Glucides 1.1: Flashcards
What kind of sugar is glucose
Aldose hexose
Enantiomers:
De-glucose: OH is a droite
L-glucose: OH is a gauche
How can you get glucose from manose?
Via an epimerase
This is because manose and glucose are epimeres
What can change the structure of glucides from cyclique to lineare?
EXAM QUESTION:
the pH
L’équilibre entre les formes varie en fonction de l’environnement
* À pH neutre, ≈99% cyclique (plus stable)
* À pH basique, ≈99% linéaire
Major glucose form in our bodies:
beta-delta- gluco pyranose (for cyclic)
Forme chaise en solution = plus stable
alpha vs beta bonds?
alpha bon : oh in the bottom, beta bond: OH on the top
3 dissacharides:
- Saccharose:
- D-glucose + D-fructose
- alpha bond
- Lactose:
- D-glucose et de D-galactose
- beta bond
- Maltose:
- D-glucose - D-glucose
*
Amidon, Saccharose and Lactose digestion
Amidon:
it is a polysaccaride to first broken into maltose then into glucose
Saccharose:
disacaride so directly broken itno glucose and fructose
Lactose:
disacchiride broken into glucose and galactose
GLUT that Responds to insulin
GLUT 4
insuline incresses its expression, problem in diabetics
What is special of GLUT2?
it is the glucosensor in glycolyse vs neoglycogenesis
Exam Question
What induces insulin secretion?
Les sucres
- Glucose
- Mannose
* Les acides aminés
- Leucine
- Arginine
* La stimulation du nerf vague
* Peptides entériques
Action of insulin
ACTIVATION de la synthèse de glycogène (glycogenèse)
* INHIBITION de la dégradation du glycogène (glycogénolyse)
* ACTIVATION de la dégradation de glucose (glycolyse)
* INHIBITION de la synthèse de glucose (néoglucogenèse)
* ACTIVATION de la synthèse des lipides (lipogenèse)
* INHIBITION de la dégradation des lipides (lipolyse
Glucagon role?
It is a hormone that wants to increase glucose levels in the blood
What is Glycogenèse?
The action of transforming glucose into glucogene to store it
Glucogenesis steps:
st step is important:
Glucose à Glucose-6-phosphate
hexokinase
UTP (UDP) is important for the synthesis of long chains
UDP-glucose + Glycogènen à Glycogènen+1 + UDP
What is Glycogénolyse?
Breakdown of glucogen to get glucose
important enzyme: glucose-6-phosphatase ** dans le foie uniquement **, exam q)
What is glycolyse?
Dégradation du glucose pour faire de l’énergie
Glycolyse
* Dans le cytosol
Cycle de Krebs
* Dans la mitochondrie
What does glycolysis lead to?
Glucose -> 2 pyruvate + 2 ATP + 2 NADH
Steps in glycolysis: (3 key ones)
- Synthèse du** glucose-6-phosphate** (étape 1)
Enzyme: Hexokinase
Input: Glucose
Output: glucose-6-phosphate - Synthèse du fructose-1,6-diphosphate (adding another phosphate) (étape 3)
Enzyme:** PFK-1**
Input: fructose 6 phosphate
Output: fructose 1,6 di phosphate - Synthèse du pyruvate et 2 ATP (étape 10)
Enzyme: Pyruvate Kinase
Output: pyruvate + 2 ATP
Which of the steps in glycolysis is the key point of control
- Synthèse du fructose-1,6-diphosphate (adding another phosphate) (étape 3)
Regulation of glycolysis:
Exam quesiton
Concentration de glucose (stimulation par le substrat)
Concentration d’ATP
* Inhibition par [ATP] élevées:
Insuline stimule la glycolyse
Fructose-2,6-diphosphate stimule glycolyse (Exam quesiton)
