Respiration Flashcards
what is the need for cellular respiration
- transporting substances across membranes eg, active transport
-maintaining body temperature
-anabolic reactions
-movement eg. contraction of muscles
what is the structure of the mitochondrion (look at pic)
Glycolysis-
where does it occur?
does it need oxygen?
outline the process of glycolysis?
-in the cytosol of the cytoplasm of the cell
-no, it is an anaerobic process
-phosphorylation of glucose by adding 2 phosphates from 2 from ATP
-forming 1 hexose 1,6 bisphosphate and 2 ADP
-then, splitting into 2 triose phosphate (TP)
-each molecule of TP is oxidised by NAD+ to form 2 pyruvate
-pyruvate produced from TP
-total production of 4 ATP, and a net production of 2 ATP and reduced NAD
glycolysis-
what then happens to the 2 pyruvate molecules?
-the 2 pyruvate molecules are actively transported into the matrix of the mitochondria for the link reaction
link reaction-
where does the link reaction take place?
describe what happens?
-in the mitochondrial matrix
-pyruvate is decarboxylated = 1 carbon atom is removed from pyruvate in the form of CO2
-NAD is reduced to NADH = it collects hydrogen from pyruvate, changing pyruvate into acetate
-Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A (acetyl CoA)
-no ATP is produced
link reaction-
how many times does the link reaction happen for every glucose molecule?
so for each glucose molecule:
-2 pyruvate molecules are made for every glucose molecule that enters glycolysis. So the link reaction and the krebs cycle happen twice for every glucose molecule
•2 molecules of acetyl CoA go into the krebs cycle
•2 CO2 molecules are released as a waste product of respiration
•2 molecules of reduced NAD are formed and go to oxidative phosphorylation
krebs cycle-
where does it take place?
what does it involve?
how many times does it happen per glucose molecule?
-in the mitochondrial matrix
-a series of oxidation-reduction reactions
-happens once for every pyruvate molecule so happens twice for every glucose molecule
krebs cycle-
describe:
1?
2?
3?
- *the acetyl group from acetyl CoA combines with oxaloacetate to form citrate (citric acid), this is catalysed by citrate synthase
*Coenzyme A goes back to the link reaction to be used again - *the 6C citrate molecule is converted to a 5C molecule
* decarboxylation occurs, where CO2 is removed
* dehydrogenation also occurs where hydrogen is removed
* the hydrogen is used to produce reduced NAD (NADH) from NAD - *the 5C molecule is then converted to a 4C molecule
*decarboxylation and dehydrogenation occur
-ADP + Pi is used to change the 4C compound into another 4C compound, producing 1 reduced FAD
-making a third 4C compound which is oxidised to form oxaloacetate and 2 reduced NAD -> ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP = when a phosphate group is directly transferred from one molecule to another it’s called substrate-level phosphorylation.
*citrate has now been converted to oxaloacetate
oxidative phosphorylation-
where does it take place?
what is this process?
how many ATP is made per one glucose?
-in the inner mitochondrial matrix
-where the energy carried by electrons, from reduced NAD and reduced FAD is used to make ATP
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oxidative phosphorylation-
explain the 7 steps:
1? hydrogen atoms are released from?
2? what do electrons move along? where is the electron transport chain located?
3? what is the energy used by?
4? what is the concentration?
5? what do the protons move down?
6? what process is this?
7? and what is the final electron acceptor?
- hydrogen atoms are released from reduced NAD and reduced FAD as they are oxidised to NAD and FAD. The H stops split into protons and electrons
- the electrons move along the electron transport chain, losing energy at each of the 3 electron carriers
-in the inner mitochondrial membrane which is folded into cristae - this energy is used by the electron carriers to pump protons from the mitochondrial matrix into the intermembrane space
- the concentration of protons is now higher in the intermembrane space than in the mitochondrial matrix = this forms an electrochemical gradient
- protons move down the electrochemical gradient, back into the mitochondrial matrix, via ATP synthase = this movement drives the synthesis of ATP from ADP and Pi
- this process of ATP production driven by the movement of H+ ions across a membrane due to electrons moving down an electron transport chain is called CHEMISOMOSIS (THE CHEMIOSMOTIC THEORY).
- in the mitochondrial matrix, at the end of the transport chain, the protons, electrons and O2 from the blood combine to form water
-oxygen is the final electron acceptor
Anaerobic respiration-
what are the two types of anaerobic respiration?
how are they similar?
how do they differ?
•alcoholic fermentation
•lactate fermentation
-both take place in the cytoplasm and both start with glycolysis
-which organism they occur in and what happens to the pyruvate
lactate fermentation-
where does lactate fermentation occur?
what does it produce?
-in mammals
-lactate
lactate fermentation-
what happens?
1?
2?
3?
4?
5?
- reduced NAD from glycolysis transfers hydrogen to pyruvate to form lactate and NAD
-pyruvate is reduced to lactate by lactate dehydrogenase
-pyruvate is the hydrogen acceptor
- NAD can then be reused in glycolysis
- the production of lactate regenerates NAD so glycolysis can continue even in the absence of oxygen as ATP can still be produced
- our cells can tolerate a high level of lactate for short periods of time when they can’t get enough ATp
- however, too much lactate is toxic and is removed from the cells into the bloodstream. the liver takes up lactate from the bloodstream and converts it back into glucose in a process called glycogenesis
alcoholic fermentation-
where does it occur?
what does it produce?
-yeast cells
-ethanol
alcoholic fermentation-
what happens?
-sugar converted to ethanol in aerobic respiration.
-sugar undergoes glycolysis
-pyruvate is decarboxylated as it loses carbon dioxide to form ethonal
- reduced NAD from glycolysis transfers hydrogen to ethonal (so ethanal is reduced) to form ethanol (by ethanol dehydrogenase) and NAD
-ethanal is the hydrogen acceptor
- this production of ethanol also regenerates NAD so glycolysis can continue in the absence of oxygen
Why is the ATP yield from anaerobic respiration always lower than from aerobic respiration?
and?
-because anaerobic respiration only includes one energy-releasing stage (glycolysis) which only produces 2 ATP per glucose
-the energy-releasing reactions of the krebs cycle and oxidative phosphorylation need oxygen.
cells can respire other carbohydrates, lipids and proteins, not just glucose. So, any biological molecule that can be broken down in respiration to release energy is called?
draw the energy value table?
what has the highest energy value? why?
-a respiratory substrate
respiratory substrate: average energy value:
•carbohydrates 15.8
•proteins 17.0
•lipids 39.4
-lipids because most ATP is made in oxidative phosphorylation which requires hydrogen atoms from reduced NAD and reduced FAD. So, the respiratory substrates that contain more hydrogen atoms per unit of mass cause more ATP to be produced.
what is the respiratory quotient?
equation?
what does it mean if the RQ value is a low number? what is the usual RQ for humans?
why is RQ useful?
what are high RQs?
why do plants sometimes have a low RQ?
-the volume of carbon dioxide produced when that substrate is respired, divided by the volume of oxygen consumed, in a set period of time
RQ = volume of CO2 released/volume of O2 consumed
-that more oxygen is needed to oxidise that substrate, normal for humans is between 0.7 and 1.0
-it tells you what kind of respiratory substrate an organism is respiring and what type of respiration its using
-greater than 1, this means that the organism is short of oxygen and his have to respire anaerobically as well as aerobically
-because the CO2 released in respiration is used for photosynthesis (so it’s not measured)
look at yeast practical of aerobic and anaerobic respiration
look at the respiratory chamber practical
describe the production of ATP by substrate-level phosphorylation in different stages of respiration-
-2 ATP molecules per glucose from glycolysis
-when TP is converted to pyruvate
-4 ATP made but 2 used up in glycolysis so net yield of 2 ATP in glycolysis
-1 ATP produced per turn of the Krebs cycle/acetyl CoA
-when the 5C compound is converted to 4C compound/ocaloacetate
summarise the importance of coenzymes in respiration. Include details of the molecules and processes involved-
Coenzyme A:
-transfers acetate from link reaction to Krebs cycle
ADP/ATP:
-phosphorylation of glucose to form hexose 1,6 bisphosphate in glycolysis
-dephosphorylation of TP in glycolysis
-dephosphorylation of intermediate compound in the Krebs cycle
-formation of substrate-level phosphorylation
-formation from oxidative phosphorylation, harnessing chemical energy from chemiosmosis
NAD:
-oxidation of TP in glycolysis
-oxidation of pyruvate in link reaction
-oxidation of intermediate compounds in the Krebs cycle
-addition of electrons (reduction) to electron transport chain in oxidative phosphorylation
-reduction of pyruvate in lactate fermentation
-reduction of ethanal in alcoholic fermentation
FAD:
-oxidation of intermediate compounds in Krebs cycle
outline the process involved in the generation of ATP through chemiosmosis-
-occurs in mitochondria
-involves inner membrane and the matrix
-involves movement of hydrogen across membrane
-using the enzyme ATP synthase
-hydrogen ions pumped out of matrix into intermembrane space
-creating a H+ gradient
-ATP synthase produces ATP from ADP + Pi
-H+ ions move from an area of high concentration to low concentration
-some H+ ions leak back into matrix so process isn’t completely efficient
outline how ATP is produced in mitochondria by chemiosmosis-
-a H+ ion gradient is established as H+ is pumped into intermembrane space
-H+ ions flow down a concentration gradient
-from intermembrane space to the matrix
-through the enzyme ATP synthase
