Energy Transfer - Photosynthesis Flashcards
What is the equation for photosynthesis?
6CO2 + 6H2O -> C6H12O6 + 6O2
Define a metabolic pathway
a series of enzyme controlled small reactions
Define phosphorylation
adding phosphate to a molecule
Define photophosphorylation
adding phosphate to a molecule using light
Define hydrolysis
Splitting a molecule using water
Define photolysis
Splitting of a molecule using light
Define decarboxylation
removing CO2 from a molecule
Define dehydrogenation
removing H from a molecule
Define a coenzyme
a molecule that aids enzymes
What coenzyme is used in photosynthesis?
NADP
What is the function of NADP in photosynthesis?
transfers hydrogen from one molecule to another
What are the reactions of photosynthesis?
Light dependant reaction
Light independant reaction
Where does the light dependent reaction occur?
thylakoid membrane
What absorbs light energy in photosynthesis?
photosynthetic pigments
What is the function of photosynthetic pigments?
to absorb light energy and convert it into chemical energy
what is photoionisation?
when light energy excites an electron off of an atom, creating a positive ion
what are the overall stages of the light dependent reaction?
- light energy absorbed by chlorophyll in photosystems, which then photoionises the chlorophyll as the electrons leave the molecule
- some of the energy from the electrons is used to convert ADP to ATP and reduce NADP
- ATP transfers energy and NADP transfers H to the light independent reaction
- during this H2O oxidised to O2
what happens in the light dependent reaction of photosynthesis after the water is photolysed?
electrons from water used to replace ones lost from chlorophyll
electrons from chlorophyll move down electron transport chain
energy lost is used to transport H+ into the thylakoid, forming a proton gradient
protons move down the conc gradient into the stroma via ATP synthase, causing the ATP to be formed from ADP + inorganic phosphate
how is reduced NADP formed in the light dependent reaction of photosynthesis?
light energy absorbed by PSI, exciting electrons to higher energy level
electrons transferred to NADP along with H+ from stroma to form reduced NADP
what is chemiosmosis?
movement of ions across a partially permeable membrane, down the electrochemical gradient
when is chemiosmosis used in the light dependent reaction?
when electrons flow down the electron transport chain, creating a proton gradient across the membrane to catalyse ATP synthesis
what is the light independent reaction also known as?
the calvin cycle
where does the calvin cycle take place?
the stroma of chloroplasts
what is the first stage of the calvin cycle?
carbon dioxide combined with ribulose biphosphate to form 2 molecules of glycerate 3-phosphate
what happens to the glycerate 3-phosphate generated in the first stage of the calvin cycle?
hydrolysis of ATP (from light dependent reaction) provides energy to turn it into triose phosphate
this reaction also requires protons from reduced NADP, forming NADP
what happens to triose phosphate after it is generated in the calvin cycle?
some is converted into useful organic compounds (eg glucose) and some continues in the calvin cycle to regenerate ribulose biphosphate
how is ribulose biphosphate regenerated in the calvin cycle?
5 out of the 6 triose phosphates produced are used to regenerate it
this uses the resut of the ATP produced by the light dependent reaction
how many times does the calvin cycle need to turn to produce one hexose sugar?
six
