Respiration A2 Flashcards
What coenzymes are involved in Glycolysis?
NAD, FAD and Coenzyme a
What do NAD and FAD do?
they carry hydrogen ions take from the reactant, allowing the reactant to be reduced
what are the two stages of glycolysis?
Phosphorylation and oxidation
What are the start and end products of the phosphorylation stage of glycolysis?
Glucose——-two pyruvate molecules
How does phosphorylation turn Glucose to triose phosphate?
Clue- hexose bisphosphate
The initial glucose molecule is bonded to two phosphate molecule to create a more unstable six carbon molecule called hexose bisphosphate. (These two phosphate molecules are taken from hydrolysis of two ATP. This hexose bisphosphate is then split into two (as if straight down the middle) into two triose phosphate molecules (each has 3 carbons).
Why do we change glucose to hexose bisphosphate in phosphorylation?
As hexose bisphosphate is more reactive than glucose, so can be split into the triose phosphate molecules more easily.
What are the input and output products in the oxidation phase of glucose?
Input- 2 triose phosphate
output- 2 pyruvate molecules
How are coenzymes involved in the oxidation phase of glycolysis?
the two triose phosphate molecules are dehydrogenated (oxidised) and the electrons/H+ ions are taken on by 2 NAD enzymes, leaving two reduced NAD and two triose phosphate molecules.
What happens in the oxidation phase of glycolysis?
First, the TP molecules are dehydrogenated
then, two of the phosphate groups from the TP molecules are then combined with ADP to each create two ATP molecules (one phosphate from each TP molecule is used to create two ATP) therefore creating 4 ATP molecules. The TP that the phosphate was removed from has now become Pyruvate, so we are finally left with two pyruvate molecules (which each have 3 carbons).
What are the end products of glycolysis?
2 pyruvate molecules, 2 reduced NAD and 2 net ATP. (we subtract the two ATP used in the phosphorylation phase from the 4 produced in the oxidation phase).
Where does The Link Reaction occur?
What does this mean in terms of transport of the products from glycolysis?
It takes place in the mitochondrial matrix
It means that the products from Glycolysis- the two pyruvate- have to be transported from the cytoplasm, across the mitochondrial membrane and into the matrix via active transport.
What is the aim of the link reaction?
To convert one 3-carbon pyruvate molecule into one 2-carbon acetate, which will then be used in the krebs cycle.
How can 3-carbon pyruvate become 2-carbon acetate in the Link reaction?
The pyruvate must lose one carboxyl group and on hydrogen atom
What do you call it when a compound loses a hydrogen atom/ion?
dehydrogenation
What do you call it when a compound loses a carbon atom/ion?
decarboxylation
How are coenzymes used in the link reaction?
Remember the ending?
When the pyruvate is dehydrogenated to form acetate, the hydrogen is taken up by an NAD molecule (the NAD becomes reduced).
After the acetate is formed, it combines with coenzyme a temporarily, in order to stabilise it, therefore becoming Acetyl CoA.
What happens to the carboxyl group removed from Pyruvate in the link reaction?
How does this relate to the original respiration equation
(Oxygen + Glucose →→→ CO2 and Water)
The carboxyl is combined with two oxygen to make CO2.
This is one of the waste products produced in respiration. The waste product of water is produced in oxidative phosphorylation.
What is the equation for the link reaction?
Pyruvate + NAD + Coenzyme A →→→ Acetyl CoA + Reduced NAD + Carbon Dioxide
What are the desired products of the Krebs Cycle?
Reduced NAD, reduced FAD and ATP.
These are needed for oxidative phosphorylation (Oxaloacetate is also produced in order to restart the cycle)
What are the waste products of the Krebs Cycle?
Carbon Dioxide
What enzyme is used in the Krebs cycle to aid the change of a 4 carbon compound to Oxaloacetate?
Isomerase
Where does oxidative phosphorylation take place?
In the christae of the mitochondria
what reactant and product are used/produced in oxidative phosphorylation?
Oxygen- reactant
Water- product
what products from EACH of the previous stages of respiration are used in oxidative phosphorylation?
Glycolysis- 2 reduced NAD
Link Reaction- 2 reduced NAD
Krebs Cycle- 6 reduced NAD and two reduced FAD