Glycolysis Flashcards
Hexose ring has how many carbons?
Six
Pentose ring has how many carbons?
five
What are some 6 carbon Hexose rings?
First, theyre referred to as monosaccharides. Examples include : glucose, fructose, mannose, galactose
What are some 5 carbon pentose ring examples?
Example: Ribose which is in DNA, RNA and NADH
Most sugars in mammals are what kind of sugars?
D-sugars!
Enantiomers are?
mirror images
Disaccharides are used for what and composed of?
used for storage and are composed of two sugars
Lactose :
Galactose and Glucose
Sucrose :
Fructose and Glucose
Polysaccharides are used for ?
Structural sugars and for storage. 2 + sugars.
Glycogen is found in and made of?
Animals, and made of Glucose alpha linked
Starch is found in and made of?
Plants, and made of glucose alpha linked
dextran is found in and made of?
yeast, and alpha linked
Cellulose is found in and composed of?
plants, and glucose is beta linked
Chitin is found in and composed of?
insects, crustacean, exoskeleton, and its composed of N-Acetyl Glucosamine Beta linked.
Fxn of glycolysis?
to convert glucose to three carbon compounds with the formation of ATP
Glycolysis occurs in which cells and the enzymes are located in?
ALL CELLS in the body and in the cytosol.
How many rxns is glycolysis made up of? and what is glucose converted into?
10 rxns, glucose is converted into pyruvate!
The intial req of ATP in glycolysis is? and the NET production is?
intial req is 2 ATP, and net total production is 2 ATP!
What is the oxidative step in glycolysis where NAD+ is reduced to NADH?
Glyceraldehyde 3 phosphate to 1,3 biphosphoglycerate
How are NAD+ replenished?
Through aerobic respiration or anerobic fermentation : Lactate dehydrogenase
two substrate level phosphorylations. What are they?
phosphoglycerate kinase and pyruvate kinase
Formation of ATP from 1,3 biphosphoglycerate. Enzyme involved? Substrate? Products?
Enzyme : Phosphoglycerate kinase Substrate : ADP, 1,3 biphosphoglycerate Product: 3 phosphoglycerate, ATP
Formation of ATP from phosphoenolpyruvate. Enzyme? Substrate? Products?
Substrate : Phosphoenolpurvate, ADP Enzyme : Pyruvate Kinase Products : ATP, Pyruvate
Irreversible rxns :
Phosphofructokinase Hexokinase Pyruvate Kinase
How does Phosphofructokinase responds to changes in ATP. High ATP does what?
Inhibit phosphofructokinase
High lactate, High H+ does what to phosphofructokinase?
Inhibit
Alternate fuels available to phospfructokinase? high citrate?
Inhibit
Insulin/glucagon ration
High fructose 2,6 biphosphate levels on phosphofructokinase?
activate
Fructose 2,6 biphosphate is?
an allosteric activator on phosphofructokinase!
Pyruvate Kinase has an allosteric regulator
What are they?
Fructose 1,6 Biphosphate –>
it upregulates the dephosphorylation of pyruvate kinase
Phosphorylated pyruvate kinase ?
inactive
Dephosphorylated pyruvate kinase?
active
High Blood Sugar
up regulate dephosphorylated pyruvate kinase
low Blood Sugar
up regulate phosphorylated pyruvate kinase
Glycolysis is critical for what body parts?
brain and erythrocytes metabolism and excercising muscle.
Phosphofructokinase is regulate by?
fructose 2, 6 biphosphate and is the rate limiting step
pyruvate kinase has secondary regulation? how?
it undergoes phosphorylation-dephosphorylation
glucose homeostasis relies critically on detection of variations in blood glucose concentrations by what cells and for a release of what?
pacreatic beta cells and the release of the appropriate amount of insulin.
whats the rate controlling step in glucose stimulated insulin secretion ?
the glucokinase!
glucokinase mutation causes early onset of?
type 2 diabetes
Glut 2 has what affinity for glucose?
LOW affinity, thus needs ALOT of glucose to be recognized
in Pancreas, where are hormones produced?
Islets of Langerhans!
Elevated Blood glucose trips an ATP dependent switch in beta cells leading to ?
insulin release
How is insulin released?
A rise in the [ATP]/[ADP] ratio in the cell serves to inhibit the
ATP-sensitive K+ channels (KATP) at the cell surface
–> causing the membrane to depolarize
Opening of voltage-dependent Ca2+ channels (VDCC) results in a rise in intracellular [Ca2+]
–> stimulates insulin secretion
Type 2 Diabetes :
mutation in glucokinase thus leading to decreased levels of insulin release.
Treatment of type 2 diabetes?
Sulfoyfurea and Repaglinide
This blocks the K channels regardless of glucose levels
and thus
depolarizes the membrane and turns on Calcium voltage channels signaling for insulin to be released
What causes insulin to rise before we eat food?
from vagus nerve activation by the brain in response to input from sensory organs, including those of the oral cavity and the visual and olfactory systems
Acetylcholine (ACh) is released from intrapancreatic nerve endings and stimulates insulin secretion
After we eat, insulin rises how?
Glucose is high
the vagus nerve stimulates AcH release of second messengers
and thats what triggers the release of insulin
Recycling the carbon skeleton anaerobically
What happens to lactate in RBC or muscles?
Lactate is converted to glucose through the Cori cycle by
being shuttled back into the liver via gluconeogenesis
Recycling of the carbon skeleton in the muscle cells to the liver?
Alanine Cycle shuttled into the liver
this is better because not acidic like lactate
its converted back into glycolysis via gluconeogenesis
pyruvate kinase deficiency
Autosomal dominant or recessive disease,
resulting in spiny red blood cells (echinocytes)
- Second most common cause of enzyme deficient hemolytic anemia
Cancer
High glycolytic rate up to 200 fold higher than normal cells
- overexpression of plasma membrane glucose transporters of the GLUT family
- allowing for higher glucose uptake rates
Why is PET and imagining used in oncology?
Bc of the high glycolytic rate of tumor cells thus using the uptake of 2-18F deoxyglucose FDG substrate.
A patient comes into the ER and has a __________________ deficiency. This can lead to chronic hemolytic anemia and deformed spiny red blood cells, called “echinocytes”.
Glycokinase
PFK
Phosphoglycerate Kinase
Pyruvate Kinase
Pyruvate Kinase
In the Alanine cycle, Alanine is recycled from muscle cells to the kidney.
True
False
False
to the LIVER
Which of the following is NOT a hexose?
Glucose
Fructose
Ribose
Galactose
Ribose
The following are polysaccharides that are (glucose)n alpha-linked EXCEPT:
Glycogen
Cellulose
Starch
Dextran
Cellulose
Glycolysis occurs in all cells of the body and enzymes are located exclusively in the ________.
Inner membrane
Matrix
Cytosol
2 answers are correct.
Cytosol
There is an initial requirement for ATP but glycolysis results in the net production of ______ ATP.
4
3
1
2
2
What occurs in step 7 of glycolysis during substrate-level phosphorylation?
A. 1,3 Biphosphoglycerate catalyzed to 3 phosphoglycerate by phosphoglycerate kinase
B. 1,3 Biphosphoglycerate catalyzed to phosphoenolpyruvate by phosphoglycerate kinase
C. phosphoenolpyruvate catalyzed to pyruvate by phosphoglycerate kinase
D. phosphoenolpyruvate catalyzed to pyruvate by pyruvate kinase
A. 1,3 Biphosphoglycerate catalyzed to 3 phosphoglycerate by phosphoglycerate kinase
What are the three irreversible reactions in glycolysis?
A. Glucokinase, phosphofructokinase, pyruvate kinase
B. Hexokinase, phosphofructokinase, pyruvate kinase
C. Hexokinase, phosphofructokinase, phosphoglycerate kinase
D. Glucokinase, pyruvate kinase, phosphofructokinase
B. Hexokinase, phosphofructokinase, pyruvate kinase
All of these inhibit PFK EXCEPT:
High ATP levels
High lactate levels
High citrate levels
High fructose 2,6-bisphosphate levels
High fructose 2,6-bisphosphate levels
Under anaerobic conditions, _______ is regenerated by conversion of pyruvate to lactate.
NADH2
NAD+
ADP
ATP
NAD+
Glucose uptake by beta cells is catalyzed by a transporter called ________.
GLUT2
GLUT5
UCP2
VDCC
GLUT2
What enzyme catalyzes the rate-controlling step in glucose-stimulated insulin secretion of pancreatic beta cells?
Hexokinase
PFK
Glucokinase
Pyruvate kinase
Glucokinase
A rise in [ATP/ADP] ratio in the cell serves to inhibit/close the _________ causing the membrane to ___________.
ATP-sensitive K+ channels; depolarize
ATP-sensitive K+ channels; polarize
Voltage dependent Ca2+ channels; depolarize
Voltage dependent Ca2+ channels; polarize
ATP-sensitive K+ channels; depolarize
Mechanisms by __________ stimulates insulin secretion in the preabsorptive and absorptive phase in food intake.
Choline
Acetylalcohol
Acetylcholine
N-acetyl glucosamine
Acetylcholine
Lactate is recycled from erythrocytes (or muscles cells) to the liver in the Cori Cycle.
True
False
True