C1.2 Molecules and Cell Respiration Flashcards

Flashcards from lecture notes on C1.2 Molecules and Cell Respiration.

ATP (adenosine triphosphate)

A nucleotide with the base adenine, ribose, and three phosphate groups that serves as the basic energy currency in all cells.

Ideal properties of ATP as a cellular energy currency

Chemically stable at neutral pH, soluble in water, unable to diffuse through phospholipid bilayers, and able to release sufficient energy for cellular tasks.

Four examples of processes supplied with energy by ATP

Active transport, synthesis of macromolecules, movement of cell components, and movement of the whole cell

ATP and ADP interconversion

Energy is released when ATP is converted to ADP; energy is invested to convert ADP to ATP.

Conversion of ADP to ATP

A phosphorylation reaction, producing water.

Conversion of ATP to ADP

A hydrolysis reaction, requiring a water molecule to be split.

Cell respiration

The part of metabolism in which carbon compounds are oxidized to release energy in the form of ATP.

Ventilation (breathing)

Moving air in and out of the lungs.

Gas exchange

Swapping one gas for another at a surface where a cell or organism is in contact with its environment.

Aerobic Cell Respiration

Cellular respiration with the use of oxygen.

Anaerobic Cell Respiration

Cellular respiration without the use of oxygen.

Aerobic Respiration Substrates, Yield, Waste Products, and Location

Sugars or lipids and produces 30-32 ATP molecules with carbon dioxide and water as waste products with the location of the reaction occurring in the cytoplasm and mitochondria.

Anaerobic Respiration Substrates, Yield, Waste Products, and Location

Glucose and other sugars producing 2 ATP molecules with lactate as a waste product with the location of the reaction occurring only in the cytoplasm.

Respirometer

A device that measures the rate of cell respiration.

Dehydrogenation

Pairs of hydrogen atoms are removed from substrates.

NAD (nicotinamide adenine dinucleotide)

A hydrogen carrier that accepts two hydrogen atoms and is reduced.

Glycolysis

The first part of both aerobic and anaerobic respiration if glucose is the substrate, happening in the cytoplasm of all cells.

Glycolysis Step 1: Phosphorylation

Glucose is phosphorylated twice to form hexose biphosphate that requires two ATPs

Glycolysis Step 2: Lysis

Hexose biphosphate is split to form two molecules of triose phosphate.

Glycolysis Step 3: Oxidation

Two atoms of hydrogen are removed from each triose phosphate molecule, ending with pyruvate.

Glycolysis Step 4: ATP Formation

Oxidizing each triose phosphate molecule converts two ADP molecules to ATP.

Regenerating NAD in anaerobic cell respiration in humans

In human cells NAD is regenerated by transferring hydrogen atoms from reduced NAD to pyruvate, oxidizing the reduced NAD to NAD and reducing the pyruvate to lactate.

Regenerating NAD in anaerobic cell respiration in yeast

Yeast converts pyruvate to ethanal by removing CO2; the ethanal is then reduced to ethanol by transferring two hydrogen atoms from reduced NAD, producing NAD.

Link reaction

Conversion of pyruvate produced by glycolysis into acetyl groups needed for the Krebs cycle.

Changes to Pyruvate during the Link Reaction

Carbon dioxide is removed, and a pair of hydrogen atoms is removed. An acetyl group remains, which is linked to a carrier molecule called CoA (Coenzyme A), to produce acetyl-CoA.

Krebs Cycle

Acetyl groups are fed into the Krebs cycle by transfer from acetyl CoA to a four-carbon organic acid (oxaloacetate), producing a six-carbon organic acid (citrate).

Three Types of Reactions during Krebs Cycle

Carbon dioxide is removed in two decarboxylation reactions; hydrogen is removed in four reactions; ATP is produced directly in one of the reactions using substrate-level phosphorylation.

Electron transport chain

A series of carriers, located in the inner membrane of the mitochondrion.

Generating a proton gradient

The electron carriers act as proton pumps and use the energy released by electron flow to pump protons (H+) from the matrix of the mitochondrion to the intermembrane space.

Chemiosmosis

The coupling of the energy-releasing process of electron transport to the energy-requiring process of ATP production.

ATP Synthase Rotor

ATP synthase has binding sites on the sides of the rotor that allow protons from the intermembrane space to bind to these sites, but they can only be released into the matrix when the rotor is in a different position, achieved by rotation.

Oxygen as the terminal electron acceptor

The last carrier passes the electrons, now depleted of energy, to oxygen, which also accepts protons (H+) from the matrix, to form water.

Lipids (triglycerides) as a respiratory substrate

Has a C:H:O ratio of 1:2:0.065, releases 37 kJ per gram, and is used only for aerobic respiration.

Carbohydrates as a respiratory substrate

Has a C:H:O ratio of 1:2:1, releases 16 kJ per gram, and is used for aerobic or anaerobic respiration.