Term
| What is GLUT 2 and what is its role? |
|
Definition
| It is a low-affinity transporter of glucose in hepatocytes and pancreatic cells. Excess glucose in blood will be taken up and stored. |
|
|
Term
| What is GLUT 4 and what is its role? |
|
Definition
| It is a glucose transporter in adipose and muscle tissues. It responds to glucose concentration in blood. Insulin acts to increase the number of transporters at the cell surface to promote glucose uptake. |
|
|
Term
|
Definition
- the breakdown of glucose in two pyruvate molecules
- occurs in cytoplasm
|
|
|
Term
|
Definition
glucose → glucose-6-phosphate
Uses ATP
Inhibited by G-6-P
Found throughout tissues
Phosphorylation of glucose prevents it from being transported back out of cell becaue GLUT transporters only work with glucose. |
|
|
Term
|
Definition
glucose → glucose-6-phosphate
Uses ATP
Induced by insulin
Found in liver cells and β-islet cells in pancreas
Phosphorylation of glucose prevents it from being transported back out of cell becaue GLUT transporters only work with glucose. |
|
|
Term
|
Definition
phosphofructokinase-1
fructose-6-phosphate → fructose 1,6-bisphosphate
- Uses ATP
- Committed/Control step in glycolysis
- Inhibited by ATP and citrate
- Activated by AMP
PFK-2 activated by insulin and inhibited by glucagon so PFK-1 indirectly activated and inhibited:
PFK-2 converts fructose-6-P into fructose-2,6-bisphosphate. Fructose-2,6-bisphosphate activates PFK-1. |
|
|
Term
| Glyceraldehyde-3-phosphate dehydrogenase |
|
Definition
glyceraldehyde-3-phosphate ↔ 1,3-bisphosphoglycerate
Uses NAD+ as oxidizing agent (can be used by e- transport chain)
Adds inorganic phosphate (Pi) |
|
|
Term
| 3-phosphoglycerate kinase |
|
Definition
1,3-bisphosphoglycerate ↔ 3-phosphoglycerate
Transfers phosphate to ADP
Produces ATP
substrate level phosphorylation |
|
|
Term
| What is substrate level phosphorylation? |
|
Definition
| phosphorylation that is not dependent on oxygen and is the only menas of ATP generation in anaerobic tissue |
|
|
Term
|
Definition
phosphoenolpyruvate → pyruvate
substrate level phosphorylation of ADP by taking phosphate from PEP
Produces ATP
Activated by fructose-1,6-bisphosphate from PFK-1 rxn |
|
|
Term
|
Definition
pyruvate ↔ lactate
- catalyzes fermentation
- NADH is oxidized to NAD+ replenishing it for the G-3-P DHase rxn.
- Occurs during strenuous exercise
|
|
|
Term
| What are the points in glycolysis that generate ATP? |
|
Definition
3-phosphoglycerate kinase
1,3-bisphosphoglycerate → phosphoglycerate
pyruvate kinase
phosphoenolpyruvate → pyruvate
|
|
|
Term
| What intermediate of glycolysis crosses over with another pathway? |
|
Definition
| Dihydroxyacetone phosphate (DHAP), produced from fructose 1,6-bisphosphate, can be isomerized to glycerol 3-phosphate which can be converted to glycerol, the backbone of triacylglycerols |
|
|
Term
| What are the irreversible enzymes of glycolysis? |
|
Definition
- glucokinase/hexokinase
- phosphofructokinase-1 (PFK-1)
- pyruvate kinase
|
|
|
Term
| What are two other monosaccharides used by cells and how are they used? |
|
Definition
Galactose - converted to glucose-1-phosphate
Fructose - fructose-1-phosphate cleaved into dihydroxyacetone phosphate (DHAP) and glyceraldehyde. Glyceraldehyde can be turned into G-3-P |
|
|
Term
|
Definition
pyruvate → acetyl-CoA
- NAD+ used as oxidizing agent
- CO2 produced
- Coenzymes: thiamine pyrophosphate, lipoic acid, CoA, FAD and NAD+
- Inhibited by Acetyl-CoA, ATP, ↑NADH/NAD
|
|
|
Term
|
Definition
The synthesis of glycogen.
- Starts with core protein glycogenin
- Glucose is attached to glycogenin
- Glycogen synthase elongates glucose chains connected to granule
- Branching enzyme introduces α-1,6 branches
|
|
|
Term
|
Definition
The breakdown of glycogen.
- Glycogen phosphorylase breaks α-1,4 glycosidic bonds releasing glucose
- Debranching enzyme breaks down branching of glycogen
|
|
|
Term
| What are the enzymes unique to gluconeogenesis? |
|
Definition
- Pyruvate carboxylase
- PEP carboxykinase
- Fructose-1,6-bisphosphate
- Glucose-6-phosphatase
|
|
|
Term
|
Definition
pyruvate → oxaloacetate
- Uses ATP and CO2
- mitochondrial enzyme
- Activated by acetyl-CoA
|
|
|
Term
| phosphoenolpyruvate carboxykinase |
|
Definition
oxaloacetate → phosphoenolpyruvate
- cytoplasm
- Uses GTP
- Activated by glucagon and cortisol (they generally act to raise blood sugar levels)
|
|
|
Term
| Fructose-1,6-Bisphosphatase |
|
Definition
fructose-1,6-bisphosphate → fructose-6-phosphate
- Produces one phosphate
- Activated by ATP
- Inhibited by AMP and fructose-2,6-bisphosphate
|
|
|
Term
|
Definition
glucose-6-phosphate → glucose
- Removes one phosphate
- Found only in lumen of ER in liver cells
|
|
|
Term
| Pentose phosphate pathway |
|
Definition
aka hexose monophosphate shunt, has two major functions
- production of NADPH
- Serves as a source of ribose 5-phosphate for nucleotide synthesis
|
|
|
Term
|
Definition
NAD+ is oxidizing agent (accepts electrons)
NADPH is reducing agent (donates electrons) |
|
|
Term
|
Definition
| a reducing agent that can help reverse free radical formatino before damage is done to the cell |
|
|
