AP Biology Topic 3: Cellular Energetics

Enzymes

Proteins that are biological catalysts that speed up chemical reactions by lowering activation energy.

What is the shape of most enzymes?

Most enzymes have a unique three-dimensional shape that is essential for their specific function and interactions with substrates.

Substrate

The specific reactant molecule that an enzyme acts on during a chemical reaction.

Active Site

The specific region on an enzyme where substrates bind and undergo a chemical reaction. This area is crucial for the enzyme's catalytic activity.

How can enzyme be compatible with its substrate?

Activation Energy

The minimum energy required for a chemical reaction to occur, often lowered by enzymes to increase reaction rates.

Control Group

Experimental Group

How does temperature affect enzyme shape?

Changes in enzyme activity and function.

How does a high temperature impact enzymes?

At high temperatures, enzymes can denature, losing their specific shape and function.

How does a low temperature impact enzymes?

At low temperatures, enzyme activity decreases as molecular movement slows down, potentially reducing reaction rates.

How does pH affect enzyme shape?

Changes in enzyme activity and shape due to alterations in hydrogen ion concentration.

What happens when an enzyme is out of its optimum pH range?

Enzyme activity declines and may lead to denaturation, affecting its shape and function.

Substrate Concentration

Higher substrate concentrations can increase reaction rates until a saturation point is reached, beyond which enzyme activity plateaus.

Enzyme Concentration

An increase in enzyme concentration generally leads to a higher reaction rate, assuming substrate availability, as there are more active sites available for substrate binding.

Competitive Inhibitors

Substances that resemble the substrate and compete for the active site on enzymes, reducing the rate of enzyme activity.

Noncompetitive Inhibitors

Substances that bind to an enzyme at the allosteric site, causing a decrease in enzyme activity without competing with the substrate.

What is the main energy input of living organisms?

The main energy input of living organisms is sunlight, which is harnessed by plants during photosynthesis to produce glucose and oxygen.

What is the purpose of photosynthesis?

The purpose of photosynthesis is to convert sunlight into chemical energy in the form of glucose, while also producing oxygen as a byproduct.

How does cyanobacteria contribute to photosynthesis?

Cyanobacteria contribute to photosynthesis by using sunlight to convert carbon dioxide and water into glucose and oxygen, it is responsible for the oxygen production in the atmosphere.

What is the purpose of Light Dependent Reaction

To capture light energy by using chlorophyll and convert it into chemical energy, producing ATP and NADPH in the process.

How is oxygen produced?

Oxygen is produced as a result of hydrolysis, where water is split into oxygen.

Reactants of Light Dependent Reaction

• Light

• H2O

• ADP + P

• NADP+

Products of Light Dependent Reaction

• ATP

• NADPH

• O2

Function of chlorophylls?

Chlorophylls function primarily to absorb light energy for photosynthesis, converting it to high-energy electrons

What do the high-energy electrons produced from chlorophyll do?

They will be energized and be used to establish a prton gradient and reduce NADP+ to NADPH.

Photosystem I and II

Both are protein-pigment complexes in chloroplasts that play crucial roles in the light-dependent reactions of photosynthesis, with Photosystem I primarily producing NADPH and Photosystem II generating ATP and oxygen.

Proton Gradient

A difference in proton concentration (H+ ions) across a membrane that is used to drive ATP synthesis during photosynthesis.

What form of passive transport does photosynthesis use?

Diffusion through stomata

ATP Synthase

An enzyme that utilizes the proton gradient created by the electron transport chain to convert ADP + P into ATP during photosynthesis.

What is the purpose of the Calvin Cycle?

Uses ATP and NADPH produced in the light-dependent reactions to convert carbon dioxide into glucose.

Where does Calvin Cycle occur?

The Calvin Cycle occurs in the stroma of chloroplasts, where it uses ATP and NADPH to convert carbon dioxide into glucose.

How do organisms gain their carbon dioxide?

Organisms gain carbon dioxide primarily through the process of respiration or via diffusion from the atmosphere, which is crucial for photosynthesis in plants.

Reactants of Calvin Cycle

• ATP

• NADPH

• CO2

Products of Calvin Cycle

• Glucose

• ADP + P

• NADP+

What is the purpose of cellular respiration?

To convert biochemical energy from nutrients into adenosine triphosphate (ATP) and release waste products, primarily carbon dioxide and water.

Why is ATP so relevant in cellular respiration?

ATP is essential as it acts as the primary energy currency of the cell, providing the energy needed for various biochemical processes during cellular respiration.

What is the purpose of glycolysis?

The purpose of glycolysis is to break down one molecule of glucose into two molecules of pyruvate, producing a net gain of two ATP and two NADH in the process.

Where does glycolysis occur?

Glycolysis occurs in the cytoplasm of the cell, where glucose is broken down in a series of enzymatic reactions.

What is anaerobic reaction and why is glycolysis an example of it?

An anaerobic reaction is a metabolic process that occurs in the absence of oxygen. Glycolysis is an example because it can happen in both aerobic and anaerobic conditions, generating ATP without requiring oxygen.

Fermentation

Fermentation is a metabolic process that converts sugars to acids, gases, or alcohol in the absence of oxygen, allowing cells to generate ATP when oxygen is scarce.

Lactic Acid

Ethanol

What is the purpose of the Kreb Cycle?

The Krebs Cycle, also known as the citric acid cycle, generates energy through the oxidation of acetyl-CoA, producing NADH and FADH2 for use in the electron transport chain, while also releasing carbon dioxide as a byproduct.

Where does the Kreb Cycle occur?

The Krebs Cycle occurs in the mitochondria of eukaryotic cells. It takes place in the mitochondrial matrix, where it plays a crucial role in cellular respiration.

Reactants of Kreb Cycle

• 2 pyruvate

• O2

• ADP + P

• 2 FAD

• 8NAD+

Products of Kreb Cycle

• 2 ATP

• CO2

• 2 FADH2

• 8 NADH

What is the purpose of oxidative phosphorylation?

The purpose of oxidative phosphorylation is to generate ATP by using energy derived from electron transport and proton gradients formed during the oxidation of nutrients.

What is the final receptor?

The final electron acceptor in the electron transport chain is oxygen, which combines with electrons and protons to form water.

Reactants of Oxidative Phosphorylation

• O2

• ADP + P

• 2FADH2

• 8NAD+

Products of Oxidative Phosphorylation

• 2 ATP

• CO2

• 2FADH2

• 8NADH