Cellular Respiration Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary role of NADH and FADH2 in the electron transport chain?

They donate electrons to the electron transport chain. (correct)

They are responsible for the production of GTP.

They form water when combined with oxygen.

They directly synthesize ATP from ADP.

Which component of the electron transport chain is responsible for passing electrons to O2?

NADH

Cytochromes (correct)

FADH2

ATP Synthase

What is the primary role of glycolysis in cellular respiration?

To completely oxidize glucose to CO2

To produce oxygen

To break down glucose into pyruvate (correct)

To synthesize glucose from pyruvate

What is the outcome when electrons are transported through the electron transport chain?

Reduction of oxygen to form water. Signup and view all the answers

How many molecules of ATP are generated during glycolysis per molecule of glucose?

2 Signup and view all the answers

What is one significant feature of the electron transport chain?

It involves a series of multiprotein complexes. Signup and view all the answers

What happens during the energy investment phase of glycolysis?

ATP is consumed to phosphorylate glucose Signup and view all the answers

Which statement accurately describes the free energy of electrons in the electron transport chain?

Electrons drop in free energy progressively down the chain. Signup and view all the answers

What is the fate of pyruvate in the absence of oxygen?

It undergoes fermentation Signup and view all the answers

What is the role of the reducing agent in a redox reaction?

It donates electrons and becomes oxidized. Signup and view all the answers

In glycolysis, which molecule serves as the electron carrier?

NAD+ Signup and view all the answers

During cellular respiration, which substance is oxidized?

Glucose Signup and view all the answers

Which of the following describes reduction in a redox reaction?

A substance gains electrons. Signup and view all the answers

What analogy is used to describe glucose and ATP in cellular respiration?

Glucose is like a larger-denomination bill, and ATP is like smaller-denomination bills. Signup and view all the answers

What is the main product of glycolysis?

Pyruvate Signup and view all the answers

Which statement is true about some redox reactions?

They may change electron sharing in covalent bonds. Signup and view all the answers

What happens to energy during the oxidation of organic fuel molecules?

It is released as electrons are transferred. Signup and view all the answers

Which phase of glycolysis results in the formation of NADH?

Energy payoff phase Signup and view all the answers

Which statement accurately describes the occurrence of glycolysis?

It can occur with or without oxygen. Signup and view all the answers

Which of the following represents an example of an oxidizing agent?

Oxygen Signup and view all the answers

In the reaction between methane and O2, which change occurs?

Oxygen undergoes reduction. Signup and view all the answers

What is the role of phosphoenolpyruvate (PEP) in glycolysis?

It acts as a substrate for pyruvate kinase. Signup and view all the answers

Which reaction occurs during the conversion of pyruvate to acetyl CoA?

Reduction of NAD+ to NADH. Signup and view all the answers

What is directly produced from glycolysis during the energy payoff phase?

ATP Signup and view all the answers

What is the significance of converting pyruvate into acetyl CoA?

It links glycolysis with the citric acid cycle. Signup and view all the answers

Which enzyme is involved in the synthesis of phosphoenolpyruvate (PEP) from 2-phosphoglycerate?

Enolase Signup and view all the answers

What byproduct is released during the conversion of pyruvate to acetyl CoA?

CO2 Signup and view all the answers

In which cellular structure does the oxidation of pyruvate occur?

Mitochondrion Signup and view all the answers

Which of the following best describes the process that links glycolysis to the citric acid cycle?

Conversion of pyruvate to acetyl CoA Signup and view all the answers

What is the main purpose of the energy payoff phase in glycolysis?

To produce energy in the form of ATP Signup and view all the answers

In glycolysis, how many molecules of ATP are directly generated?

2 per glucose molecule Signup and view all the answers

Which enzyme catalyzes the conversion of glucose to glucose 6-phosphate in glycolysis?

Hexokinase Signup and view all the answers

During the energy investment phase of glycolysis, which of the following molecules is produced directly from fructose 6-phosphate?

Fructose 1,6-bisphosphate Signup and view all the answers

Which step of glycolysis involves the interconversion of fructose 6-phosphate and fructose 1,6-bisphosphate?

The third step Signup and view all the answers

What is the primary role of the ATP molecule in the energy investment phase of glycolysis?

To phosphorylate glucose Signup and view all the answers

Which compound is formed by the action of aldolase in the glycolytic pathway?

Glyceraldehyde 3-phosphate Signup and view all the answers

Which of the following best describes the product of the first step in glycolysis?

It is a phosphorylated form of glucose. Signup and view all the answers

During which phase of glycolysis is there a net consumption of ATP?

Energy investment phase Signup and view all the answers

What is the significance of the interconversion between glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP)?

It allows reversible reactions in glycolysis. Signup and view all the answers

The enzyme responsible for the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate is known as what?

Phosphofructokinase Signup and view all the answers

Which of the following statements about the energy investment phase of glycolysis is correct?

It requires an input of energy. Signup and view all the answers

Study Notes

Cell Respiration Overview

Living cells need energy from outside sources to perform work, including assembling polymers, transporting materials across membranes, moving, and reproducing.
Animals obtain energy by consuming other animals or photosynthetic organisms.
Energy flows into an ecosystem as sunlight and leaves as heat.
Chemical elements essential for life are recycled.
Photosynthesis produces O₂ and organic molecules, which are used in cellular respiration.
Cells use chemical energy stored in organic molecules to generate ATP, which powers cellular work.
Catabolic pathways release stored energy by breaking down complex molecules.
Electron transfer plays a role in catabolic pathways, which are central to cellular respiration.

Catabolic Pathways and ATP Production

The breakdown of organic molecules is considered exergonic.
Fermentation is an anaerobic process involving partial sugar degradation.
Aerobic respiration requires oxygen, consumes organic molecules, and produces ATP.
Anaerobic respiration is similar to aerobic respiration, but uses compounds other than oxygen as the electron acceptor.
Cellular respiration encompasses both aerobic and anaerobic respiration, but typically refers to aerobic respiration.
Carbohydrates, fats, and proteins are fuels, but glucose is often used as an example in tracing cellular respiration.
The general formula for cellular respiration using glucose is: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + Energy (ATP + heat).

Redox Reactions

Transferring electrons during chemical reactions releases energy stored in organic molecules.
This energy is utilized to synthesize ATP.
Redox reactions involve the transfer of electrons between reactants.
Oxidation is the loss of electrons, while reduction is the gain of electrons. This is often remembered with the mnemonic "LEO the lion says GER".

The Principle of Redox

Chemical reactions that transfer electrons between reactants are called redox reactions.
During oxidation, a substance loses electrons.
During reduction, a substance gains electrons, leading to a decrease in positive charge.

Stepwise Energy Harvest via NAD+ and the Electron Transport Chain

Cellular respiration involves the step-wise breakdown of glucose and other organic molecules.
Electrons from organic compounds are often initially transferred to NAD+, a coenzyme.
NAD+ acts as an oxidizing agent during cellular respiration.
The reduced form of NAD+, NADH, stores energy that is used to synthesize ATP.

The Stages of Cellular Respiration: A Preview

Harvesting energy from glucose involves three stages: -1. Glycolysis -2. The citric acid cycle, also known as the Krebs cycle. -3. Oxidative phosphorylation.

Glycolysis

Glycolysis breaks down glucose into two pyruvate molecules in the cytosol.
It consists of two major phases: energy investment and energy payoff phases.
Glycolysis occurs regardless of the presence or absence of oxygen.

Oxidation of Pyruvate to Acetyl CoA

Prior to entering the citric acid cycle, pyruvate is converted to acetyl CoA.
This process links glycolysis to the citric acid cycle.
This step involves a multienzyme complex that catalyzes three reactions: oxidation of pyruvate and release of CO₂, reduction of NAD+ to NADH, and combination of the remaining two-carbon fragment with coenzyme A to form acetyl CoA

The Citric Acid Cycle

The citric acid cycle, or Krebs cycle, completes the breakdown of pyruvate to CO₂.
The cycle oxidizes organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH₂ per turn.
The cycle comprises eight steps, each catalyzed by a specific enzyme.
Citrate is formed by combining acetyl CoA with oxaloacetate.
The cycle decomposes citrate back to oxaloacetate.
NADH and FADH₂ carry electrons to the electron transport chain.

Oxidative Phosphorylation

Oxidative phosphorylation is the process that generates most of the ATP in cellular respiration.
It involves two major components: the electron transport chain and chemiosmosis.

The Pathway for Electron Transport

The electron transport chain, located in the inner membrane (cristae) of the mitochondrion, consists of protein complexes.
Electrons drop in free energy as they move through the chain and eventually combine with oxygen, forming water.
Electron carriers alternate between reduced and oxidized states during electron transfer.

Chemiosmosis

The energy released during electron transport is used to pump H⁺ from the mitochondrial matrix to the intermembrane space.
H⁺ moves down its concentration gradient back to the matrix through ATP synthase.
ATP synthase utilizes the flow of H⁺ to phosphorylate ADP to ATP.

An Accounting of ATP Production

During cellular respiration, most energy flows in the order: glucose → NADH → electron transport chain → proton-motive force → ATP.
Approximately 34% of the energy from glucose is transferred to ATP, yielding about 32 ATP.
The rest of the energy is lost as heat.

Fermentation

Fermentation enables cells to produce ATP without oxygen.
In fermentation, glycolysis is followed by reactions that regenerate NAD+.
Two common types are alcohol fermentation and lactic acid fermentation.
In alcohol fermentation, pyruvate is converted to ethanol and CO₂.
In lactic acid fermentation, pyruvate is reduced to lactate.
Obligate anaerobes require either fermentation or anaerobic respiration.
Facultative anaerobes can use either fermentation or cellular respiration depending on oxygen availability.

Evolutionary Significance of Glycolysis

Glycolysis is a very ancient metabolic pathway.
Early prokaryotes likely used glycolysis to produce ATP before oxygen was prevalent.
It is the most widespread metabolic pathway on Earth.
It occurs in the cytosol and does not require membrane-bound organelles, making it simpler.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on cellular respiration, including glycolysis and the electron transport chain. This quiz covers the roles of NADH, FADH2, and ATP production, along with key processes and concepts associated with energy metabolism. Perfect for students in biology or biochemistry courses!