ is moved and electrons return

What is the proton electrochemical gradient used to create?

ATP

What is the direction of electron flow in the Z scheme?

Uphill electron flow

What does the Z scheme do to the potential of components?

Reduces potential of components

What type of ring does chlorophyll contain and what is in this ring?

tetrapyrrole ring (cholin) containing Mg2+