Topic 5 - Respiration Flashcards
What is the structure of the mitochondria?
Outer membrane: controls entry and exit of materials
Inner membrane: folded into cristae, providing a large surface area for enzymes involved in respiration
Matrix: contains enzymes ribosomes and mitochondrial DNA for the production of proteins needed for respiration
What reasons might cells need ATP?
Active transport: movement of molecules against a concentration gradient
Metabolic processes: synthesis of macromolecules and DNA replication
Movement: muscle contraction etc
Secretion: energy needed for vesicles formation and exocytosis
Cell division
What adaptions do the mitochondria have?
Abundance: cells requiring greater amounts of ATP contain a greater number of mitochondria
Cristae: provide large surface area for electron carriers and ATP synthase in the inner membrane
Matrix: contains enzymes for the Krebs cycle and other stages of respiration
What is aerobic respiration?
The process of breaking down a respiratory substrate to realise carbon dioxide and produce energy in the form of ATP
Hydrogen is combined with oxygen to form water, releasing energy in the process
What are the four key stages of aerobic respiration?
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
Where does glycolysis occurs?
Cytoplasm
Where does the link reaction occur?
Mitochondrial matrix
Where is the Krebs cycle?
Mitochondrial matrix
Where does oxidative phosphorylation?
Inner mitochondrial membrane
Summarise glycolysis
- Phosphorylation and splitting of glucose
- glucose (6C) is phosphorylated by 2 ATP into glucose phosphate
- glucose phosphate splits into 2 molecules of triose phosphate
- triose phosphate is oxidised into pyruvate
- NAD is reduced and ATP resythnesises
Summarise the link reaction
- pyruvate is oxidised into acetate CO2 and NADH and co enzyme A is formed
- co enzyme A combines with the acetyl to form acetyl co enzyme A
What are the products of glycolysis?
2 pyruvate
2 net molecules of ATP
2 NADH
Summarise the Krebs cycle
- acetyl coenzyme A combines with a 4 carbon compound to form a 6 carbon compound
- co enzyme A is recycled
- CO2 is removed, hydrogen is removed to give a four carbon molecule and a single ATP
What is produced from a single acetyl coenzyme A?
Reduced coenzymes (NADH and FADH)
1 ATP
2 CO2
What is a coenzyme?
Molecules that enzymes require to function
What is oxidative phosphorylation?
Use of electrons associated with NADH and FADH released from the Krebs cycle to synthesis ATP
Summarise oxidative phosphorylation
- NADH and FADH (from glycolysis and Krebs) donate electron to the first molecules in the electron transport chain
- electrons pass along a chain of electron transfer molecules in a series of oxidation reduction reactions
- during this energy. Is released causing active transport of protons across the inner mitochondrial membrane and the inter membrane space.
-protons accumulate before diffusing back into the matrix through ATP synthase channels - at the end of the chain electrons combine with protons and oxygen to from water
- oxygen is the final electron acceptor so that hydrogen ions and electrons don’t back up and pause respiration
How is ATP made in phosphorylation?
For every proton that passes through the channel, a molecule of ATP is synthesised.
What is chemiosmosis?
Protons diffuse down their electronschemcial gradient through ATP synthase.
What is anaerobic respiration?
In the absence of oxygen.
Why is it that the Krebs cycle and the electron transfer chain cannot continue in aerobic respiration?
FAD and NAD are reduced. So there is no FAD or NAD available to take up the H+ produced during the Krebs cycle and deliver it to the electron transfer chain.
What factors allow glycolysis to continue during anaerobic respiration?
Pyruvate and hydrogen must be constantly removed.
Hydrogen must be released from the reduced NAD to regenerate it.
If not glycolysis stops as there is no available NAD to take up hydrogen.
How is replenishment of NAD achieved in aerobic respiration?
Pyruvate molecule accepting the hydrogen from NADH
In animals during aerobic respiration what does pyruvate + NADH = ?
Lactate + NAD
What does lactate do?
Acidic and causes cramp and muscle fatigue. Causes pH to change which can affect enzyme activity.
How is lactate removed?
When oxygen is available it is oxidised back into lactic acid.
If oxygen is not available it is removed by the blood and taken to the liver and converted to glycogen
In plants during aerobic respiration what does pyruvate + NADH =?
Ethanol + carbon dioxide +NAD
