Describe the process occurring in the matrix of mitochondria.

(N/A) The $TCA$ cycle (also known as the Citric Acid Cycle or Krebs cycle) occurs in the mitochondrial matrix.
$1$. The cycle starts with the condensation of an acetyl group (from Acetyl $CoA$) with oxaloacetic acid $(OAA)$ and water to yield citric acid. This reaction is catalyzed by the enzyme citrate synthase, and a molecule of $CoA$ is released.
$OAA$ $(4C) + \text{Acetyl } CoA (2C) + H_2O \xrightarrow{\text{Citrate synthase}} \text{Citric acid } (6C) + CoA$
$2$. Citrate is then isomerized to isocitrate.
$3$. This is followed by two successive steps of decarboxylation, leading to the formation of $\alpha$-ketoglutaric acid $(5C)$ and then succinyl-$CoA$ $(4C)$.
$4$. Succinyl-$CoA$ is oxidized to $OAA$ through several steps, allowing the cycle to continue. During the conversion of succinyl-$CoA$ to succinic acid, a molecule of $GTP$ is synthesized via substrate-level phosphorylation. In a coupled reaction, $GTP$ is converted to $GDP$ with the simultaneous synthesis of $ATP$ from $ADP$.
$5$. There are three points in the cycle where $NAD^+$ is reduced to $NADH + H^+$ and one point where $FAD^+$ is reduced to $FADH_2$.
$6$. The continued oxidation of acetyl $CoA$ via the $TCA$ cycle requires the continued replenishment of oxaloacetic acid and the regeneration of $NAD^+$ and $FAD^+$ from $NADH$ and $FADH_2$ respectively.
The summary equation for the oxidation of one molecule of pyruvic acid in the mitochondrial matrix is:
$\text{Pyruvic acid} + 4NAD^+ + FAD^+ + 2H_2O + ADP + Pi \xrightarrow{\text{Mitochondrial Matrix}} 3CO_2 + 4NADH + 4H^+ + FADH_2 + ATP$