Respiration Flashcards
What is aerobic respiration?
The oxidation of glucose into carbon dioxide and water with release of energy
What is the equation of respiration?
Glucose + oxygen -> carbon dioxide + water (+energy)
What happens to energy in respiration
It is released or transferred, not produced
What does respiration occur in a series of?
Enzyme controlled steps - this means the release of energy is controlled
What nucleotide is ATP
Adenosine Triphosphate
What does ATP consist of
3 phosphate groups combined with adenine and pentose sugar, ribose
What type of energy store is ATP
The immediate, but short term energy store of cells
What is ATP synthesised from?
ADP (adenosine diphosphate) and inorganic phosphate (Pi) during phosphorylation
What happens when ATP is hydrolysed
ATP has a high free energy of hydrolysis meaning when it is hydrolysed a relatively large amount of energy is released
What happens when ATP is converted to ADP
Conversion yields energy. Conversions carried out my enzyme ATPases
Why is ATP a suitable energy store?
- hydrolysis of ATP molecules releases a small amount of energy so energy can be released in small manageable steps
- ATP hydrolysis is a single reaction releasing immediate energy and providing cell with control over energy
- ATP is small and soluble so can be transported around cell easily. Enables it to be transported from mitochondria to any part of cell
What are the uses of ATP
- energy for metabolic processes including synthesis of larger molecules
- movement
- active transport
- activates molecules via phosphorylation
Describe the structure of the mitochondria
- surrounded by a double membrane separated by intermembrane space
- outer membrane is permeable to most small molecules involved in cellular respiration
- inner membrane is highly folded forming cristae inc SA enabling more ATP to be produced.
- matrix contains many chemical compounds and some respiration reactions occur here
How is ATP produced in respiration
- substrate Level phosphorylation: direct transfer of a phosphorylated substance to ADP
- Oxidative phosphorylation: ATP is produced from ADP and Pi as electrons are transferred along a series of carriers
What are the stages of aerobic respiration
1 glycolysis
2 pyruvate oxidation (link reaction)
3 Krebs cycle
4 electron transport chain
What is glycolysis
The splitting of the hexose sugar (glucose) into two 3-carbon pyruvate molecules
What stage of respiration occurs aerobically and anaerobically
Glycolysis
Where does glycolysis occur
In fluid part of cytoplasm
What are the steps of glycolysis
1) activation of glucose by phosphorylating it. Makes glucose more reactive and uses up ATP as 2 phosphates come from hydrolysis of 2 atp molecules. Resulting molecule is fructose 1,6 bisphosphate
2) that then splits into two 3 carbon molecules of trios-phosphate, which is then oxidised through loss of hydrogen to form pyruvate with the production of 2 ATP molecules. The hydrogen atoms are collected by NAD which is reduced to form NADH.
3) overall the process from glucose to 2x pyruvate molecules results in the formation of 4 ATP and 2 NADH + H+, but the 2 ATP are used up in the process of glucose activation, so the net gain of ATP is only 2
What does the removal of hydrogen in stage 2 of glycolysis involve
Dehydrogenase enzymes in a process called dehydrogenation
What does the link reaction do?
Form a molecule called acetyl coenzyme A (acetyl CoA). This is necessary to allow the entry of a 2 carbon molecule into mitochondrial matrix
What is decarboxylation
Removal of a carbonyl group
What is dehydrogenation
The removal of hydrogen atoms
What is the process of the link reaction?
1) pyruvate is decarboxylated with the removal of one CO2
2) dehydrogenations occur with the removal of hydrogen leading to formation of NADH
3) The resulting 2 carbon (acetyl) group then combines with coenzyme A forming acetyl CoA