Cellular Respiration: Glycolysis to Krebs Cycle

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Questions and Answers

What substance is formed from pyruvate during lactic acid fermentation?

Ethanol

Lactic Acid (correct)

Carbon Dioxide

Acetic Acid

What is the role of NADH in lactic acid fermentation?

It acts as an electron donor. (correct)

It breaks down fatty acids.

It becomes an inhibitor.

It is used to produce glucose.

Why is NADH considered the limiting reagent in lactic acid fermentation?

It is consumed faster than it can be produced. (correct)

It catalyzes reactions in excess.

It is produced in excess amounts.

It is not needed for glycolysis.

Which of the following is NOT a direct outcome of lactic acid fermentation?

Production of ethanol Signup and view all the answers

In the context of fermentation, what is the overall purpose of converting NADH back to NAD+?

To facilitate glycolysis. Signup and view all the answers

What is the primary purpose of photosynthesis?

To produce sugars Signup and view all the answers

During intense workouts, what physiological condition causes the burning sensation in muscles?

Lactic acid buildup Signup and view all the answers

What are the byproducts of splitting water during the light dependent reactions?

Oxygen and electrons Signup and view all the answers

What does NADP become after capturing hydrogen during the light reactions?

NADPH Signup and view all the answers

What would be the result of lactic acid fermentation in human cells?

Production of lactic acid and NAD+ Signup and view all the answers

Which type of fermentation occurs in yeast and bacteria, resulting in ethanol production?

Alcoholic fermentation Signup and view all the answers

Which process uses ATP in the combination of CO2 with hydrogen and electrons?

Calvin cycle Signup and view all the answers

What is produced from two G3P molecules?

Glucose Signup and view all the answers

Which of the following is NOT an input for the light dependent reactions?

Carbon dioxide Signup and view all the answers

What happens to ATP at the end of the light dependent reactions?

It breaks down into ADP and inorganic phosphate Signup and view all the answers

Which factor is NOT mentioned as essential for maximum photosynthesis efficiency?

Soil nutrient levels Signup and view all the answers

What is the primary purpose of the investment phase in glycolysis?

To consume ATP Signup and view all the answers

How many ATP are produced in the payout phase of glycolysis?

Four ATP Signup and view all the answers

What occurs when pyruvate enters the mitochondria?

It loses one molecule of CO2 Signup and view all the answers

What is the primary subject of the upcoming PBL mentioned?

Photosynthesis Signup and view all the answers

Which molecule is formed after NAD+ captures hydrogen and electrons during the Krebs cycle?

NADH Signup and view all the answers

Why is the average score highest on the third test according to the instructor?

It is taken after the withdrawal date. Signup and view all the answers

What is the total number of carbon dioxides released when one molecule of glucose is metabolized?

Six CO2 Signup and view all the answers

How many ATP are produced per pyruvate during the breakdown of glucose?

One ATP Signup and view all the answers

What should students aim for according to the instructor when preparing for the third test?

To be able to summarize key concepts on one sheet Signup and view all the answers

During which week is the fourth exam scheduled?

During finals week Signup and view all the answers

What is produced at the end of the Krebs cycle?

Carbon Dioxide Signup and view all the answers

What is the net gain of ATP from glycolysis after considering the investment phase?

Two ATP Signup and view all the answers

Which of the following best describes the instructor's attitude towards students’ performance on the third test?

Encouraging, based on previous years' results Signup and view all the answers

What is the primary input molecule in the glycolysis process that yields the highest output of ATP?

Glucose Signup and view all the answers

What does NAD+ become after it merges with released electrons and hydrogen during glycolysis?

NADH Signup and view all the answers

How many molecules of ATP are required to initiate the glycolysis process, and how many are produced?

2 ATP required, 4 produced Signup and view all the answers

In the context of metabolism, what is pyruvate derived from?

The breakdown of glucose Signup and view all the answers

What economic concept is used to describe the energy yield of glycolysis?

Return on investment Signup and view all the answers

What is the significance of breaking carbon-carbon bonds in glucose?

It releases hydrogen and electrons. Signup and view all the answers

Which statement accurately reflects the comparison between glucose and fat regarding energy yield?

Fat contains more carbon-carbon bonds than glucose. Signup and view all the answers

What role does glucose play in cellular respiration compared to other potential inputs?

Glucose is the first step in aerobic respiration. Signup and view all the answers

Study Notes

Glycolysis

Glycolysis is the first stage of cellular respiration, occurring in the cytoplasm.
It involves breaking down glucose (C6H12O6) into two pyruvate molecules (C3).
Two ATP molecules are invested in the initial stages (investment phase).
Four ATP molecules are produced in the later stages (payout phase), resulting in a net gain of 2 ATP.
During bond breaking, electrons and hydrogen ions (H+) are released.
NAD+ accepts these released electrons and hydrogen ions, becoming NADH.

Krebs Cycle

The Krebs Cycle (also known as the Citric Acid Cycle) takes place within the mitochondria.
Pyruvate enters the mitochondria and releases one molecule of CO2 per pyruvate.
The remaining portion of pyruvate binds with coenzyme A to form acetyl-CoA.
Acetyl-CoA enters the Krebs Cycle, where it's further broken down, releasing more CO2.
NAD+ and FAD accept electrons and hydrogen ions, becoming NADH and FADH2 respectively.

Electron Transport Chain

The electron transport chain occurs within the inner membrane of the mitochondria.
Electrons from NADH and FADH2 power the electron transport chain.
The energy released from electron movement is used to pump protons (H+) across the membrane, creating a proton gradient.
This gradient is used by ATP synthase to produce ATP.

Fermentation

Fermentation occurs when oxygen is limited (anaerobic conditions).
In lactic acid fermentation, pyruvate is converted to lactic acid, regenerating NAD+ from NADH.
This process happens in human muscles during strenuous exercise.
Alcoholic fermentation, common in bacteria and yeast, converts pyruvate to ethanol and CO2, also regenerating NAD+.

Photosynthesis

Photosynthesis is a process used by plants and some bacteria to convert light energy into chemical energy (sugars).
It occurs in chloroplasts and has two main stages: the light-dependent reactions and the light-independent reactions.

Light-Dependent Reactions

The light-dependent reactions require light as an energy source.
Water is split, releasing oxygen, electrons, and hydrogen ions (H+).
Electron transport chains are involved, pumping hydrogen ions across membranes, creating a proton gradient.
ATP is produced using this proton gradient, and NADP+ accepts electrons and protons, becoming NADPH.

Light-Independent Reactions (Calvin Cycle)

The light-independent reactions do not require light directly.
They use the ATP and NADPH generated in the light-dependent reactions to fix carbon dioxide.
CO2 is combined with hydrogen ions and electrons from NADPH, using energy from ATP.
This process results in the formation of G3P (glyceraldehyde 3-phosphate) molecules.
Two G3P molecules combine to form glucose.

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Description

Explore the stages of cellular respiration, focusing on glycolysis, the Krebs cycle, and the electron transport chain. Understand how glucose is broken down to produce ATP, releasing energy and CO2. This quiz will test your knowledge of these crucial biochemical processes.