Citric Acid Cycle and Redox Reactions

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Questions and Answers

Which molecule is produced after the removal of 1 carbon from pyruvate in step 1?

Acetyl-CoA (correct)

Lactate

Oxaloacetate

Fumarate

What is produced during the link reaction of the TCA cycle?

NADPH

NADH (correct)

ATP

FADH2

What is the process called where the position of atoms within a molecule is changed in step 2?

Oxidation

Phosphorylation

Isomerisation (correct)

Reduction

How many carbons does the pyruvate molecule contain before the link reaction?

3 Signup and view all the answers

Which of the following is a correct description of the link reaction in the TCA cycle?

A 2 carbon molecule called Acetyl-CoA is formed from pyruvate Signup and view all the answers

What energy-carrying molecule is produced in Step 5?

GTP Signup and view all the answers

Which enzyme helps join GDP and phosphate group in Step 5?

Ligase Signup and view all the answers

What process in Step 5 provides the energy needed for the reaction?

Breaking thioester bond Signup and view all the answers

What type of molecule is produced along with FADH2 in Step 6?

NADH Signup and view all the answers

Which enzyme assists in changing the molecule back to its original 4 carbon form in Step 6?

Oxidoreductase Signup and view all the answers

What happens to electrons in a redox reaction?

Electrons are transferred Signup and view all the answers

Which enzyme is involved in making or breaking double bonds between carbon atoms?

Ligase Signup and view all the answers

What molecule is reformed in step 8 during the citric acid cycle?

Oxaloacetate Signup and view all the answers

What is produced by transferring electrons to NAD+ during the citric acid cycle?

NADH Signup and view all the answers

Which statement accurately describes the citric acid cycle?

The citric acid cycle can occur in the presence or absence of oxygen Signup and view all the answers

What is released when a three carbon molecule breaks down in the citric acid cycle?

One CO2 Signup and view all the answers

How many carbon atoms are left after a three carbon molecule breaks down?

Two Signup and view all the answers

What does the two carbon molecule do after it is created?

It enters the cycle where it undergoes various reactions Signup and view all the answers

What happens when the two carbon molecule joins with a four carbon molecule?

It forms a six carbon molecule Signup and view all the answers

What happens to the six carbon molecule in the citric acid cycle?

It loses two carbon dioxide molecules Signup and view all the answers

What happens to the 6 carbon molecule in Step 3?

One carbon dioxide is removed, changing it to a 5 carbon molecule Signup and view all the answers

What is reduced to NADH in Step 3?

NAD+ Signup and view all the answers

What is the role of oxidoreductase in Step 3?

Helps the redox reaction happen Signup and view all the answers

What changes occur to the 5 carbon molecule in Step 4?

It becomes a 4 carbon molecule by removing CO2 Signup and view all the answers

Which molecule captures electrons in Step 4?

NAD+ Signup and view all the answers

Study Notes

Citric Acid Cycle (TCA Cycle)

Step 1: Link Reaction

Links with glycolysis
3-carbon pyruvate molecule is converted into 2-carbon Acetyl-CoA
1 carbon is removed as CO2
NADH is produced in the process

Step 2: Isomerization

Atoms (hydrogen) within the molecule are rearranged
Rearranged molecule is used in further reactions in the cycle

Step 3

1 carbon dioxide is removed, changing 6-carbon molecule to 5-carbon molecule
Oxidoreductase enzymes assist in this process
NAD+ is reduced to NADH, gaining electrons
Energy is captured in the form of NADH

Step 4

CO2 is removed, changing 5-carbon molecule to 4-carbon molecule
NAD+ is reduced, producing more NADH by capturing electrons
Oxidoreductase enzymes help in the process

Step 5

Produces GTP (energy-carrying molecule)
Phosphate group is added to GDP, converting it to ATP
Breaking thioester bond provides energy for the reaction
Ligase enzyme helps join GDP and phosphate group, making ATP

Step 6

Molecule is changed back to the original 4-carbon molecule
Oxidoreductase assists in this process
Reaction produces NADH + FADH2, storing energy for later
Completing the cycle to produce more energy

Step 7

Electrons are transferred, changing the molecular structure
Ligase enzyme helps make/break double bonds between carbon atoms

Step 8

4-carbon molecule oxaloacetate is reformed
Redox reaction occurs, producing more NADH by transferring electrons to NAD+

Redox Reactions

Oxidation = loss of electrons
Reduction = gain of electrons

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Description

This quiz covers the Citric Acid cycle, redox reactions, and the role of enzymes in forming and breaking chemical bonds.