M5, C18 Respiration Flashcards
define respiration
the process by which organisms use the energy stored in complex molecules to generate ATP
give some examples of what ATP is used for
active transport movement of muscles DNA replication exo/endocytosis synthesis of large molecules
how much energy is released when you hydrolyse ATP to ADP
30.6 kJmol^-1
what is the structure of ATP
3 phosphates
ribose sugar
adenine base
what is the word equation and symbol equation for aerobic respiration
glucose + oxygen -> carbon dioxide + water + 36ATP
look up symbol equation
what is the word and symbol equation for anaerobic respiration in plants
glucose -> ethanol + carbon dioxide + 2ATP
look up symbol
what is the word and symbol equation for anaerobic respiration in animals
glucose -> lactate + 2ATP
what is the main difference between aerobic respiration and anaerobic respiration in terms of how much ATP is produced
aerobic respiration produces 36ATP but anaerobic produces 2ATP so aerobic produces significantly more
what are all the features of the mitochondria
- inner and outer membrane
- DNA
- ribosomes
- ATP synthase
- matrix (fluid inside)
- cristae (folds of the inner membrane)
- granules
what are the similarities between the structures of chloroplasts and mitochondria
- both have a double membrane
- both have the enzyme ATP synthase
- both have a folded inner membrane
- both have their own DNA and ribosomes
- similar shape (biconvex)
- both have a fluid-filled centre
describe the shape, size and distribution of mitochondria
- rod shaped or thread like
- up to 1µm diameter
- 2-5µm long
- active cells have more mitochondria
- an athlete may have larger mitochondria and this is due to them having longer and more densely packed cristae
- moved by cytoskeleton
- in some cells they’re positioned near a site of high ATP demand
what are the 4 stages of aerobic respiration and where do they all occur
1) glycolysis (cytoplasm)
2) link reaction (matrix)
3) Krebs cycle (matrix)
4) electron transport chain / oxidative phosphorylation (membrane of the cristae)
what are the products of glycolysis
2 reduced NAD
2 pyruvate
2 ATP
what is the process of glycolysis
1) Phosphorylation - glucose (6C) is phosphorylated by adding a phosphate from a molecule of ATP.
2) This creates one molecule of hexose phosphate (6C) and a molecule of ADP.
3) Hexose phosphate is phosphorylated by ATP to form hexose bisphosphate (6C) and another molecule of ADP.
4) Hexose bisphosphate is split up into 2 molecules of triose phosphate (3C).
5) Triose phosphate is oxidised (loses hydrogen), forming 2 molecules of pyruvate (3C).
6) NAD collects the hydrogen ions, forming 2 reduced NAD.
7) 4 ATP are produced but 2 were used up in stage 1 so there’s a net gain of 2 ATP.
what is the process of the link reaction
If there’s enough oxygen, pyruvate is actively transported into the matrix of the mitochondria.
1) Pyruvate is decarboxylated so one carbon atom is removed from pyruvate in the form of carbon dioxide.
2) NAD is reduced - it collects hydrogen from pyruvate, changing pyruvate into acetate.
3) Acetate is combined with coenzyme A to form acetyl coenzyme A.
what are the products of the link reaction per glucose molecule
2 acetyl coenzyme A
2 carbon dioxide
2 NADH
(there are 2 of everything because for every glucose molecule, the link reaction happens twice)
what are the steps of the Krebs Cycle?
1) Acetyl coenzyme A from the link reaction combines with oxaloacetate to form citrate (citric acid).
2) Citrate is decarboxylated and dehydrogenated to form a 5-carbon compound. NAD accepts the hydrogen atoms and becomes reduced.
3) This 5-carbon compound then is decarboxylated and dehydrogenated too. This forms a 4-carbon compound and another NADH.
4) The 4-carbon compound is changed to another 4-carbon compound. During this a molecule of ADP is phosphorylated to produce an ATP molecule.
5) This is changed into another 4-carbon compound. A pair of hydrogen atoms is removed and accepted by the coenzyme FAD, which is reduced.
6) The third 4-carbon compound is dehydrogenated and regenerates oxaloacetate. Another molecule of NAD is reduced.
What are the products of the krebs cycle per glucose molecule
6 NADH
2 FADH
4 carbon dioxide
2 ATP
(per glucose molecule, the Krebs cycle happens twice. so for one cycle, half the numbers)
What is the process of oxidative phosphorylation
1) The NADH or FADH from the Krebs cycle are reoxidised and they release a hydrogen atom.
2) The hydrogen atom splits into an electron and hydrogen ion (proton).
3) The electron passes down the electron carrier chain, releasing energy.
4) This energy is used to pump the hydrogen ions from the matrix into the intermembrane space.
5) There is now a higher concentration of hydrogen ions in the intermembrane space so they diffuse down a concentration gradient through a channel protein, activating ATP synthase.
6) ATP synthase catalyses the reaction to produce ATP.
7) The hydrogen ions are collected, along with the electrons from the carrier chain and they react with oxygen to produce water.
For aerobic respiration, if 2.5 ATP are made for every reduced NAD and 1.5 ATP are made for every reduced FAD, how many ATP will be made altogether for one glucose molecule?
Glycolysis - 2 ATP and 2 NADH
2+(2X2.5) = 7
Link reaction - 2 NADH
2X2.5 = 5
Krebs cycle - 2 ATP, 6 NADH, 2 FADH
2+(6X2.5)+(2X1.5) = 20
7+5+20 = 32 ATP
It is thought that between 32-36 ATP are made from one glucose molecule in aerobic respiration. Why is this, however, not all used for energy?
1) Some ATP is used to actively transport pyruvate into the mitochondria.
2) Some ATP is used to transport ADP into the cell to combine with phosphate ion.
3) Some hydrogen ions (protons) leak across the mitochondrial membrane, reducing the number available for use in chemiosmosis.
what happens to aerobic respiration if there’s no oxygen
In oxidative phosphorylation, oxygen is the final electron acceptor (when water is formed at the end). So without oxygen, the electron transport chain stops as does the Krebs cycle and link reaction.
Only glycolysis occurs - therefore significantly less ATP is made.
Leads to anaerobic respiration.
What type of anaerobic respiration occurs in mammals and describe what happens
Lactate fermentation:
The pyruvate formed in glycolysis accepts the hydrogen toms from NADH, turning pyruvate into lactate.
Lactate dehydrogenase catalyses this.
The oxidised NAD is now available to be reused in more glycolysis and generate more ATP.
what is the main aim of lactate fermentation and alcoholic fermentation
To make NAD which can be used in glycolysis to make ATP.
