HUN1201 Exam III Study Guide
What are the 3 possible fates of glucose in the liver?
Phosphorylated and stored, phosphorylated and used by the liver,
released for other cells to use, or stored as triglycerides in adipose tissue.
Fructose and galactose can either be converted into glucose, or
channeled into the glycolysis pathway for energy production.
What are the 3 Phases of glucose oxidation?
Glycolysis(occurs in the cytosol, anaerobic, six carbon glucose
converted into 2 3carbon pyruvates) TCA cycle, Oxidative
What are the starting products, and ending products of each phase?
Glycolysis starts with a six carbon glucose, and ends with 2 3
carbon pyruvates. Glucose is phosphorylated to yield glucose 6
phosphate and ADP. Then enzymes turn it into pyruvate. Produces
a net of 2 ATP. Oxidative because yields hydrogen, picked up by
NAD (niacin) to form the reduced NADH. If not used immediately,
pyruvate can be converted back into glucose. In the absence of
oxygen, glucose is converted to lactic acid. Occurs when there isn’t
a mitochondria or in muscles during high intensity exercise and
does not yield ATP, and regenerates NAD+ for glycolysis. When
oxygen is present, pyruvate is converted to a acetyl CoA, which
occurs in the mitochondria. The CoA comes from the coenzyme
pantothenic acid (b vitamin). This pathway generates NADH+H
from the niacin coenzyme NAD+. Once pyruvate becomes acetyl
CoA, it cannot be returned to glucose. Acetyl CoA can either enter
the TCA cycle or go into fatty acid synthesis. So glycolysis starts
with glucose and ends with pyruvate, and the transition turns
pyruvate into acetyl CoA.
The TCA cycle is a continuous circle of 8 metabolic reactions. It is
located in the mitochondria. Acetyl CoA enters the cycle, but cannot
return to acetyl CoA. Oxaloacetate (from dietary carbs) and other
metabolic intermediates within the TCA cycle are necessary for
continued functioning of the TCA cycle. Glucose from carbs enters
the TCA cycle and is converted to oxaloacetate in order to help
further the cycle for other glucose. When acetyl CoA is made, it
mixes with oxaloacetate to form 6 carbon citrate. At the end of TCA,
1 GTP, 8 H, and 2 CO2 are produced. From glycolysis and TCA,
one molecule of glucose produces 6 CO2, 2 ATP, 2 GTP, and 10
The reduced coenzymes of NADH and FADH2 link the TCA cycle to
stage 3 by the electron transport chain. Oxidative phosphorylation
occurs in the electron transport chain. Proteins, called electron
carriers accept and donate electrons. Everytime an electron is