Energy Systems 1

Glucose (or glycogen) is converted to two of this molecule via glycolysis

• Lactate

• Pyruvate

• Acetyl-CoA

• Hydrogen

Answer explanation

The breakdown of glucose or glycogen via glycolysis results in two pyruvate. Whether pyruvate enters the mitochondria or is converted to lactate depends on the relative activity of glycolytic enzymes, which is related to whether the three conditions are satisfied for oxidative phosphorylation.

The following molecules are stored in the body and can provide energy via high-energy phosphate bonds (one-step reaction), which can provide around 8-12 seconds of maximal intensity exercise

• ATP and Phosphocreatine

• Lipids and Glucose

• Glucose and Amino Acids

• None of the above

Answer explanation

Stored ATP and Phosphocreatine are available within the muscle and can be broken down via a one-step reaction to release energy for biologic work immediately. Utilizing these sources of energy are particularly important for sports that require powerful bursts of energy (olympic lifting, 100-m sprinting).

Fast glycolysis results the conversion of pyruvate to which molecule?

• Acetyl-CoA

• Lactate

• NADH

• Glucose

Answer explanation

Lactate forms from pyruvate in a reversible reaction, catalyzed by lactate dehydrogenase, when NADH oxidation does not keep pace with its formation in glycolysis

NADH and FADH2 are the reduced form of the coenzymes NAD+ and FAD that carry hydrogens (i.e., electrons) to this process that occurs in the mitochondria:

• Glycolysis

• Creatine Kinase reaction

• Tricarboxylic acid cycle (i.e., citric acid cycle)

• Electron transport chain

Tags

NGSS.HS-LS1-7

ATP is formed in glycolysis via:

• Substrate-level phosphorylation

• The formation of phosphocreatine

• Indirectly through the NADH + H that can be shuttled to the electron transport chain

• Two are correct

Answer explanation

ATP forms by combining ADP with inorganic phosphate at steps 7 and 10 via substrate-level phosphorylation. NADH + H is also formed during step 6 of glycolysis where ATP can be formed when the hydrogens (electrons) are shuttled down the electron transport chain.

Tags

NGSS.HS-LS1-7

What is the rate-limiting enzyme for glycolysis?

• Aldolase

• Phosphofructokinase

• Lactate dehydrogenase

• Phosphoglyceromutase

Answer explanation

The activity level of the enzyme phosphofructokinase, the enzyme that catalyzes the reaction fructose-6-phosphate to form fructose 1,6-diphosphate, limits the rate of glycolysis during maximal intensity exercise.

Where does the process of glycolysis take place in the cell?

• Cytosol

• Mitochondria

• Golgi apparatus

• Ribosome

Tags

NGSS.HS-LS2-5

This is the name for the process that describes how ATP forms during electron transfer from NADH and FADH2, with eventual involvement in molecular oxygen

• Substrate-level phosphorylation

• Glycolysis

• Tricarboxylic acid cycle (i.e., citric acid cycle)

• Oxidative phosphorylation

Answer explanation

Molecular oxygen is the final electron acceptor in the electron transport chain, which is why the process is called oxidative phosphorylation.

Tags

NGSS.HS-LS1-7

Performing a 400-m sprint (~70-90 sec) would primarily rely on ATP resynthesis from which of the following processes?

• Stored ATP and phosphocreatine

• Fast glycolysis

• Oxidative phosphorylation

• None of the above

Answer explanation

Glycolysis in which pyruvate converts to lactate can provide ATP rapidly for maximal-intensity exercise to continue for about 90 seconds. If exercise continues, ATP must be synthesized via other pathways which will result in the lowering of the pace/intensity as lactate accumulates and fatigue sets in.

The formation of pyruvate to lactate in rapid glycolysis allows for the "freeing up" of NAD+ so that rapid glycolysis can continue

• True

• False

Tags

NGSS.HS-LS2-3