Cherri Taite
HSCI 4661
Dr. Chen
09 October 2024
Assignment #3. Due October 9 midnight (5 points)
In your own words, please answer the following questions:
What are the key control steps of glycolysis? How are the 3 key enzymes controlled?
For each of the regulator, why are they there to positively or negatively regulate the
enzyme and where do they come from? (3 pts)
The enzymes that catalyze reactions #1, 3, and #10 of glycolysis act as key control steps of
glycolysis:
Reaction 1: Hexokinase is inhibited by
high levels of the product glucose-6-phosphate.
Reaction 3: Phosphofructokinase and the phosphorylation of fructose 6 phosphate.
Inhibitors : high ATP, citrate (only works when ATP is high in cytosol), hydrogen
ions (high energy status
Activators: AMP/ADP, fructose-2,6-phosphate
Reaction 10: Pyruvate kinase
Inhibitors: ATP, Acetyl CoA
Fructose-1-6-bisphosphate.
Acetyl-CoA iinhibits the enzyme pyruvate kinase allosterically
high ATP, citrate (only works when ATP is high in cytosol), hydrogen ions (high
energy status)
. What are the positive and negative regulators of Pyruvate Dehydrogenase (PDH) and
why is it important for them to regulate PDH?
Positive:
ADP
Ca2+
High pyruvate concentration
Negative:
Acetyl COA accumulation from beta oxidation
NADH. NADH Is formed in abundancy from beta oxidation in the mitochondria. High in
ADHD ratio indicates the cell has sufficient energy and therefore has no need to go
through citric acid cycle.
Phosphorylation – Pyruvate dehydrogenase is phosphorylated by pyruvate
dehydrogenase kinase during high energy states / when ATP is high when ATP is high
What are the regulators of Citrate Synthase? Why are they there and where do they
come from?
High ATP/ADP ratio
