Basic concepts of cellular metabolism, glycolysis & gluconeogenesis Flashcards
What is Metabolism?
Sum of all the chemical transformations taking place in a cell or organism via a series of enzyme-catalysed reactions that constitute metabolic pathways
What is Biosynthesis used for?
Anabolism (Requires energy)
What is Degradative used for?
Catabolism (Releases energy)
What does amylase break starch into?
Maltose
Why is Glucose a versatile biochemical precursor?
Bacteria can use glucose to build the carbon skeletons of:
-All the amino acids
-Membrane lipids
-Nucleotides in DNA and RNA
-Cofactors needed for the metabolism
Why is glucose an excellent fue?
- Yields good amount of energy upon oxidation
- Can be efficiently stored in the polymeric form
- Many organisms and tissues can meet their energy needs only with glucose
What is the major pathway of Glucose Utilization, oxidating via glycolysis?
Glucose becomes Pyruvate (Obtaining energy - ATP)
How does Glucose becomes RIbose 5-phosphate?
Oxidation via pentose phosphate
What is Glycolysis?
Glucose molecule is converted into pyruvate in a sequence of enzyme-catalyzed reactions
What is the purpsoe of Pyruvate
- Used for aerobic oxidation (citric cycle)
- Used in biosynthesis
What are the functions of Glycolysis?
- Energy is released ATp and NADH)
- Fermentation
Does Glycolysis occur in anaerobic conditions?
Yes
Why should the cell phsophorylate?
- No transporters for phosphroylated sugars
- Phosphoryl groups good in conserving metabolic energy
- Phosphoryl group binding to enzyme lowers activation energy
What is the role of ATP to phsphofructokinase?
Acts as an allosteric regulator
What is th erole of AMP in phosphofructokinase?
Competes with ATP for attachment to the allosteric site and reverses the inhibitory effect of ATP
What is the role of Citrate in phosphofructokinase?
Citrate promotes the binding of ATP to the allosteric site
What is GLUT?
Glucose Transporter
What happens when citrate accumulates in the citric acid cycle?
The energy is overactive and should slow down
What does high hydrogen ion concentration (low pH) indicate?
Increase in the allosteric effect of ATP
What occurs to active muscle tissue due to anaerobic conditions?
Pyruvate is converted to lactate
What does excess lactate bring about?
Acidosis - Lowering of pH
Why at low pH values glycolysis slows down reducing the production of lactate?
Hydrogen ion inhibition of phosphofructokinase
Why is Glucagon released by the pancreas?
Drop in glucose levels in the blood
CONTINUE FROM SLIDE 30
In the inhibition of pyruvate kinase, what slows down pyruvate kinase?
Mg ions that are sequestered by ATP when in excess
What is function of GLUT 1 and 3?
Transporting glucose in cell under normal conditions
Where can GLUT 1 and 3 be found in tissue locations?
Mammalian tissues
What is the function of GLUT 2?
Glucose enters the cells only when there is lots of glucose in the serum (e.g after a calorie rich meal)
Where can GLUT 2 be found?
Liver and pancreatic beta cells
Why does GLUT 4 increase on muscle and fat cells?
Due to release of insulin
What happens during excerise?
Lactate builds up in the muscles
What happens when lactate is transported to the liver?
Converted to glucose
What does yeast do to glucose?
Ferments glucose to ethanol
What happens to Lactate in the Liver?
Lactate enters the liver and it is coverted to pyruvate by lactate dehydrogenase
What is the cofactor that reacts with lactate dehydrogenase to covert lactate to pyruvate?
NAD+
What is the process called turning pyruvate to glucose?
Gluconeogenesis
What is the process to turn glucose to pyruvate in the muscle?
Glycolysis
What cofactor is used to react with lactate dehydrogenase to convert pyruvate to lactate?
NADH and H+
What happens when glucose is low in glycolysis or glucongenesis?
Fructose-2,6 biphsophate is dephosphorylated into fructose 6-phosphate - no binding to phosphofructokinase
How does glucosed 6 phosphae become pentose phsophate?
Oxidation
In wha phase is RIbulose 5 phosphate used to return to Glucose 6-phosphate?
Nonoxidative phase
What is the role of NADPH in he penose phosphae pathway?
Inhibiting the glucose 6 phosphae dehydrogenase
What is Pentose Phosphate pathway?
A process by which cells generate reducing power (NADPH) ha is needed for biosynthesis
What is Gluconeogensis?
Process by which cells can use a variey of meabolies for the synthesis of glucose
What is the process of glycolysis?
Process by which cells can exract a limited amoun of energy from glucose under anaerobic conditions
GO OVER THE DIAGRAMS FROM LECTURE 15
