Enzyme Action and ATP Synthesis

Flashcards covering cellular metabolism, enzyme kinetics, dehydration synthesis, hydrolysis, and the stages of cellular respiration.

What is cellular metabolism?

Cellular Metabolism is the group of chemical reactions that acquire, store, and release energy in the cells of the body.

How do anabolic and catabolic reactions differ in function and energy usage?

Anabolic reactions build larger molecules from smaller ones and require energy, whereas catabolic reactions break down larger molecules into smaller ones, releasing energy ($40\%$) and heat ($60\%$).

What chemical process occurs during dehydration synthesis?

A hydrogen ($H$) atom is removed from one molecule and a hydroxyl ($OH$) group is removed from another ($H + OH \rightarrow H_2O$), joining two smaller molecules together and releasing a water molecule.

What molecules combine via dehydration synthesis to form a triglyceride?

1 glycerol molecule and 3 fatty acid molecules bind together, producing 1 triglyceride molecule and 3 water ($H_2O$) molecules.

What is the specific name of the bond that joins two amino acids together?

A peptide bond.

How does the process of hydrolysis break down larger molecules?

A molecule of water ($H_2O$) is split and its parts are inserted into a larger molecule to break its chemical bonds.

What are the products when sucrose undergoes hydrolysis?

Glucose and fructose ($\text{Sucrose} + H_2O \rightarrow \text{Glucose} + \text{Fructose}$).

How do enzymes act as catalysts to speed up chemical reactions?

Enzymes lower the activation energy (the start-up energy) required for a reaction to occur without being consumed in the process.

What is the active site of an enzyme?

The specific 3D region on an enzyme where the substrate attaches to form an enzyme–substrate complex.

What role does a rate-limiting enzyme play in a metabolic pathway?

It acts as the main control point in a pathway, usually at the first step, and dictates the speed of the entire sequence of reactions.

What are the two types of enzyme cofactors described in the text?

Inorganic ions (such as calcium, iron, or zinc) and small organic molecules called coenzymes (many of which are derived from vitamins).

Which environmental factors can irreversibly denature enzyme proteins?

High heat, extreme pH, chemicals, radiation, electricity, extreme cold, and poisons.

How is energy released from nutrient breakdown allocated in the cell?

Approximately $40\%$ of the released energy is captured and stored in ATP, while the remaining $60\%$ is released as heat.

What structural change occurs to ATP when it releases energy for cellular work?

ATP loses one of its three phosphate groups, converting into ADP (Adenosine Diphosphate).

What are the chemical reactants and final products of cellular respiration?

The reactants are glucose ($C_6H_{12}O_6$) and oxygen ($O_2$), and the final products are carbon dioxide ($CO_2$), water ($H_2O$), and ATP.

Where in the cell does glycolysis take place, and does it require oxygen?

Glycolysis takes place in the cytosol and is an anaerobic process (does not require oxygen).

What are the net products of glycolysis from one 6-carbon glucose molecule?

2 pyruvic acid ($3\text{-C}$) molecules, 2 net ATP, and high-energy electrons carried by NADH.

What happens to pyruvic acid in human cells during anaerobic conditions?

Pyruvic acid undergoes lactic acid fermentation and is converted into lactic acid.

What transformation does pyruvic acid undergo before entering the citric acid cycle?

It enters the mitochondria, loses one carbon atom as carbon dioxide ($CO_2$), and forms acetyl CoA.

What are the main outputs of the Citric Acid Cycle (Krebs Cycle)?

$CO_2$ (waste gas), 2 ATP, and high-energy electrons carried by NADH and $FADH_2$.

What is the final electron acceptor in the Electron Transport Chain, and what is produced?

Oxygen is the final electron acceptor, which combines with hydrogen to form water ($H_2O$).

What is the ATP yield per stage and the total ATP produced from one glucose molecule in aerobic respiration?

Glycolysis yields 2 ATP, the Citric Acid Cycle yields 2 ATP, and the Electron Transport Chain yields ~28 ATP, producing a total of approximately ~32 ATP.