Biochemistry 4 carbohydrates Flashcards
Liver b2
gluconeogenesis & glycogenolysis
liver a1
glycogenolysis
pancreas b2
insulin secretion
pancreas a2
inhibit insulin release
adipose B3
lipolysis
adipose a2
inhibit lipolysis
skm B2
glycogenolysis
Energy is obtained from fuel by oxidizing it to?
CO2 & H2O
Fuel for energy?
carbohydrates, fat, and protein in the diet
Catabolism is?
those reactions that transform fuel into cellular energy
breaking down fuel into ATP
catabolic hormone?
glucagon
Catabolism three stages?
- Hydrolysis of complex molecules to their component building blocks
- Conversion of building blocks to acetyl CoA (precursor that enters TCA cycle)
• Acetyl CoA is the meeting point for all different types of molecule pathways (fat, protein) - Oxidation of acetyl CoA; oxidative phosphorylation ETC
anabolic hormone?
Insulin
Major fuel source for the brain and RBC?
glucose
major site for glucose metabolism?
liver
first step of glucose metabolism?
glycolysis
the hub of carbohydrate metabolism?
Glycolysis
-all sugars can ultimately be converted to glucose
Aerobic glycolysis takes place in cells with?
cells with a mitochondria
Anaerobic glycolysis takes place in? 2
cells with no mitochondria ie RBC,
hypoxia
where does glycolysis take place?
cytosol
Anaerobic glycolysis occurs in? 7 R T KM L C L
cells that are poorly vascularized or w/o mitochondria – RBC, testes, kidney medulla, lens, cornea, & leukocytes
What enzyme produces lactate from pyruvate?
lactate dehydrogenase
(NADH oxidized to NAD+) – reversible
What cause lactate to be formed during exercise ?
an increase in NADH production ↑ NADH/NAD+ ratio ETC can’t keep up, favors reduction of pyruvate to lactate
Lactate build up in muscles ?
decrease in pH and muscle cramps
GLUT 1
3
Blood RBC
Baby/fetus
Blood Brain Barrier
GLUT 2
3
Kidney
liver
pancreas
GLUT 3
3
Placenta
Neuron
Kidney
GLUT 4
Muscle
adipose
Which GLUT requires Insulin?
GLUT 4
Glucose contains how many carbon?
6
Glucose enters the cell and splits into?
two 3 carbon molecules that both go through glycolysis making 2 pyruvate
The heart and liver have less NADH/NAD compared to muscles, lactate from blood is oxidized to
_______through________or in the __________
pyruvate through gluconeogenesis or in the TCA cycle
After an MI heart cells releases Lactate dehydrogenase into circulation, what can be a biomarker for heart damage?
H:heart isoform ratio higher than M:SKM/liver -usually rises 2-5 days post MI
Elevated lactate post cardio collapse ie, MI, PE, shock, etc, leads to _________ from failure to provide adequate _________ (impaired _________ _________)
lactic acidosis from failure to provide adequate 02 (impaired oxidative phosphorylation)
Lactic acidosis leads to decreased_____ and have to rely on________
ATP synthesis
anaerobic metabolism
Lactic acidosis leads to increased O2 debt that requires excess O2 to recover from inadequate O2. What lab needs to be monitored?
serial lactate levels to measure severity of shock and recovery
Most energy comes from the end products of pyruvate or lactate in?
the citric acid cycle
aka TCA cycle, Krebs cycle
Define glycolysis in simple terms
Glucose 6 P makes pyruvate through a series of chemical reactions.
Pyruvate can then be converted to acetyl CoA that enters the citric acid cycle (TCA, Kreb) in the mitochondria
What two things phosphorylate glucose into Glucose 6 phosphate?
Hexokinase in a cells
Glucokinase: in pancreas, acts as a sensor to increase insulin secretion, most active after meal
The 3 irreversible steps of glycolysis
- phosphorylation of Glucose to
glucose 6 phosphate by hexokinase - phosphorylation Fructose 6 phosphate to fructose 1, 6 bisphosphate by phosphofructokinase 1
- Phosphoenolpyruvate PEP to pyruvate by pyruvate kinase
What leads to the gluconeogenesis pathway? _______ ______ inactivation by ______
pyruvate kinase inactivation by PKA
Pyruvate kinase deficiency leads to?
mutant
genetically mutant pyruvate kinase leads to hemolytic anemia
Pyruvate kinase deficiency MOA?
-Second leading cause of
- RBC’s do not have mitochondria, so they rely on glycolysis for ATP – decrease ATP results in alterations in shape and phagocytosis by the spleen
- Second leading cause of enzyme deficiency hemolytic anemia
Glycolysis is regulated by what 2 major needs of the cell?
ATP (if we have plenty, inhibits glycolysis)
Building blocks for synthetic reactions
Name the Enzymes catalyzing irreversible reactions that are also sites of control.
The amount of enzyme regulated by?
Hexokinase, phosphofructokinase 1, and pyruvate kinase
transcription
Well-fed state ______results in gene _______ and _______ synthesis
insulin results in gene transcription and enzyme synthesis
Fasting or diabetes high ______ and low _______ leads to ________ enzyme synthesis
high glucagon and low insulin leads to decreased enzyme synthesis
TCA cycle is final pathway where _________metabolism of ________, _______, and _______converge
C
A
F
final pathway where oxidative metabolism of carbohydrate, amino acids, and fatty acids converge
glucose synthesis from non carbohydrate precursors
gluconeogenesis
the breakdown of glycogen to glucose-1-phosphate and glycogen
glycogenolysis
Anaerobic glycolysis In Gl and liver
in NADH/NAD+ ratio compared to muscles – oxidize lactate from blood to pyruvate through gluconeogenesis or in the citric acid cycle
