Campbell Biology: Concepts & Connections - Cellular Respiration

Flashcards on cellular respiration processes, stages, and related concepts.

Cellular Respiration

Breaks down sugar and other food molecules and generates ATP, the energy currency in cells, and heat.

Brown fat cells

Cells that have a “short circuit” in their cellular respiration, which generates only heat, not ATP.

Photosynthesis

The energy of sunlight is used to rearrange the atoms of carbon dioxide (CO2) and water (H20), producing organic molecules, and releasing oxygen (O2).

Cellular respiration

O2 is consumed as organic molecules are broken down to CO2 and H2O and the cell captures the energy released as ATP.

Respiration (breathing)

An exchange of gases where an organism obtains O2 from its environment and releases CO2 as a waste product.

Cellular respiration

An exergonic (energy-releasing) process that transfers energy from glucose to form ATP and captures about 34% of the available energy originally stored in glucose with the rest of the energy lost as heat.

Basal Metabolic Rate (BMR)

The energy requirement for basic body maintenance.

Oxidation

Loss of electrons (in atoms).

Reduction

Addition of electrons.

Dehydrogenase

Enzyme that removes electrons (in H atoms) from fuel molecules (oxidation).

NAD+

Coenzyme that accepts electrons and is converted to NADH (reduction).

Substrate Level Phosphorylation (SLP)

Simplest way to make ATP, requires no membrane, and uses a large enzyme (Kinase).

Chemiosmosis

Aerobic Respiration (mitochondria), requiring a “Proton gradient” to be generated.

Glycolysis

Occurs in the cytosol, begins cellular respiration, and breaks down glucose into two molecules of a three-carbon compound called pyruvate.

Pyruvate oxidation and the citric acid cycle

Take place in mitochondria, complete the breakdown of glucose to carbon dioxide, and supply the third stage of respiration with electrons.

Oxidative Phosphorylation

Makes the most ATP; NADH and FADH2 shuttle electrons to transport chains in inner membrane of mitochondria and involves chemiosmosis.

Glycolysis

Splits sugar molecules in the cytoplasm, starting with a single 6-carbon molecule of glucose and ending with two 3-carbon molecules of pyruvate, and produces two molecules of ATP (net production) in the process.

Substrate-level phosphorylation

An enzyme transfers a phosphate group from an organic molecule to ADP to produce a small amount of ATP.

Pyruvate oxidation

Each pyruvic acid molecule is broken down to form CO2 and a two-carbon acetyl group, which enters the Krebs cycle.

Krebs Cycle

Takes place in the mitochondria (in matrix), completes the breakdown of glucose, producing CO2 and a small amount of ATP, and supplies the third stage of cellular respiration with electrons.

Oxidative phosphorylation

Occurs in the mitochondria (inner membrane; cristae) and uses the energy released by electrons “falling” down the electron transport chain to pump H+ across a membrane.

Chemiosmosis

Harnesses the energy of the H+ gradient through chemiosmosis, producing ATP (ATP synthase).

Electron transport chain

In mitochondria, electrons from NADH and FADH2 are passed down the electron transport chain to O2, which picks up H+ to form water.

Chemiosmosis

The diffusion of ions across a membrane where build up of proton gradient just so H+ could flow through ATP synthase enzyme to build ATP.

Rotenone, cyanide, and carbon monoxide

Block parts of the electron transport chain.

Uncouplers (e.g., DNP)

Destroy the H+ gradient by making the membrane leaky to H+.

Oligomycin

Blocks the passage of H+ through ATP synthase.

Mitochondria in brown fat

Can burn fuel (burns calories) and produce heat without making ATP.

Fermentation

Is a way of harvesting energy that does not require oxygen.

Fermentation

NAD+ is recycled from NADH as pyruvate is reduced to lactate (lactic acid fermentation) or alcohol and CO2 (alcohol fermentation).

Strict anaerobes (obligate anaerobes)

Require anaerobic conditions to generate ATP by fermentation and are poisoned by oxygen.

Facultative anaerobes

Can make ATP by fermentation OR oxidative phosphorylation depending on whether O2 is available.

Glycolysis

Occurs in the cytosol of the cells of all organisms and is thought to have evolved in ancient prokaryotes.