Hypoxia & Tumors Video Flashcards
Where is lactic acid produced?
Lactic acid is mainly produced in muscle cells and red blood cells
What is the purpose of generating lactic acid?
The purpose of generating lactic acid is to replenish NAD+ in the muscles so that glycolysis can run continuously
When is lactic acid formed?
L.A is formed when glucose is used for energy at low oxygen
Intense exercise
Infection or disease
What is the final product of glycolysis?
Pyruvate is the final product of glycolysis
Which enzyme converts pyruvate to lactate?
The enzyme is lactate dehydrogenase converts pyruvate to lactate
Upregulation of lactate dehydrogenation — high amount will trigger this reaction
NAD+ is formed when Lactase dehydrogenase converts pyruvate to lactate
Where does NAD+ go in the Cori Cycle
NAD+ stays in the muscle for continuous glycolysis
Where does lactate go?
Muscles do not want lactate
Exported to the liver for conversation to glucose
Describe the Cori Cycle
Cori cycle is:
Lactate acid being produced in muscles and then exported to the liver for gluconeogenesis
(Lactate will be converted back to pyruvate and follow gluconeogenesis)
Glucose can be re supplied to the muscles
Increase ATP or replenish glycogen stores in muscle
How many ATP for immediate use via glycolysis?
We get two ATP for immediate use for every glucose molecule that goes through glycolysis
What is the net balance of ATP in the Cori Cycle?
6 ATP molecules is required every time you want to produce glucose via gluconeogenesis in the liver
It’s expensive!
I have produced 2 through glycolysis
So each iteration of the Cori cycle costs 4 ATP — fine on a temporary basis, when ATP needs are immediate
What is the metabolic function of the Cori Cycle?
The function of the Cori Cycle is to shift the metabolic burden from the muscles to the liver during intense exercise
Which transcription factor protein is present when there is no oxygen?
One major protein known as HIF-1 (hypoxia inducable factor)
It is a transcription factor — helps to make other proteins
It is the statement that there is no oxygen present
Where does HIF-1a go in normal conditions?
In normal oxygen conditions HIF-1a stays in the cells.
It is hydroxylated and degraded
Get rid of the HIF if we have oxygen
Where does HIF-1a go in hypoxic conditions?
Under hypoxic conditions, HIF-1a is not degraded, instead it goes into the nucleus and forms a complex known as a HIF-1 complex
Bind DNA and initiate a hypoxic response
It’ll upregulate Lactate Dehydrogenase! To make lactate!
Describe what happens to HIF-1a in tumour conditions
In a tumor
HIF 1a is in very high levels in tumor environments, it’s not being degraded even in normal oxygen conditions!
If HIF is there, the cell is behaving like there is no oxygen — won’t degrade HIF — we’re running aneorabic respiration!
It’s called the Warburg Effect
