Cell Energy 1

Relationship between respiration, breathing, and cellular respiration

Breathing (respiration) takes in oxygen and releases carbon dioxide through the lungs, while cellular respiration is the intracellular chemical process that uses oxygen to harvest energy from food molecules (glucose) and produces carbon dioxide as waste

Gas exchange in Section 6.2 and involved body parts

Oxygen is taken in and carbon dioxide is expelled, handled externally by the lungs and circulatory system and internally by mitochondria inside individual cells

Efficiency of cellular respiration vs. car gas combustion

Cellular respiration captures roughly 34% to 40% of food energy as ATP, whereas car engines convert only about 20% to 25% of gasoline energy into mechanical work

Where does the rest of cellular respiration energy go?

The remaining ~60% to 66% of energy is released as heat to warm the organism

Daily ATP usage by the human body

The body uses and recycles approximately 10^28 ATP molecules (roughly equivalent to your entire body weight in ATP) each day

Daily energy (kcal) needed for basic functions vs. voluntary activity

The human body uses roughly 2,000 to 2,200 kcal daily total (~1,300–1,500 kcal for basic resting functions plus additional energy for physical activity)

Definition of a kilocalorie (kcal)

A kilocalorie is 1,000 calories; it is the amount of heat energy required to raise the temperature of 1 kg of water by 1°C

Energy content per gram: Proteins, Carbohydrates, and Lipids

Proteins: ~4 kcal/g; Carbohydrates: ~4 kcal/g; Lipids (fats): ~9 kcal/g

How Rotenone affects oxidative phosphorylation

Binds to Complex I of the electron transport chain, blocking electron flow from NADH and preventing the proton gradient needed for ATP synthesis

How Carbon Monoxide and Cyanide affect oxidative phosphorylation

Both bind to Complex IV (cytochrome c oxidase) at the end of the electron transport chain, blocking electrons from binding to oxygen and halting ATP production

How Oligomycin affects oxidative phosphorylation

Directly inhibits ATP synthase by blocking its proton channel, stopping protons from flowing back into the matrix to make ATP

Cellular respiration adaptation in hibernating mammals and newborns

Brown adipose tissue (brown fat) contains uncoupling proteins (thermogenin) that let protons leak across the inner mitochondrial membrane to generate heat instead of ATP

Mechanism and effects of 2,4-Dinitrophenol (DNP)

Acts as a proton ionophore uncoupler, carrying protons across the inner mitochondrial membrane and bypassing ATP synthase, causing the ETC to run frantically and release all energy as heat

Why DNP was banned in 1938 and why people still take it today

Banned due to severe toxicity, hyperthermia, and organ failure; still taken illicitly today by some individuals for rapid fat loss