Glycolysis 2 Flashcards
What does there need to be a continual supply of in order for glycolysis to continue?
NAD+
How are apoenzymes activated?
By binding of coenzyme or cofactor to enzyme
How is a holoenzyme formed?
When associated cofactor/ coenzyme binds to the enzymes active site
Does the coenzyme have to bind before or after the substrate?
before
Do coenzymes bind tightly or loosly and why?
Relatively tightly so the particular group to be transferred is properly orientated to allow catalysis to occur
Do coenzymes need to be regenerated?
Yes
Once bound to a chemical group what happens to the coenzyme
The coenzymes structure changes
What are the 3 steps to how Glyceraldehyde-3-phosphate dehydrogenase works
1- Formation of covalent thioester bond between substrate and enzyme
2-Oxidation of the thioester bond to form thioester bond using NAD+ to perform the oxidation
3- cleavage of the thioester bond supplies the energy to drive the endergonic phosphorylation reaction. The product, a phosphoanhydride is realised from the enzyme
Hydrolysis of a thioester bond is exergonic or endergonic?
Exergonic
What is the fate of pyruvate in aerobic conditions?
Continual Supply of NAD+ by oxidation of NADH by the ETC
Pyruvate can enter mitochondria and be consumed by TCA cycle to generate more NADH
What is the fate of pyruvate in anaerobic condition?
NAD+ is generated by conversion of pyruvate to lactate. ALL of pyruvate needed for this
RBC only use lactic acid pathway not O2 - why and how is this useful?
RBS have no mitochondria and this spares o2 they carry to deliver to other cells
What is the equation for pyruvate to lactate?
2 pyruvate ( from glycolysis) -> 2 lactate with 2NADH + 2H+ to produce 2 NAD+
What is the equation for pyruvate to alcohol?
2 Pyruvate-> 2CO2 + 2 Acetaldehyde with pyruvate decarboxylase
2 Acetaldehyde-> 2 ethanol via alcohol dehydrogenase and 2 NADH to 2 NAD+
Under anaerobic conditions how many ATP are produced and why?
2 ATP are produced for every glucose molecule that is converted to lactate or alcohol.
NADH is recycled and not used to make more ATP.
In both prokaryotic and eukaryotic organisms where does Glycolysis occur?
cytoplasm
In both prokaryotic and eukaryotic organisms where does the TCA cycle occur?
Prokaryotic-cytoplasm
Eukaryotic-mitochondria
In both prokaryotic and eukaryotic organisms where does the ETC occur?
Prokaryotic- cell membrane
Eukaryotic-mitochondrial membrane
In both prokaryotic and eukaryotic organisms where does fermentation occur?
cytoplasm
There is no specific mitochondrial NADH transporters
cool
Name the full equation from pyruvate to Acetyl-CoA
Pyruvate -> Pyruvate dehydrogenase complex, NAD+ CoA-SH to NADH CO2 AcetylCo-A
What does Coenzyme A stand for?
“activation of acetate“
What are the 3 steps of pyruvate oxidation steps
Step 1. A carboxyl group is snipped off of pyruvate and released as a molecule of carbon dioxide, leaving behind a two-carbon molecule (acetate).
Step 2. The two-carbon molecule from step 1 is oxidized, and the electrons lost in the oxidation are picked up by NAD+ to form NADH.
Step 3. The oxidized two-carbon molecule—an acetyl group, highlighted in green—is attached to Coenzyme A (CoA), an organic molecule derived from vitamin B5, to form acetyl CoA. Acetyl CoA is sometimes called a carrier molecule, and its job here is to carry the acetyl group to the citric acid cycle.
2c into TCA
Summarise pyruvate oxidation
Two molecules of pyruvate are converted into two molecules of acetyl CoA.
Two carbons are released as carbon dioxide—out of the six originally present in glucose.
2 NADH are generated from NAD+.
