Enzymes and Metabolic Pathways

Flashcards covering key concepts in enzymes, photosynthesis, and cellular respiration.

What are enzymes and their role in chemical reactions?

Enzymes are catalysts that speed up chemical reactions necessary to support life.

What is the significance of the active site of an enzyme?

The active site is where the enzyme interacts with the substrate; their shapes must fit for the reaction to occur.

What happens to an enzyme's catalytic function when it undergoes denaturation?

Denaturation changes an enzyme’s structure, limiting its ability to catalyze reactions, though it can potentially be reversed.

What are competitive inhibitors and how do they affect enzyme function?

Competitive inhibitors compete with substrates for the active site, reducing the rate of enzyme-catalyzed reactions.

How can the effect of competitive inhibitors be overcome?

The effects can be diluted by increasing the concentration of the substrate.

What distinguishes noncompetitive (allosteric) inhibitors from competitive inhibitors?

Noncompetitive inhibitors bind to an allosteric site, changing the enzyme's shape and function without competing for the active site.

What are cofactors and coenzymes and their role in enzyme activity?

Cofactors are inorganic molecules, and coenzymes are organic molecules that increase the efficiency of enzyme-catalyzed reactions.

What is activation energy (Ea) in the context of chemical reactions?

Activation energy is the energy required to reach the transition state and begin a reaction.

How do enzymes lower activation energy? Name one method.

Enzymes lower activation energy by bringing substrates together in the optimal orientation for a reaction.

What is the 1st law of thermodynamics?

Energy cannot be created or destroyed, only transformed.

What is the significance of the 2nd law of thermodynamics in biological systems?

It states that disorder (entropy) within a system increases with each energy transformation, necessitating a constant energy input in living organisms.

What is photosynthesis and its overall chemical equation?

Photosynthesis is the process by which autotrophs convert light energy into chemical energy, with the equation: $6CO_2 + 6H_2O ightarrow C_6H_{12}O_6 + 6O_2$.

What are the two main stages of photosynthesis?

The two main stages are light-dependent reactions and light-independent reactions (Calvin cycle).

What occurs during the light-dependent reactions of photosynthesis?

Light-dependent reactions use photons to split water, producing ATP and NADPH.

What is the Calvin cycle?

The Calvin cycle utilizes ATP, NADPH, and CO2 to produce sugars.

What is glycolysis and its main outputs?

Glycolysis is the process where glucose is broken down into two 3-carbon pyruvate molecules, producing a net gain of 2 ATP and 2 NADH.

What processes are included in cellular respiration?

Cellular respiration includes glycolysis, oxidation of pyruvate, the Krebs cycle, and oxidative phosphorylation.

What occurs during the Krebs cycle?

The Krebs cycle involves the oxidation of acetyl groups to release CO2, generating NADH, FADH2, and ATP.

What is oxidative phosphorylation?

Oxidative phosphorylation is the process where ATP is generated using the ETC and chemiosmosis.

What are the two types of fermentation and how do they differ?

Alcohol fermentation converts pyruvate to alcohol and CO2, while lactic acid fermentation converts pyruvate to lactic acid without producing CO2.