5: Energy Transfers Flashcards
What is the balanced symbol equation for photosynthesis?
6CO2(g) + 6H2O(l) -> 6O2(g) +C6H12O6
How is the chloroplast structure adapted to their fucntion?
- have stacks of thylakoids (grana), providing a large surface area for attatching chlorphyll, electrons and enzymes
- network or proteins in grana hold chlorophyll in a orientation to absorb more light
- granal membranes have ATP sunthase channels which are selectively permeable to create a proton gradient
- have DNA and ribosomes to synthesise proteins
What is oxidation and reduction?
oxidation- when a substance loses elctrons, lose H+
reduction- when a substance gains electrons, gain H+
What is a photosystem?
- funnel-like structures in the thylakoid membrane
- made from accesory pigments (cluster), absorbing light energy to transfer it to primary pigment reaction centre (chlorophyll)
- energy funneled tor eaction centre causes photoionisation of chlorophyll, loss of an electron
What is the role of coenzymes?
pick up and provide hydrogen atoms to complete a reaction and make a substance
What is the first stage of photosynthesis?
Light Dependent Reaction:
- chlorophyll / photosystem absorbs light;
- electron lost by chlorophyll in photoionisation
- splitting of water / photolysis replaces electron;
- passing of excited electrons between chlorophyll molecules in photosystems;
- electron passed from photosystem II to carriers (in thylakoid membrane);
- production of ATP in this way is called photophosphorylation;
- electron causes pumping of protons into the thylakoid;
- proton gradient used by ATPase to drive ATP production;
- electron passes to photosystem I at end of carrier chain;
- electron re-excited and emitted by photosystem I;
- electron passed to / used to reduce NADP+;
- NADPH + H+ / reduced NADP produced;
- cyclic photophosphorylation using photosystem I, electron carriers and ATPase only;
What is the second stage of photosynthesis?
Light Independent Reaction: Calvin Cycle
- light-independent reaction fixes CO2;
- to make glycerate 3-phosphate;
- glycerate 3-phosphate / GP / phosphoglyceric acid becomes reduced;
- to triose phosphate / phosphoglyceraldehyde / glyceraldehyde 3-phosphate;
- using NADPH;
- using ATP;
- ATP needed to regenerate RuBP;
- ATP is made in light-dependent reactions;
- light causes photoactivation / excitation of electrons;
- flow of electrons causes pumping of protons into thylakoid;
- ATP formation when protons pass back across thylakoid membrane;
- electrons are passed to NADP / NADP+;
- NADPH produced in the light dependent reactions;
What are the limiting factors of photosynthesis?
- light intensity- graph increases then plateaus
- CO2 concentration- graph increases then plateaus
- temperature- graph increases then decreases (as enzyme denatures)
What is the balanced symbol equation for respiration?
6O2(g) +C6H12O6 -> 6CO2(g) + 6H2O(l)
How is the mitochondria structure adapted to their fucntion?
- rod shaped organelles, 0.5-1μm
- site of aerobic respiration in eukaryotic cells, synthesises ATP
- organelles: matrix, cristae, ribosomes, circular DNA
- double membrane structure, with an inner layer with many folds to create a high surface area
Why is respiration important?
- provides energy required for condensation ADP-> ATP
- for each 30.5kJmol-1 of energy released by hydrolysis of ATP, the same energy must also be input from respiration to reform ATP
- energy from condensation reaction comes from chemical energy in glucose
- releases small packets of energy to prevent cell damage so minimal energy is wasted
