Lecture 6 - Respiration and photosynthesis

Explain glycolysis?

• Glucose is broken down into 2 pyruvate, 2 NADH is made as well as 2 ATP, 4 made but 2 used in process

• Takes place in cytosol

• Production of ATP is called substrate level phosphorylation

• 1 glucose (6 Carbons) Broken down into 2 pyruvate (3 carbons) in cytoplasm

Explain 2A pyruvate oxidation?

• Pyruvate is transported into mitochondria

• Produced Acetyl - CoA and CO2

• Produces 1 NADH per pyruvate, therefore 2 NADH

2B - citric acid cycle

• Acetyl CoA enters citric acid cycle

• Produced 2 CO2, 1 FDHA, 3 NDHA, 1 ATP all x2

• Start with 6c end with 4c

Explain Ox phos?

• glycosis, oxidation of pyruvate and citric acid cycle produce 4 molecules of ATP

• Energy released from glucose oxidation is trapped in NADH and FADH2

• Produces 26-28 ATP per glucose molecule

• 2 main phases, electron transport chain - energy released pump protons across membrane, chemiosis forms ATP

Explain electron transport chain?

• 4 membrane protein complexs (1-4) pass electrons along chain

• High energy electrons from NADH and FADH2 are passed between the 4 complexs

• Creates a dam of H+ ions (gradient)

• Final step in ETC, electron acceptor is oxygen which is reduced to water

• Energy is released with each electron transfer, used to pump proteins from matrix into inner membrane = proton graident

Explain chemiosis?

• Gradient of protons creates potential energy

• H+ ions cant pass through membrane so use specific carrier - ATP synthase

• ATP synthase works like a mill, protons fall, spins mill and generates kinetic energy

• ATP uses energy to make 1 ATP every 4 protons

What happens if there is no oxygen?

• No oxygen means ox phos cannot work, oxygen is finally electron acceptor

• ATP still generates by glycosis and pyruvate

• Undergo anaerobic ex phos using sulfate and nitrate

Respiration vs Photosynthesis

• Photosynthesis equation is the opposite of respiration

Explain chloroplast?

• Found in plants and algae

• 3 membrane systems, outer, inner and thylakoid

• Thylakoid contains chlorophyll - light harvest energy

What happens during photosynthesis?

• light reactions, produce energy and reduce power in thylakoid

• Dark reactions - use energy and reduce power to produce sugars, occurs in stroma

Describe electron transport and chemiosis in photosynthesis?

• Light is absorbed, water is oxidised to oxygen

• NADP+ is the electron acceptor is reduced to NADPH

• Light energy drives electron transport

• Proton gradient is formed, ATP made using ATP synthase