Topic 8: Metabolism, Cell Respiration and Photosynthesis

● Energy

________ released by protons moving through ATP synthase is used to phosphorylate ATP.

four carbon compound

O The ________ undergoes further oxidation and one molecule of NAD+ is reduced to NAD.

Oxidative phosphorylation

________ occurs in the inner mitochondrial membrane.

Carbon

________ fixation: In the LIR, a carboxylase catalyses the carboxylation of ribulose- biphosphate.

waste products

This is one of the ________ of respiration, and contributes to the proton gradient and H+ ions are being removed from the matrix.

Chemiosmosis

________: NADH+H+ supplies pairs of hydrogen atoms to the first carrier in the chain.

Photoactivation

________: Absorption of light by photosystems generates excited electrons.

Calvin cycle

● 1 RuBp molecule is carboxylated in one turn of the ________.

Stroma

________ contain all the enzymes required.

chemical form

This allows energy, instead of being lost as heat, to remain in ________ and be used in oxidative phosphorylation.

O NO2+05O2

________=> NO3 Phosphorylation: ● Phosphorylation makes the phosphorylated molecule unstable.

▪ Isoleucine

________ acts as a non- competitive inhibitor by binding to the active site of the first enzyme in the chain- threonine dehydratase.

Electron transport chain

________: Transfer of excited electrons occurs between carriers in thylakoid membranes.

RuBP regeneration

________: RuBP is reformed using ATP.

Photolysis

________ leads to the production of oxygen.

Glycolysis

________ and ATP: Glycolysis gives a small net gain of ATP without the use of oxygen.

substrate concentration

O Increasing ________ can overpower inhibitor and restore full capacity.

role of oxygen

The ________: Oxygen is needed to bind with the free protons to form water to maintain the hydrogen gradient.

O Chlorophyll

________ in the reaction centres, after reducing plastoquinone, are oxidised by inducing photolysis.

Photon gradient

________: Excited electrons from PSII are used to generate a proton gradient.

Sulfadiazine

________ binds to dihydropteroate synthetase and in doing so blocks para- aminobenzoate.

Light dependent reactions

________ take place in the thylakoid space and across the thylakoid membranes.

Chemiosmosis

________: ATP synthase in thylakoids generates ATP using the proton gradient.

Enzymes and activation energy

● Enzymes lower the activation energy of the chemical reactions that they catalyse

● Non competitive inhibition

o Inhibitor binds to the allosteric site distorting the active site

● End-product inhibition

o Substance that binds to the allosteric site is the end product of the pathway (in some cases); this acts as an inhibitor so the pathway can be switched off to stop excess product generation

▪ Isoleucine acts as a non-competitive inhibitor by binding to the active site of the first enzyme in the chain

threonine dehydratase

o NO2+0.5O2 => NO3 Phosphorylation

● Phosphorylation makes the phosphorylated molecule unstable

● Adds phosphate group (PO4)3

‘activates the molecule

Glycolysis and ATP

● Glycolysis gives a small net gain of ATP without the use of oxygen

● Metabolic pathway

o Glucose

The link reaction

● Pyruvate is converted into acetyl coenzyme A

The Krebs cycle

● Final breakdown of glucose molecule

● Outline of the Krebs cycle

o Acetyl CoA carboxylates oxaloacetate to form a 6 carbon compound (citric acid/citrate) o Citrate is decarboxylated, forming carbon dioxide, and oxidised to create a molecule of reduced NAD

Chemiosmosis

● NADH+H+ supplies pairs of hydrogen atoms to the first carrier in the chain

The role of oxygen

● Oxygen is needed to bind with the free protons to form water to maintain the hydrogen gradient

Structure and function of mitochondria

● Semi-autonomous organelle

Products of the light-dependent reaction

● NADP and ATP are produced in the LDR

● Light energy => chemical energy (ATP) and NADPH+H+ Location of the light-independent reactions

● Light independent reactions take place in the stroma

Photoactivation

● Absorption of light by photosystems generates excited electrons

● Photosystems

chlorophyll and accessory pigments groups together

● Located in thylakoids; two photosystems

PSI and PSII

o First electron acceptor

plastoquinone

▪ Hydrophobic

stays within the membrane

o This processes occurs twice so PSII loses 4 electrons and two reduced plastoquinones are created Photolysis

● Photolysis of water provides electrons for use in the LDR

Electron transport chain

● Transfer of excited electrons occurs between carriers in thylakoid membranes

Photon gradient

● Excited electrons from PSII are used to generate a proton gradient

Chemiosmosis

● ATP synthase in thylakoids generates ATP using the proton gradient

Reduction of NADP

● Excited electrons from PSI reduce NADP

Carbon fixation

● In the LIR, a carboxylase catalyses the carboxylation of ribulose-biphosphate

● G3P is converted into triose phosphate by

o 2 x ATP => 2 x ADP + P o 2 x reduced NADP => 2 x NADP READ OXFORD STUDY GUIDE FOR THIS ^

The fate of triose phosphate

● Triose phosphate regenerates RuBP and produces carbohydrates

RuBP regeneration

● RuBP is reformed using ATP

Chloroplast structure and function

● Structure of the chloroplast is adapted to its function in photosynthesis ● Double membrane forming outer chloroplast envelope

Chloroplasts structure-function relationship

● Contain light absorbing arrays/ photosystems/ chloroplasts