Name the complex where FADH 2 enters electron transport.

Hi everyone. Our next question says which complex is the primary entry point for electrons from N A DH in the electron transport chain? A complex one B complex two C complex three or D complex four. So let's recall that N A DH is one of the electron carriers that brings electron electrons from the citric acid cycle. So bringing electrons from the oxidation of glucose and bringing them to the electron transport chain. So we're looking at the entry points at the beginning of the electron transport chain and recall it, there's two different places where electrons enter from these electron carriers. But N A DH is the higher energy electron carrier. So its electrons enter on choice. A complex one right at the beginning of electron transport chain at the highest energy, the complex two entry point is where electrons enter that are being carried by fa DH two. They are at a slightly lower energy level. And so have to enter the electron transport chain downhill of the electrons from N A DH. So that's why choice B is incorrect. And then of course, choices C and D are farther along in the electron transport chain after electrons have entered from outside. So complex three receives electrons from co enzyme Q or ubiquinone and transfer them to transfers them to cytochrome c. While complex four receives those electrons from cytochrome C and then transfers them to oxygen that final electron acceptor. So once again, our primary entry point for electrons from N A DH and the electron transport chain is choice a complex one. See you in the next video.

Table of contents

Skip topic navigation

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

21. The Generation of Biochemical Energy

Electron Transport Chain

GOB Chemistry

21. The Generation of Biochemical Energy

Electron Transport Chain

Previous problemNext problem

1:58 minutes

Problem 44

Textbook Question

Name the complex where FADH₂ enters electron transport.

Verified step by step guidance

Understand that FADH₂ is a molecule involved in cellular respiration, specifically in the electron transport chain, which is part of oxidative phosphorylation.

Recall that the electron transport chain consists of a series of protein complexes embedded in the inner mitochondrial membrane, numbered I through IV.

Identify that FADH₂ donates electrons directly to Complex II (succinate dehydrogenase), bypassing Complex I, unlike NADH which donates electrons to Complex I.

Note that Complex II is unique because it is also part of the citric acid cycle, where it catalyzes the oxidation of succinate to fumarate while reducing FAD to FADH₂.

Conclude that the complex where FADH₂ enters the electron transport chain is Complex II (succinate dehydrogenase).

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electron Transport Chain (ETC)

The Electron Transport Chain is a series of protein complexes and other molecules located in the inner mitochondrial membrane. It plays a crucial role in cellular respiration by transferring electrons from electron donors like NADH and FADH₂ to electron acceptors, ultimately leading to the production of ATP through oxidative phosphorylation.

FADH₂

FADH₂ is a reduced form of flavin adenine dinucleotide, a coenzyme involved in various metabolic reactions. It is produced during the Krebs cycle and serves as an electron carrier in the Electron Transport Chain, contributing to ATP synthesis by donating electrons to Complex II of the ETC.

Complex II (Succinate Dehydrogenase)

Complex II, also known as succinate dehydrogenase, is one of the four main protein complexes in the Electron Transport Chain. It is responsible for the oxidation of succinate to fumarate in the Krebs cycle and facilitates the transfer of electrons from FADH₂ to ubiquinone, marking the entry point of FADH₂ into the ETC.

Watch next

Master Intro to Electron Transport Chain Concept 1 with a bite sized video explanation from Jules

Start learning