BI108 Quiz 2 Flashcards

What is energy?

The ability to do work.

What type of energy is related to the movement of charged particles?

Electrical energy.

What is thermal energy?

Energy of motion in ions and particles.

What is potential energy?

Energy related to position.

What is free energy?

Total energy available to do work, combining entropy and thermal/potential energy in the ions and molecules involved.

What do double-headed arrows in chemical reactions indicate?

The reactions can go in either direction.

What type of chemical reactions are more likely to be spontaneous?

Reactions that lead to an increase in entropy or lower potential energy.

What is ATP and its components?

ATP consists of 3 phosphate groups, a 5-carbon sugar, and a nitrogenous base adenine.

What is phosphorylation?

The process in which a phosphate group is added to a molecule.

Why is phosphorylation important in energetic coupling?

It allows proteins to change shape and increases potential energy enough to make a chemical event happen. ADP + Pi = ATP is an example of phosphorylation.

How is ATP used by cells?

ATP is critically important but not stored in large quantities and is re-used by the minute.

What is an endergonic reaction?

A non-spontaneous reaction that absorbs free energy. Products have higher potential energy than reactants.

What is an exergonic reaction?

A reaction that releases free energy. Products have lower potential energy than reactants.

What are two reasons spontaneous/exergonic reactions aren't necessarily fast without an enzyme?

1. Spatial orientation: unlikely for reactants to achieve the random yet precise orientation needed.

2. High activation energy: activation energy needed is too high and becomes a barrier for the reaction

What is activation energy?

The minimum energy required to initiate a chemical reaction by enabling reactants to reach a transition state, serving as a barrier to product formation.

How do enzymes catalyze reactions?

By binding substrates at their active sites so that reactions can occur and lowering the reaction's activation energy.

What is the role of active sites in enzymes?

Active sites are where reactants bind. The enzyme converts the reactants into products.

Do enzymes change after a reaction?

No, enzymes are the same molecule before and after the reaction.

What is the first law of thermodynamics?

Energy is neither created nor destroyed but can be converted from one form to another.

What is kinetic energy?

Energy of movement, including thermal, sound, and electromagnetic energy.

What are exergonic reactions?

Reactions that release free energy, resulting in a negative change in free energy.

What are endergonic reactions?

Reactions that consume free energy, resulting in a positive change in free energy.

What is an anabolic reaction?

A reaction where complex molecules are made from simple molecules, requiring energy input.

What is a catabolic reaction?

A reaction where complex molecules are broken down into simpler ones, releasing energy.

What is the role of kinases?

Enzymes that catalyze phosphorylation by adding or removing phosphate groups.

What is the purpose of metabolic pathways?

To convert molecules into other molecules or release energy through a series of interconnected biochemical reactions.

What are the inputs and outputs of glycolysis?

Inputs: 1 glucose, 2 ATP, 2 NAD+ + Pi

Outputs: 4 ATP, 2 NADH, 2 pyruvate

What are the inputs and outputs of pyruvate processing?

Inputs: 2 pyruvate, 2 NAD+, 2 CoA

Outputs: 2 NADH, 2CO2, 2 acetyl-CoA

What are the inputs and outputs of ATP synthesis?

Inputs: 4 H+ per ADP, ADP + Pi

Outputs: ~28 ATP

What is oxidative phosphorylation?

The combined action of the electron transport chain and ATP synthase to produce ATP.

What are electron carriers in cellular respiration?

Molecules like NADH and FADH2 that shuttle electrons to the electron transport chain.

What is the final electron acceptor in the electron transport chain?

Oxygen, which converts protons into water.

What is the role of ATP synthase?

To convert ADP and inorganic phosphate into ATP using energy from a proton gradient.

What is the difference between oxidation and reduction?

Oxidation is the loss of electrons, while reduction is the gain of electrons.

What is the significance of redox reactions in cellular respiration?

They involve the transfer of electrons, driving ATP production.

What is substrate-level phosphorylation?

A method of generating ATP by transferring a phosphate group directly to ADP from a substrate.

What is the role of allosteric regulation?

To control enzyme activity by binding molecules that change the enzyme's shape.

What is competitive inhibition?

A type of inhibition where substrates are prevented from entering the active site.

What is allosteric inhibition?

Inhibition where an inhibitor binds elsewhere on the enzyme, altering the shape of the active site.

What is the role of activators in enzyme activity?

Molecules that increase reaction rates by binding to enzymes and altering their shape to encourage substrate binding.

What is the are the inputs and outputs of the citric acid cycle?

Inputs: 2 acetyl-CoA, 6 NAD+, 2 FAD+, 2 GDP + Pi

Outputs: 6 NADH, 2 FADH2, 4 CO2, 2 GTP

What is the net ATP yield from glycolysis?

2 ATP from one molecule of glucose.

What do carbon atoms in glucose become fully oxidized to?

CO2

What is the role of NADH and FADH2 in cellular respiration?

NADH and FADH2 act as high-energy electron carriers produced during glycolysis, pyruvate oxidation, and the citric acid cycle. Their primary role is to transport these electrons to the electron transport chain (ETC).

What process directly produces ATP during glycolysis?

A small amount of ATP is created during phosphorylation.

What happens to electrons from NADH and FADH2 in the electron transport chain (ETC)?

They release H+ ions in redox reactions to create chemical energy that powers pumps across mitochondrial membranes in the proton gradient.

What gradient is created by the pumps in the ETC?

A proton gradient which also creates a concentration and charge gradient.

How is ATP synthesized from ADP during cellular respiration?

Protons flow down the concentration gradient through ATP synthase, catalyzing ATP synthesis.

What is the final electron acceptor in many organisms during cellular respiration?

Oxygen.

What occurs during fermentation in muscles due to oxygen depletion?

ETC gets backed up, NADH and FADH2 build up, and ATP production stops.

What is the adaptive value of fermentation?

It allows cells to process glucose and produce small amounts of ATP temporarily.

What is anaerobic respiration?

A process where electrons reduce substances other than oxygen.

What is the overall equation for photosynthesis?

6CO2 + 12H2O + light energy → C6H12O6 + 6O2 + 6H2O.

What are the major steps in photosynthesis?

Light reactions and the Calvin cycle.

What do pigments do in photosynthesis?

They absorb light energy and convert it to chemical energy.

What is the role of Rubisco in the Calvin cycle?

It catalyzes the first step by attaching CO2 to a 5-carbon sugar.

What happens to electrons when a photon strikes chlorophyll?

An electron gets excited, which can lead to energy release or transfer.

What is the function of ATP synthase?

It synthesizes ATP from ADP and inorganic phosphate using a proton gradient.

What is the significance of the light reactions in photosynthesis?

They convert light energy into chemical energy (ATP and NADPH).

What is the main function of oxygen in cellular respiration?

To accept electrons released by glucose oxidation.

What are the inputs and outputs of the electron transport chain?

Inputs: NADH, FADH2, O2, ADP + Pi

Outputs: NAD+, FAD+, H2O, proton gradient

What is the role of guard cells in plants?

They regulate the opening of stomata for CO2 entry.

What is the importance of the Calvin cycle?

Its primary purpose is to convert atmospheric CO2 into glucose, using the ATP and NADPH produced during the light-dependent reactions.

What is the relationship between cellular respiration and photosynthesis?

They are separate but related metabolic pathways.

What happens during the reduction phase of the Calvin cycle?

3-PGA is reduced to G3P using ATP and NADPH.

What is the final product of the Calvin cycle?

G3P, which can be used to make glucose and other compounds.

How is energy transformed during cellular respiration?

Energy is released from glucose and stored as ATP.

What are the inputs and outputs of ATP synthase?

Inputs: proton gradient, ADP, and inorganic phosphate; Outputs: ATP.

What is the role of NADPH in photosynthesis?

It acts as an electron carrier in the Calvin cycle.

What is the significance of the proton gradient in ATP synthesis?

It drives the synthesis of ATP as protons flow through ATP synthase.

What happens to carbon atoms during photosynthesis?

They are reduced to form carbohydrates in a process called carbon fixation.

What are the inputs and outputs of the ETC (light reactions)?

Inputs: photons (from light), H2O, NAP+, ADP + Pi

Outputs: O2 (and H+), NADPH, ATP, proton gradient

What are the inputs and outputs of the Calvin Cycle (non-light reactions)?

Inputs: CO2, ATP, NADPH

Outputs: G3P (makes glucose), ADP +Pi, NADP+