Carbohydates And Glycolysis Flashcards
What makes up Sucrose?
Glucose and Fructose disaccharide
What makes up Lactose?
Galactose and Glucose disaccharides
What makes up Maltose?
Two glucose disaccharides
Describe some of the enzymes in the body used to digest carbohydrates.
Salivary Amylase into Dextrins
Pancreatic Amylase into monosaccharides
Disaccharidases attached to membrane of epithelial cells in small intestine:
Lactase, Sucrase, Isomaltase and Pancreatic Amylase
Why cant humans hydrolyse Cellulose?
No enzymes to break down the beta 1-4 glycosidic linkages that are present in Cellulose
Name and describe the 3 types of Lactose Intolerance
Primary, Secondary and Congenital Lactase Deficiency
Primary - Absence of Lactase persistence allele, only in adults
Secondary - Caused by small intestine injury (crohn’s, coeliac, ulcerative colitis etc.), adults and infants, reversible
Congenital - (RARE) Autosomal Recessive defect in Lactase Gene, cannot digest breast milk
Describe the Sodium Glucose transport mechanism
Sodium attaches to Glucose in Ileum
Facilitated diffusion into epithelial cell
Sodium-potassium pump between cell and blood maintains conc. gradient between ileum and epithelial cell (uses ATP)
Name all the intermediates and compounds during glycolysis, in order.
Glucose Glucose 6-P Fructose 6-P Fructose 1,6 bis-P DHAP or Glyceraldehyde 3-P 1,3-bis-P-glycerate 3-P-glycerate 2-P-glycerate Phosphoenolpyruvate Pyruvate
What is the net production of molecules during glycolysis?
2 ATP
2 NADH
2 H20
2 H+
During what steps are ATP lost/produced?
Step 1 - ATP lost
Step 3 - ATP lost
Step 7 - ATP gained x2
Step 10 - ATP gained x2
Where are the NADH molecules made?
The step converting Glyceraldehyde 3-P into 1,3-bis-phosphoglycerate
What 3 enzymes are we required to know?
Hexokinase (Glucokinase in liver) - Step 1
Phosphofructokinase-1 - Step 3
Pyruvate Kinase - Step 10
Which steps are irreversible in Glycolysis and why?
Steps 1, 3 and 10 because they have a very negative free energy change, hence lots of energy is needed to be put in to reverse the reaction
What is the benefit of the phosphorylation of Glucose to Glucose 6-P?
Makes glucose negative
Prevents passage back across plasma membrane
Why are there so many steps in glycolysis?
1) Reaction can be controlled
2) Versatile
- Useful intermediates
- Can connect to other pathways
- Reverse
3) Efficient energy conservation
4) Easier chemistry
What is LDH?
An enzyme which is needed to allow glycolysis to occur in anaerobic conditions.
How can we use glycolysis in cancer?
Glycolysis 200x greater in cancer
Uptake of radioactive Hexokinase can help locate tumour buildup using POSITRON EMISSION TOMOGRAPHY
Describe the entire 10 step process of glycolysis. Include enzymes, irreversible reactions and intermediates.
Use lecture
