Respiration Flashcards
What is cellular respiration?
The process by which the energy contained in organic molecules is made available for all of the active processes in a cell
What is the usual substate in respiration?
(The organic substance that releases energy) is glucose but fats, amino acids and other substates can be used if necessary
Short term, how is the released energy from respiration stored?
In ATP
In what two ways can respiration occur?
Aerobically or anaerobically
What is aerobic respiration?
With oxygen
What is anaerobic respiration?
Without oxygen
Per glucose molecule how much more ATP is produced aerobically than anaerobically?
19x
What are the four stages of respiration?
Glycolysis, the link reaction, the Kreb’s cycle and the electron transfer chain
What is the respiratory quotient?
The ratio of carbon dioxide produced to oxygen consumed per time unit by an organism
What is the formula for the respiratory quotient?
RQ= volume of carbon dioxide produced / volume of oxygen produced
What is the RQ value of glucose?
1
What is the RQ value of amino acids?
0.9
What is the RQ value of a triglyceride?
0.7
Where does glycolysis take place?
In the cytoplasm
Where does the link reaction take place?
In the matrix of the mitochondria
Where does the Krebs cycle take place?
The matrix of the mitochondria
Where does the electron transfer chain take place?
In the crista of the inner membrane of the mitochondria
Is oxyen needed for glycolysis?
No
Is oxygen needed for the link reaction?
Yes
Is oxygen needed for the Krebs cycle?
Yes
Is oxygen needed for the electron transfer chain?
Yes
What is the net ATP production per glucose molecule in glycolysis?
2
What is the net ATP production per glucose molecule in the link reaction?
0
What is the net ATP production per glucose molecule in the Krebs cycle?
2
What is the net ATP production per glucose molecule in the electron transfer chain?
34
Which stage of respiration yields the most ATP per glucose molecule?
The electron transfer chain
When does anaerobic respiration take place?
When there is no available oxygen
Why cant the Krebs cycle or the electron transfer chain take place without oxygen?
Without oxygen there is no where to dispose of the hydrogen
Which part of respiration can still occur in anaerobic conditions?
Glycolysis
What is produced from anaerobic respiration?
2 ATP molecules and reduced NAD
In order for glycolysis to continue what must happen to the reduced NAD
Reduced NAD must be reoxidised (hydrogen must be removed)
In aerobic respiration how is reduced NAS normally reoxidised?
Using oxygen
How does yeast respire anaerobically?
Pyruvate is decarboxylased to produce ethanal. Ethanal then accepts the hydrogen from NAD and forms ethanol. This releases the NAD to be reused in glycolysis.
What is the anaerobic respiration of yeast called?
Alcoholic fermentation
How do mammals respire anaerobically?
The pyruvate accepts the hydrogen from NAD and is reduced to lactate. The NAD is then available for further use in glycolysis. If oxygen later becomes available the lactate is reoxidised
In alcoholic fermentation what happens to pyruvate?
It is decarboxylased
What is pyruvate decarboxylased to produce?
Ethanal
In alcoholic fermentation What happens to ethanal?
It accepts the hydrogen from NAD to form ethanol
In alcoholic fermentation What happens to the reoxidised NAD?
It is released to be reused in glycolysis
In mammalian anaerobic respiration, what happens to the pyruvate?
It accepts the hydrogen from reduced NAD
In mammalian anaerobic respiration, what is pyruvate reduced to?
Lactate
In mammalian anaerobic respiration, What happens to the reoxidised NAD?
It is available for further use in glycolysis
In mammalian anaerobic respiration, What happens if oxygen later becomes available?
Lactate is reoxidised
How many molecules of ATP does anaerobic respiration produce?
2
In brief, what happens in glycolysis?
Glucose is converted to pyruvic acid. Hydrogen is removed and is passed to the electron carriers
In brief, what happens in the link reaction?
Pyruvate enters the mitochondrion, is decarboxylated, dehydrogenated, and combines with coenzyme A to to give acetyl coenzyme A. The removed hydrogen is then passed to the electron carriers
In brief, what happens in The Krebs cycle?
A cyclical series of reactions during which hydrogen is passed to electron carriers, carbon dioxide is removed and the starting reagents are regenerated
In brief, what happens in The electron transfer chain?
The hydrogen from glycolysis and Krebs cycle is split to release electrons. These pass through carriers and generate ATP. The hydrogen reforms and is combined with oxygen to release water
Where does glycolysis occur?
Cell cytoplasm
Does glycolysis occur aerobically or anaerobically?
Both
What happens to glucose first in glycolysis?
It is phosphorylated
(Glycolysis) How is glucose phosphorylated?
ATP is used to add a phosphate group to glucose
(Glycolysis) What does phosphorylating glucose do to the glucose?
It makes it more reactive, allowing it to be broken down
(Glycolysis) What is the name of phosphorylated glucose?
Hexose bisphosphate
(Glycolysis) What is the hexose bisphosphate molecule converted into?
Two molecules of a 3C sugar phosphate called Triose Phosphate
(Glycolysis) What happens to the two triose phosphate molecules?
They are oxidised
(Glycolysis) What happens to the hydrogen removed from the TP molecules?
It is passed to NAD which reduces it
(Glycolysis) What is NAD?
A coenzyme
(Glycolysis) What enzymes remove hydrogen from the TP molecules?
Dehydrogenases
In glycolysis what happens to the hydrogen atoms picked by NAD?
They are used to generate four molecules of ATP
(Glycolysis) When hydrogen is removed from TP what is produced?
Pyruvic acid
In what conditions does the link reaction occur?
Aerobic
What happens to pyruvic acid during the link reaction?
It enters the mitochondrian
(Link reaction) What happens to pyruvic acid once it enters the link reaction?
Carboxylase enzymes remove carbon dioxide and dehydrogenases remove hydrogen from pyruvic acid
(Link reaction) What happens to the pyruvic acid once carbon dioxide and hydrogen are removed from it?
The pyruvic acid is combined with co enzyme A
(Link reaction) What do coenzyme A and pyruvic acid combine to form?
ACETYLCOENZYME A
What conditions do the Krebs cycle occur under?
Aerobic
What happens to acetyl coenzyme A in the Krebs cycle?
Acetyl coenzyme A is combines with oxaloacetate to form citrate
(Krebs cycle) What happens to the citrate molecule?
It enters the Krebs cycle and a series of decarboxylation and dehydrogenation reactions occur
(Krebs cycle) What happens to the carbon dioxide removed from the citrate molecule?
It is released
(Krebs cycle) What happens to the hydrogen removed from the citrate molecule?
It is passed to coenzymes such as NAD and FAD to reduce them
How many ATP molecules are generated in the Krebs cycle?
2
(Krebs cycle) What happens to the reduced NAD and reduced FAD?
They go onto the electron transfer chain
(Krebs cycle) What happens after the regeneration of NAD and FAD?
The oxaloacetate is regenerated
(Krebs cycle) What happens to the regenerated oxaloacetate?
It recombined with acetylcoenzyme A to begin the cycle again
What conditions does the electron transfer chain require?
Aerobic conditions
(ETC) What happens to the reduced co enzymes NAD and FAD?
They are reoxidised by dehydrogenases located on the cristi on the inner membrane of the mitochondrian
(ETC) What happens to the hydrogen atoms that have been removed from the reduced coenzymes NAD and FAD?
They are split into a hydrogen ion and an electron
(ETC) What happens to the electrons split from the hydrogen atoms?
They pass through a series of electron carriers which are at successively lower energy levels
(ETC) What happens to electrons as they pass through the series of electron carriers?
Some of there energy is released
What is the energy lost through the ETC used for?
To convert ADP to ATP (phosphorylate ADP)
What are the overall reactions of the ETC known as?
Oxidative phosphorylation
In the ETC what is oxidised?
The coenzymes NAD and FAD
In the ETC what is phosphorylated?
ADP to ATP using the energy lost from the passing of electrons (from the splitting of the hydrogen atoms (from the oxidizing of the NAD and FAD)) along the electron transfer chain
What happens to the hydrogen ions at the end of the ETC?
They recombine with the electrons from the end of the ETC to form hydrogen which immediately combines with oxygen to form water
What does aerobic respiration produce in animals?
Lactate
What does anaerobic respiration produce in plants and fungi?
Ethanol and carbon dioxide
