Glycolysis + Gluconeogenesis Flashcards
What is the major substrate supply for gluconeogenesis
The major substrate supply for gluconeogenesis is protein , dietary protein ( which comes from diet food ) and endogenous protein ( which synthesized inside the cells )
Gluconeogenesis occurs in which organs ?
Gluconeogenesis proceeds only in the liver and kidneys
In the process of gluconeogenesis which synthesize the most of the glucose ?
The liver —> because it is a five time larger than the two kidneys
Which areas of the body where the process of gluconeogenesis does not occur ?
The pathway of gluconeogenesis does not occur in the brain, fat tissue and skeletal muscle !
The amino acids are very important for the process of gluconeogenesis ! These amino acids comes from ?
These amino acids comes from the catabolic process ( breaking down ) of protein molecules
Why amino acids are very important for the process of gluconeogenesis
Because those amino acids can be converted to pyruvate or any of the TCA cycle intermediates can serve as substrates for gluconeogenesis , and are therefore called glucogenic
The importance of gluconeogenesis
- gluconeogenesis ensures stable blood glucose levels between meals
- gluconeogenesis also enables us to maintain the necessary glucose levels when we take a diet that is rich in protein but low in carbohydrates
Gluconeogenesis
Glucose is a key metabolic in human metabolism , but it is not always available at sufficient levels in the diet , therefore, a pathway exists that converts other foodstuffs into glucose this pathway is called gluconeogenesis
The importance of glucose
- The brain requires at least ~50% of its calories in the form of glucose
- red blood cells exclusively subsist on glucose
- glucose is a precursor of other sugars needed in the biosynthesis of nucleotides , glycoprotein and glycolipids .
The two enzymatic steps of gluconeogenesis .
The first one
Pyruvate > oxaloacetate
By pyruvate carboxylase
The second one
Oxaloacetate > PEP
By phosphoenolpyruvate carboxykinase
The two hydrolytic steps of gluconeogenesis
Fructose-1,6-bisphosphate + H2O»_space; fructose-6-phosphate + inorganic phosphate
By fructose-1,6-bisphosphatase enzyme
Glucose-6-phosphate + H2O»_space; glucose + inorganic phosphate
By glucose -6- phophatase
The energy requiring in gluconeogenesis
Gluconeogenesis requires an input of six ATP or GTP for each molecule of glucose
Steps that require energy in glycolysis
Step one
“ phosphorylation of glucose “»_space; require one molecule of ATP .
Step three
“ phosphorylation of fructose-6-phosphate»_space; one ATP molecule required .
Steps that release energy in glycolysis
Step six
“ oxidative phosphorylation of glyceraldehyde-3-phosphate “»_space; reduction of 2 NAD+ release 2 NADH
Step seven
“ substrate - level phosphorylation “»_space; high energy phosphate group is transferred to ADP to form ATP .
Step ten
“ substrate - level phosphorylation “»_space; high energy phosphate group in PEP is transferred to ADP to form ATP .
Net gain of anaerobic glycolysis
Net gain of two ATP
