Exam1 Flashcards
Glucose transporter (SGLT) Sodium dependent glucose transport
SLC gene 5
Symporter
Uses Na to go down its gradients while glucose goes against. (secondary active transport)
GLUTX uniporters
SLC gene 2
Glucose transported bidirectionally down gradient
GLUT 1 (Tissue Location)
Brain, Ethrocytes, colon, placenta kidney
(Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport)
GLUT 1 (Function)
Constitutively and widely
expressed, highest glucose
affinity(lowest K m) and basal
glucose uptake
(Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport)
GLUT 1 (Deficency)
Epileptic encephalopatny
movement disorder, development delats, immature tight junctions
(Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport)
GLUT 2 (Location)
Liver, Pancreatic β cells, Small intestines, kidney
tubular cells
Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport
GLUT 2 (Function)
Rapid glucose uptake and
release, Lower V max than GLUT
1/3, High K
Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport
GLUT 2 Deficiency
Bickel syndrome, hepatomegaly , Ricketts, hepatomegaly, glucose, galactose, fructose intolerance , hypoglycemia
Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport
GLUT 3 (Location)
Brain, Kidney, Placenta
Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport
GLUT 3 (Function)
Similar to GLUT 1
Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport
GLUT 5 (Location)
Small intestines
Facilitated Bidirectional
Non-Insulin-Dependent
Glucose Transport
GLUT 5 (Function)
Fructose uptake
Facilitated
Bidirectional Insulin-
Dependent Glucose
Transport
GLUT 4 (Location)
Adipose tissues, Heart and skeletal muscle
Facilitated
Bidirectional Insulin-
Dependent Glucose
Transport
GLUT 4 (Function)
Insulin-induced/regulated
glucose uptake
Sodium-Dependent
Unidirectional
Glucose Transport
SGLT-1 (Location)
Small intestines and kidney tubules (apical
surfaces)
Sodium-Dependent
Unidirectional
Glucose Transport
SGLT-1 (Function)
SGLT1 accepts glucose and
galactose and is a 2 Na+:1
monosaccharide cotransporter.
Sodium-Dependent
Unidirectional
Glucose Transport
SGLT-1 (Deficency)
-Glucose Galactose malabsorption
-Newborn diarrhea
- Stool acidic , H+ brain
Sodium-Dependent
Unidirectional
Glucose Transport
SGLT-2 (Location)
Kidney tubules (apical surface
Sodium-Dependent
Unidirectional
Glucose Transport
SGLT-2 (Function)
SGLT2 accepts glucose (not
galactose) and is a 1 Na+:1
monosaccharide cotransporter;
it moves the bulk of filtered
glucose.
Sodium-Dependent
Unidirectional
Glucose Transport
SGLT-2 (Deficiency)
Renal glucosuria
hypovolemia
hyperaminoaciduria
It is a target of a class of oral hypoglycemic
agents including canagliflozin, dapagliflozin, and
empagliflozin
* Possible gout treatment
Nucleus
(Brain) Control center of cell
Mitochondria
(Powerhouse) Provides Energy
Golgi Apparatus
sort, packages transports protein
Endoplasmic Reticulum
Protein Synthesis
Ribosomes
Protein Synthesis
Lysosomes
Lipid degradation breakdown
HEXOKINASE
- Expressed by most tissues
- Not induced by insulin
- Lower Km (high glucose affinity)
- Lower Vmax (low glucose
capacity) - Inhibited by glucose 6-phosphate
GLUCOKINASE
- Present on liver, small intestines
and pancreatic β cells - Induced by insulin
- Higher Km (low glucose affinity)
- Higher Vmax (high glucose
capacity) - Inhibited by Glucokinase
regulatory protein via fructose
6-phosphate
Phosphofructokinase
Deficiency
inability to utilize free or glycogen derived
glucose as a fuel source with the accumulation of
glycogen.
* (Myophosphorylase
deficiency) – muscle cramps, exercise intolerance,
rhabdomyolysis, , hemolytic anemia (not present in
McArdle’s) and hyperuricemia – floppy babies.
*A forearm ischemic exercise test shows a flat lactate
curve and a normal increase in ammonia.
*Management : a high fat, high protein, low
carbohydrate diet and rest (avoiding strenuous activity)
Pyruvate kinase Deficiency
*Most common glycolytic enzymopathy. Commonly autosomal recessive
disorder that causes both acute and chronic hemolysis
*Increased 2,3-bisphosphoglycerate(BPG or DPG) and lower than
normal O2 affinity of Hb
*Reduced ATP production in RBCs due to its deficiency causes them
to become abnormally shaped and easily destroyed in the spleen.
They form echinocytes – “Burr cells” that look like a hedgehog with
evenly spaced thorny spikes on the surface.
*Also loss Na+/K+ pump activity causes cell swelling, membrane
rigidity, osmotic fragility and lysis
*This condition is characterized by an absence of Heinz bodies
(inclusion bodies)
*May require partial splenectomy to reduce the incidence of hemolysis
IRREVERSIBLE STEPS
IN GLYCOLYSIS
Phosphofructokinase (-25 KJ/
mol)
* Glucokinase (-27 KJ/mol)
* Pyruvate kinase (-14 KJ/mol)
* All have DG too large and
negative to simply reverse
Recall Hexokinase catalyzes:
Glucose + ATP -> G6P + ADP
G6P + ADP -> Glucose + ATP
Gluconeogenesis: Energy
Requirement
The vast amount of energy required to drive
gluconeogenic reactions is derived from fatty acid
oxidation – therefore impaired fatty acid oxidation is
often characterized by failure of gluconeogenesis
leading to hypoglycemia.
* From pyruvate, 3 moles of ATP are consumed by the;
–Pyruvate carboxylase reaction
–PEPCK reaction
–PGK reaction
And since 2 pyruvates are used to produce 1 mole of
glucose, a total of 6 moles of ATP is used.
* From glycerol, 1 mole of ATP is used by glycerol
kinase and since 2 moles of glycerol yield 1 mole of
glucose, the total ATP involved is 2
* Glycerol is more energy efficient!
FADH2 from Riboflavin(Vit B2)
Oxidized- FAD
Reduced- FADH2
Sources= milk and dairy
Co-Factor = Succinate dehydrogenase
NADH from Niacin(Vit B3)
Useful for NAD+, NADH,
- anti-hyperlipidemic agent, providing ADP-ribosylation
of proteins for gene regulation, apoptosis and signaling
Hartnup disease
carcinoid syndrome
*Deficiency – Pellagra
Coenzyme A
H2O soluble vitamin
essential life
Thiamine Pyrophosphate TPP
carbon on thiamine ring
aldehyde transfer
alcoholism
uncooked silkworm/fish
= deficiency
-Lipoic acid (Lipoamide in
proteins)
provide a reactive disulfide or sulfhydryly group that
can participate in redox reactions
E1 pyruvate
dehydrogenase subunit
TPP
E2 dihydrolipoyl transacetylase
lipoamide
E3
dihydrolipoyl dehydrogenase
FAD
The pyruvate dehydrogenase reaction can be
broken down into five distinct catalytic steps:
- Decarboxylation
- Transfer of the acetyl group to lipoamide
- Formation of acetyl-CoA
- Redox reaction to form FADH2
- Redox reaction to form NADH
