Photosynthesis

heterotrophs

organisms that eat other organisms to get nutrients/organic molecules

autotrophs

organisms that produce their own organic molecules from inorganic molecules

photoautotrophs

autotrophs that use light energy to obtain organic molecules from inorganic molecules

photosynthesis equation

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

oxidation

where a molecule loses hydrogen atoms (aka protons)

reduction

where a molecule gains hydrogen atoms (aka protons)

OILRIG

Oxidation Is Losing (hydrogen atoms), Reduction Is Gaining (hydrogen atoms)

light-dependent reaction overview

where energy from the sun is used to split water, creating oxygen as a byproduct, electrons, and protons

• produces ATP and NADPH that is used in the light-independent reactions

light-independent reaction (Calvin Cycle) overview

where the ATP and NADPH from the light-dependent reactions are used to make sugars with CO₂.

• produces ADP + Pi and NADP+ to be recycled back into the light dependent reactions so photosynthesis can continue

where does photosynthesis occur in plants?

inside chloroplasts

What is the liquid inside the chloroplasts’ inner membrane where light independent reactions take place?

stroma

what are the stacks of membranous sacs located in the stroma called?

grana (or granum)

what are grana made of?

sacs called thylakoidswha

what part of photosynthesis happens in thylakoids?

light dependent reactions

photophosphorylation

when light energy is used in ATP synthesis

• light energy excites electrons in the chloroplast, forcing them to higher energy levels

• the electrons release energy as they move through the chloroplast

• NAD+ accepts the electrons at the end and becomes NADPH

what is the last electron acceptor in the light dependent reactions

NADP+ (which gets turned into NADPH)

chlorophyll

pigment found in chloroplasts that absorbs light energy from the sun

photolysis

the formation of a proton gradient by the splitting of water molecules into hydrogen atoms and electrons for the purpose of making an electron transport chain (ETC); driven by light energy

ATP synthase

enzyme used to make ATP, powered by the proton gradient created by photolysis and the ETC

chemiosmosis

the process of using a proton gradient and ATP synthase to make ATP

What is another name for Light-Independent Reactions?

the Calvin Cycle

what are the steps of the Calvin Cycle?

1. fixation of carbon

2. reduction

3. regeneration (of RuBP)

Fixation of carbon

where the enzyme known as Rubisco fixes a carbon molecule by adding a carbon molecule to the 5-carbon molecule RuBP, forming a 6-carbon molecule; breaks down into 2 three-carbon molecules to become stable

• Rubisco = ribulose-bisphosphate-carboxylase

• RuBP = ribulose-bisphosphate

reduction

where the ATP and NADPH produced by the light-dep reaction reduce the 3 carbon molecules produced by the fixation of carbon

• produces G3P = glyceraldehyde-3-phosphate

  • can be made into sugars or recycled in the regeneration step

regeneration of RuBP

RuBP must be regenerated in order for the Calvin Cycle to continue

5 G3P= 15 carbon molecules

• ATP from the light dep reaction rearranges the G3P molecules to form 5 RuBP