Lecture 7 - The Squiggle

What percentage of cellular ATP comes from aerobic metabolism, and how much ATP can it produce per glucose?

80-90%, 28-38 atp per glucose

How do bacterial flagella use proton movement?

proton movement powers rotation

How does ATP synthase use proton movement?

energy from proton movement to produce atp

What does bacterial rhodopsin demonstrate?

link between proton pumping and atp synthesis

What are the two components of the proton motive force (PMF)?

chemical gradient, electrical gradient

How is the PMF generated?

electron transport provides energy to move h across membrane

How does the PMF help produce ATP?

h flows down its electrochemical gradient through atp synthase, providing energy for atp production

Where are ATP synthases located in mitochondria?

inner mitochondrial membrane along cristae ridges

How can ATP synthases be organised on cristae?

form dimers

What is the function of the stator?

holds catalytic region in place

What is the function of the rotor?

c subunits bind protons and rotate

What is the function of the internal rod?

rotates and interacts with catalytic region, changing shape

How many ATP are produced per full rotation of ATP synthase?

three, because three catalytic sites

What reaction does ATP synthase catalyse?

adp + pi = atp

What are the two shuttles that transfer electrons from glycolytic NADH?

malate asparate shuttle, g3pdh shuttle

How does the malate-aspartate shuttle work?

electrons transferred to malate, crosses membrane via transporter, electrons transferred to nad to produce nadh

How much ATP does the malate-aspartate shuttle yield per glycolytic NADH?

2.5 atp

What are the main characteristics of the malate-aspartate shuttle?

slow but more efficient

How does the G3PDH shuttle differ from the malate-aspartate shuttle?

trasnfers electrons through a pathway involving fad

How much ATP does the G3PDH shuttle yield per glycolytic NADH?

1.5 atp

What are the main characteristics of the G3PDH shuttle?

faster but less efficient, some energy released as heat

How much ATP is produced per NADH and FADH₂?

nadh 2.5, fadh2 1.5

Why does ATP yield vary?

high temperature can make membranes leaky, different efficiencies of shuttles, h used for other cell processes

How can a mutation in the ATP synthase C-ring affect ATP production?

proton slippage, reducing efficiency

What can happen if Complex I is impaired?

electron transport and atp production decrease

What conditions are associated with mitochondrial membrane damage in the lecture?

aging, oxidative stress and diabetes

What is uncoupling and the function of UCP1?

allows h to cross membrane without using atp synthase, energy released as heat

What is DNP, and why is it dangerous?

chemical uncoupler that disrupts pmf, causes dangerous overheating