5: Biochemistry - Gluconeogenesis Flashcards
Between meals, when dietary carbohydrate is exhausted but there’s still glycogen in the liver, which process supplies the bloodstream with glucose?
Glycogenolysis
When hepatic glycogen stores are depleted, i.e glycogenolysis is no longer any good, how does the body supply the bloodstream with glucose?
Gluconeogenesis
What is gluconeogenesis?
Synthesis of glucose from NON-CARBOHYDRATE PRECURSORS
What’s an emergency situation in which gluconeogenesis would be required?
Prolonged starvation
What molecule, produced by skeletal muscle during anaerobic respiration, acts as a precursor for gluconeogenesis?
Lactate
Which molecules, usually acting as the building blocks of protein, can be used as precursors for gluconeogenesis?
Amino acids
How are amino acids obtained for gluconeogenesis?
Proteolysis of muscle protein
This is why you see muscle wasting during prolonged starvation
Which building block of triglycerides can be used by the body as a precursor for gluconeogenesis?
Glycerol
How are glycerol molecules obtained for gluconeogenesis?
Lipolysis of triglycerides in adipose (fat) tissue
Gluconeogenesis is an anabolic reaction (small molecules ⇒ big molecules) and therefore requires energy. How is this energy obtained?
Oxidation of fatty acids from adipose tissue
This, along with proteolysis of muscle, is why starving people lose weight
Where does gluconeogenesis occur?
Liver
Gluconeogenesis is essentially the reverse of ___.
glycolysis
Which molecule accepts acetyl groups from fat breakdown?
Oxaloacetate
Gluconeogenesis is very energetically ___.
expensive
How many ATPs worth of energy are required to synthesise one molecule of glucose?
6
In the liver, lactate (lactic acid) is converted into ___ which is then converted into glucose.
Pyruvate
remember this is the opposite of glycolysis, where pyruvate is converted to lactic acid
What must amino acids be converted to before this molecule can be converted into glucose?
Oxaloacetate
Which molecules regulate glycolysis and gluconeogenesis at a systemic level?
Hormones
When glucagon levels are high, glycolysis is (stimulated / inhibited) and gluconeogenesis is (stimulated / inhibited).
Glycolysis is inhibited
Gluconeogenesis is stimulated
When insulin levels are high, glycolysis is (stimulated / inhibited) and gluconeogenesis is (stimulated / inhibited).
Glycolysis is stimulated
Gluconeogenesis is inhibited
Gluconeogenesis is regulated at a systemic level. It is also controlled by individual ___.
cells
In an individual cell, if [AMP] or [ADP] were high, what would occur to the rate of gluconeogenesis?
Low energy so gluconeogenesis would be inhibited (as it’s energetically active)
In an individual cell, if [ATP] was high, what would happen to the rate of gluconeogenesis?
High energy - so gluconeogenesis would be encouraged
High concentrations of molecules associated with the TCA cycle (stimulate / inhibit) glycolysis and (stimulate / inhibit) gluconeogenesis.
Inhibit glycolysis
Stimulate gluconeogenesis
