5.7 Respiration Flashcards
What is ATP synthesised from?
ADP + inorganic phosphate (Pi)
What are three biological processes that require the use of ATP?
Active transport, endocyctosis, DNA replication
What is the structure of ATP?
-An adenine base attached to a ribose sugar, which is attached to three phosphate groups
(3 phosphate groups, 1 ribose sugar and 1 adenine base)
What is a catabolic reaction?
Occurs within a cell. Large molecules are broken into smaller molecules
What is an anabolic reaction?
Small molecules are combined into larger molecules
What is glycolysis?
The first stage of respiration, glucose is converted into pyruvate
What is NAD?
A coenzyme (nicotinamide adenine dinucleotide) Reduced NAD carries protons and electrons to the cristae
What is phosphorylation in glycolysis?
Where glucose has 2 phosphate groups attached to form hexose bisphosphate using 2 molecules of ATP
What is hexose bisphosphate split into during glycolysis?
2 molecules of triose phosphate
What is triose phosphate converted into during the oxidation stage of glycolysis?
Pyruvate
How many carbons are found in a molecule of pyruvate?
3
Which molecule accepts the hydrogen atoms from triose phosphate when it is oxidised?
NAD
What are the products of glycolysis for every molecule of glucose?
2 x pyruvate, 2 molecules of ATP, two reduced NAD
What is the net gain of ATP in glycolysis?
2 (four are made but two are used)
Why is glycolysis an anaerobic process?
It occurs in the cytoplasm without the need for oxygen
What is the cristae?
The inner highly folded mitochondrial membrane
What is the mitochondrial matrix?
Fluid filled inner part of the mitochondria
What is the average length of mitochondrion?
2-5 micrometers
Where does the link reaction occur in the mitochondria?
The mitochondrial matrix
What is the name of the two coenzymes found in the mitochondria?
NAD & FAD
Where is the electron transport chain found in the mitochondria?
The cristae of the inner membrane
What is the name of the enzyme found in the cristae of the enzyme that synthesises ATP?
ATP synthase
What is decarboxylation?
The removal of a carboxyl group from a substrate molecule
What is the molecule released/produced from respiration?
ATP (The universal energy currency of living cells)
What is the structure of ATP?
- 3 Phosphate groups
- 1 Adenosine (-1 adenine base and -1 ribose sugar)
How is energy released from ATP?
When ATP is hydrolysed by enzymes into ADP and Pi it releases energy (Same with ADP into AMP and Pi)
What is respiration in laymen’s terms?
Breaking the large currency of energy (Glucose) into many small manageable currencies of energy (ATP)
How is ATP made ?
- (ADP + Pi -> ATP) This is done via:
- Oxidative phosphorylation, using ATP synthase
- Substrate level phosphorylation in Glycolysis and in the Krebs cycle
What is Glycolysis?
- The first stage of respiration, occurs in the cytosol of the cytoplasm
- Makes: 2 ATP and 2 reduced NAD molecules
What is oxygens purpose in aerobic respiration?
Oxygen is the final electron acceptor meaning it accepts electrons and hydrogen atoms in order to make H2O
What are the steps of Aerobic respiration?
- Glycolysis
- Link reaction
- Krebs cycle
- Oxidative phosphorylation
What are the stages of Glycolysis?
1) Phosphorylation - Glucose is phosphorylated
2) Splitting - Where the phosphorylated glucose is split into some 3 carbon molecules
3) Oxidation - (SLP) Makes: 2 ATP and 2 reduced NAD molecules
What is the link reaction?
- The second stage of aerobic respiration, occurs in the mitochondrial matrix
- Makes 1 Reduced NAD
- Waste products made: CO2
What is the Krebs cycle?
- The third stage of aerobic respiration, occurs in the mitochondrial matrix
- Makes (Per turn): 1 ATP (SL), 3 reduced NAD and 1 reduced FAD x2 because one molecule of glucose causes two turns of the cycle
- Waste products made: x2 CO2
What is NAD and FAD’s purpose?
They are hydrogen carriers
What happens in oxidative phosphorylation?
- 2H is pumped in and the pass down the electron transport chain (H+ ions are pumped into the intermembrane space of the mitochondria)
- This causes a H+ gradient used to spin the ATP synthase molecule in chemiosmosis
What happens in anaerobic respiration?
- First stage is glycolysis
- After that fermentation occurs, Lactate fermentation for mammals and Ethanol fermentation in fungi and plants
What is the process of glycolysis in terms of the carbons?
Phosphorylation
1) Glucose (6C) [ATP loses one phosphate to glucose] 2) Glucose phosphate (6C) [Another ATP loses one phosphate to glucose] 3) Hexose 1-6 bisphosphate (6C)
What is the process of glycolysis in terms of the carbons?
Splitting
[Hexose 1-6 bisphosphate is split]
4) 2x Triose phosphate (3C)
[1 NAD is released for each Triose phosphate]
[2 ATP is released for each Triose phosphate]
What is the process of glycolysis in terms of the carbons?
Oxidation
[2NAD is reduced to make 2NADH] &
[4ADP + 4Pi to make 4ATP]
5) 2x Pyruvate (3C)
What are the products from Glycolysis?
-4 ATP made, but 2ATP is used
(Net) 2ATP
-2NADH
What do dehydrogenase enzymes do?
They remove H atoms
What happens straight after Glycolysis in aerobic respiration?
The pyruvate is actively transported from the cytosol into the matrix of the mitochondria for the link reaction
What is the process of the Link reaction?
1) Pyruvate (3C)
[A carbon is lost so CO2 is produced] {decarboxylated}
& [2H molecules are lost so NADH is produced] {dehydrogenated} by pyruvate dehydrogenase
[A Co enzyme A joins with the 2 remaining carbons from pyruvate to make Acetyl CoA]
2) Acetyl CoA (2C)
What happens straight after the link reaction in aerobic respiration?
The Acetyl CoA is split into CoA and acetyl group (2C)
The Acetyl group then enters the Krebs cycle
What is the process of the Krebs cycle?
1) Acetyl group (2C) joins on to a molecule to form citrate
2) Citrate (6C)
[A carbon is lost making CO2] & [2H is lost making NADH]
3) (5C) Compound
[A carbon is lost making CO2] & [2H is lost making NADH]
4) (4C) Compound
[SLP, a phosphate is lost and ADP joins it to make ATP]
5) (4C) Compound
[FAD accepts the hydrogens, that are lost, to make FADH]
6) (4C) Compound
[NAD accepts the 2 hydrogens to make NADH]
7) Oxaloacetate (4C)
What is the process of the Krebs cycle? (shorthand)
2,6,5,4444) (CaN CaN A FaN
(2C) (6C) CaN (5C) CaN (4C) A (4C) F (4C) N (4C)
What is oxidative phosphorylation?
The formation of ATP by oxidising NADH and FADH in the presence of oxygen and the proteins of the electron transport chain
What is chemiosmosis?
The flow of protons down the concentration gradient through ATP synthase molecules
What is the process of oxidative phosphorylation? (NADH)
1) NADH releases 2H
2) The hydrogen atoms are split into the electrons and protons
3) The electrons are sent down the ETC and lose energy as they go down the electrical potential gradient
4) The energy given off by the electrons is used to pump the protons into the intermembrane space
What is the purpose of the proteins in the electron transport chain?
The proteins allow the electrons to go down the chain which is arranged in an electrical potential gradient so the protons go down to lower electrical potentials. As they travel down the chain they lose energy that is used to pump the protons into the intermembrane space
What is the movement of protons and electrons from the 2H atoms at the start of Oxidative phosphorylation?
As the electrons travel down the proteins on the electron transport chain they give off energy that is then used to pump the proteins into the intermembrane space
What is the process of oxidative phosphorylation? (FADH)
1) FADH releases 2H
2) The hydrogen atoms are split into the electrons and protons
3) The electrons are sent down the ETC onto the second protein instead of the first
What happens when the electrons reach the end of the ETC?
The electrons must be accepted by the final electron acceptor which is oxygen
(4E- & 4H+ & O2 -> 2H2O)
How is the ATP made from the H+ protons?
The H+ ions (protons) move from the intermembrane space through ATP synthase and turn into ATP
How does ATP synthase work to produce ATP from the H+ ions?
- ADP + Pi sticks to the head region and won’t move until the head moves from the axle rotating
- The H+ ions go through the channel, as they flow in they cause the axle to rotate around, this makes the head region rotate
- The ADP + Pi are then moved with the head region
- This causes the ADP + Pi to bind to create an ATP molecule
- The ATP molecule is then released from the head of the ATP synthase enzyme
What is uncoupling and how can heat energy be produced from the H+ ions in oxidative phosphorylation?
- When the H+ ions travel across the intermembrane space, flowing into the matrix but not through ATP synthase
- This means that, as the H+ ion travels across the membrane the energy produced is not converted into ATP but makes heat energy instead
- This is often done when the protons pass a thermogenic protein when crossing the membrane
What is the cristae?
The folds of the membrane, this increases the surface area for the ETC and the stalked particles
What is endosymbiotic theory?
- The theory that mitochondria has evolved from a bacterial cell that was engulfed from a eukaryotic cell making it a phagocytotic vesicle (Digestion never occurred)
- This is shown as the mitochondria have an inner and outer membrane with an intermembrane space
What is the matrix?
- Fluid in side of the inner membrane
- Packed with enzymes that are responsible for the Link reaction and the Krebs cycle
- Produces large amounts of NADH and FADH that is oxidised by the proteins in oxidative phosphorylation
How is the genetic material stored in mitochondria?
In a DNA loop inside of the matrix that is used to code for the proteins, so the concentrations of the proteins is easily regulated and balanced
What are the ribosomes inside of the mitochondria used for?
The mitochondria has its own ribosomes that are small and are used to translate mRNA from the genes in the DNA loop into the proteins inside the mitochondria
What are the stalked particles in the mitochondria used for?
The stalked particles are part of the ATP synthase enzyme that is on the cristae and is used in chemiosmosis
Why does fermentation have to occur after glycolysis in anaerobic respiration?
- Because fermentation must oxidise the NADH otherwise glycolysis would stop too
- The NADH would normally be oxidised in oxidative phosphorylation but due to there being no oxygen, fermentation must occur to allow glycolysis to continually repeat
What happens in lactate fermentation? (In mammals)
Pyruvate + NADH -> Lactate (Lactic acid) + oxidised NAD
What happens in ethanol fermentation? (In yeast and plants)
Pyruvate -> ethanal (Releasing CO2) -> {with NADH} hydrogenates ethanal to make Ethanol + oxidised NAD
How much ATP is made from Oxidative phosphorylation (The ETC and Chemiosmosis)?
28, 32 is made from the whole process of respiration
How many ATP’s does anaerobic respiration make? (Net)
2 (Only from glycolysis)
What is a facultative anaerobe?
An organism that can respire anaerobically or aerobically depending on the environment. For example: Yeast
How can you measure whether an organism is a facultative anaerobe?
1) Grow yeast in a condition with O2 and without O2
2) leave it to grow for a day
3) Measure the cell density in the culture
What is the name of the piece of apparatus used to count the number of cells and the growth of a culture yeast cell?
A Haemocytometer will show which culture of yeast cells will grow the quickest (With oxygen or without oxygen). This would be the culture with the most ATP available, so it would be expected that the cells that can respire aerobically would grow the quickest. The haemocytometer can also be used to count the number of red blood cells in a culture
What does sodium hydroxide do in the experiment that measures the oxygen uptake/respiration rate of woodlice?
The sodium hydroxide (NaOH) absorbs the CO2 in order to measure the rate of respiration. This is because, as the woodlice respire air pressure inside the tube with the woodlice would decrease as the CO2 is being absorbed by the NaOH
Why is a double test tube setup with a “U” shaped capillary tube used?
So that variables like temperature can be manipulated in order to see the effects of them on respiration rate in the woodlice. A “U” shaped capillary tube with manometer fluid inside it would be connected to the control test tube and the test tube with the woodlice in it. Both the control and the woodlice test tube would sit in a bath of water, this is so that they are both controlled and the affect of temperature on oxygen uptake/respiration rate can be measured
Why air glass beads used in the control tube?
To ensure the volume of the air is the same as the test tube with the woodlice. The glass beads must have a similar volume so that it the volume of the air is the same in both tubes
How is the rate of oxygen use measured in an experiment?
Manometer fluid would be added to the “U” shaped capillary tube. The fluid would be forced up the tube where the oxygen uptake is higher (The tube with the woodlice in it)
What is the RQ value and how is it measured?
RQ= Volume of CO2 out / Volume of CO2 in
How does the type substrate affect the RQ value? (in aerobic respiration)
Carbohydrates- 1
Proteins- 0.9
Lipids- 0.7
If anaerobic respiration takes place what is the RQ value?
> 1
How are carbohydrates respired?
- Polysaccharide structure
- It is first digested into monosaccharides then goes through isomerisation (Converting the monosaccharide into a glucose monomer to be respired)
- 15.8KJg-1
How are lipids respired?
- Fatty acids have lots of C-H bonds
- Very energy dense
- Respired by Beta oxidation of fatty acids, adds 2C into Acetyl CoA
- 39.4KJg-1
How are proteins respired?
- Digested into amino acids
- Deaminated into keto acid
- The keto acids then go into the Krebs cycle
- This can differ due to the different R groups on the amino acids in the polypeptide
- 17KJg-1
What is the final electron acceptor in respiration?
- Oxygen is the final electron acceptor
- This means that it accepts electrons and H atoms to form water
Why are phosphates added to glucose during phosphorylation in glycolysis?
- Glucose is a stable molecule
- This means that it must be activated by the addition of phosphate before it can be broken down
How can uncoupling cause a loss of weight?
- The energy from food (Stored in NADH & FADH) is not used to create ATP, as the protons do not pass through ATP synthase
- Instead the protons pass the through the intermembrane space through a thermogenic enzyme which converts this energy from food into heat energy
- This causes people to loose weight as all the energy from food is instead converted into heat energy
What are two examples of uncoupling?
- UCP1, a thermogenic enzyme which converts energy stored in NADH & FADH into heat energy
- DNTP, a poisonous chemical that causes protons to pass through the intermembrane space without flowing through ATP synthase
- This causes energy stored in NADH & FADH to be wasted and converted into heat energy
