Cell Functions - AP Biology

The "S" phase, known as the synthesis phase, is the portion of the cell cycle where DNA is replicated. The other stages listed do not contain DNA replication. G0 is a cell cycle arrest phase, where a cell remains dormant, awaiting signals to re-enter the cell cycle.

All these events occur in prophase, the first stage of mitosis. Metaphase involves the duplicated chromosomes being aligned along the metaphase plate, with each pair of sister chromatids attached to spindle fibers. During anaphase, the sister chromatids are pulled apart to opposite poles of the cell. Telophase is essentially the opposite of prophase: the DNA decondenses, the nuclear envelope begins to reform, and the mitotic spindle begins to disappear.

In the absence of oxygen, pyruvate produced during glycolysis will be used for either lactic acid or alcoholic fermentation, producing lactic acid or ethanol (as waste products) and regenerating NAD+ to be used for another cycle of glycolysis. This fermentation occurs in the cytosol of the cell.

Pyruvate decarboxylation is an oxidative decarboxylation reaction, or an oxidation reaction where a carboxylate group is removed. This reaction converts pyruvate which was produced through glycolysis to acetyl CoA to be used in the Citric Acid Cycle.

The pyruvate dehydrogenase complex is an enzyme complex that consists of 3 enzymes, which work together to catalyze the pyruvate decarboxylation reaction, where pyruvate is converted to acetyl CoA.

Pyruvate decarboxylation occurs in the mitochondrial matrix. The acetyl CoA produced from the pyruvate decarboxylation reaction will undergo the Citric Acid cycle also in the mitochondrial matrix.

During glycolysis, for each molecule of glucose, two molecules of pyruvate are produced ( glucose+ NAD+ + 2 ADP + 2Pi-> 2 pyruvate+ 2 ATP + 2NADH+. These 2 molecules of pyruvate then undergo the pyruvate decarboxylation reaction: 2(pyruvate+ CoA-SH+ NAD+ -> NADH+ CO2+ acetyl CoA).

The pyruvate decarboxylation reaction is pyruvate+ CoA-SH+ NAD+ -> NADH+ CO2+ acetyl CoA.

During the pyruvate decarboxylation reaction , a thioester bond links the acetyl group of pyruvate with coenzyme A to produce acetyl CoA.

Glycolysis happens in the cytosol (the fluid containing the organelles) of the cell. The next step in cellular respiration, the citric acid cycle, occurs in the mitochondria.

NAD+ is required as an oxidizing agent (accepting electrons from other molecules) during glycolysis. As it accepts electrons, it becomes NADH, a byproduct of glycolysis. NADH can be reverted back to NAD+ to continue glycolysis through the process of fermentation, but is usually used to donate the added electron to the electron transport chain later in the cell metabolism process. The electron is used to power the protein pumps that create the proton gradient that powers ATP synthase.

Glycolysis is the first step of cellular respiration and, in the process of splitting glucose into two pyruvate molecules, does not require oxygen.

Pyruvate decarboxylation, the citric acid cycle, and oxidative phosphorylation are all steps in aerobic respiration, and thus require the presence of oxygen.

Fermentation oxidizes molecules of NADH to NAD+ so the cell can have oxidizing agents for any subsequent glycolysis reactions. It does not, however, produce any usable energy in the process.

Fermentation leads to the production of ethanol in yeast cells and lactic acid in muscle cells.

Glycolysis occurs in the cytosol of cells. Once finished, the two pyruvate products are transported into the mitochondria to go through the citric acid cycle, at a cost of 1 ATP per pyruvate. Neither the nucleus, nor the endoplasmic reticulum have any function in glycolysis or the citric acid cycle.

The conversion of glucose to two pyruvate molecules in glycolysis produces a net total of two direct ATP. When fructose-1,6-bisphosphate enters glycolysis, it bypasses the two steps involved that normally cost one ATP each, therefore, there is no required input and the net total is four produced ATP.

We have to remember that each step beyond the conversion of fructose-1,6-bisphosphate to glyceraldehyde-3-phosphate and dihydroxyacetone phosphate happens twice, or we would come up with two ATP created.

Glycolysis is the first step in cellular respiration, and is seen in both aerobic and anaerobic respiration. The products of glycolysis are pyruvate, NADH, ATP, and water. Oxygen is only a product of the light reactions of photosynthesis; it is consumed as a reactant in the electron transport chain.

Fructose-2,6-bisphosphatase is an enzyme that is responsible for regulating glycolysis and gluconeogenesis. When serine-32 is phosphorylated on fructose-2,6-bisphosphatase, glycolysis is stimulated and gluconeogenesis is inhibited.

Glycolysis produces two molecules of pyruvate and two molecules of NADH. The cell technically produces four molecules of ATP during glycolysis; however, it uses two molecules to initiate the process. The net production of ATP is only two. FADH2 is produced in the Krebs cycle.

The correct answer to this question is glycolysis.

We can know this if we remember that glycolysis is a ten step anaerobic, not aerobic pathway that uses the 6 carbon sugar known as glucose and converts it to 2 pyruvate molecules. All of the other answers do not use glucose and convert it to pyruvate.