Respiration Flashcards
What is the equation for respiration?
Glucose + Oxygen –> Carbon dioxide + Water + ATP
C6H12O6 + 6O2 –> 6CO2 + H2O + ATP
Why is glucose not suitable as an immediate energy source
The release of energy would be too large, would produce too much heat and would be uncontrolable
How is the mitochondria adapted to its function
-Highly folded membrane forming cristae–> large surface area- greater number of chemical reactions
-70s ribosomes for protein synthesis- reactions can occur faster
-ATP synthase to produce large amounts of ATP.
-thin membrane- short diffusion distance
-circular DNA- own genome so transcription and translation can happen faster.
Where does each stage of respiration occur
- Glycolysis- cytoplasm/ cytosol of the cell
- Link reaction- matrix of the mitochondria/ mitochondrial matrix
- Krebs cycle- mitochondrial matrix
- ETC- mitochondrial membranes
State the two ways that ATP can be generated
- Substrate-level phosphorylation- ATP generated directly through energy released via respiration reactions. this occurs in Glycolysis and the krebs cycle
- Oxidative Phosphorylation- ATP generated from chemical energy released when a reduced hydrogen carrier or coenzyme has been oxidised in the ETC.
Explain the process of glycolysis.
Involves the conversion of glucose to pyruvate
1. Activation of glucose my phosphorylation, requires the hydrolysis of 2 X ATP to 2X ADP
2. Glucose phosphate then splits into 2 X Triose Phosphate
3. Triose Phosphate is oxidised to pyruvate involving the loss of H with the use of dehydrogenase enzyme which reduces NAD to NADH2. ATP produced via substrate level phosphorylation
What are the net yields for glycolysis
2 ATP
2 Reduced NAD
2 Pyruvate
Explain the process of the link reaction
Pyruvate is actively transported into the mitochondrial matrix (Low concentration in cytoplasm and high concentration in the matrix
1. Pyruvate (3C) is oxidised to acetate and the Hydrogen is removed to reduce NAD and a molecule of coenzyme A binds producing the final product of acetylcoenzyme A. Co2 is also lost in this reaction through decarboxylation. No ATP is produced
The link reaction net yield
2 NADH
2 CO2
2 AcetylCoenzyme A
Pyruvate (3c) + NAD + coA –> Acetylco A (2C) + NADH2 + CO2
Describe the process of the krebs cycle
A series of redox reactions that takes place in the matrix of the mitochondria.
1. 2C acetyl Co A combines with 4C molecule to produce a 6C molecule. NAD+ is converted to NADH2 through the addition of a H+ ion from pyruvate. CO2 is released through decarboxylation.
2. This forms a 5Carbon compund
3. Substrate level phosphorylation where ADP + Pi forms ATP. FAD forms FADH2, 2X NAD+ forms 2X NADH2 forming a 4 carbon compound. CO2 released again between 5c and 4c.
Net yields of the krebs cycle
1 Acetyl CoA produces 2CO2, 3NADH, 1FADH, 1 ATP but because the cycle happens twice the net yield is:
4 CO2
6 NADH
2 FADH
2 ATP
What is the overall net yield for the three processes
per glucose molecule:
10 NADH
4ATP
2FADH
Describe the ETC
The reduced Hydrogen carriers produced in glycolysis, link and krebs cycle will produceATP in the oxidative phosphorylation
1. Reduced NAD and FAD are oxidised losing H+
2. the electrons from the hydrogen atom pass down the ETC in the mitochondrial membranes in a series of redox reactions
3. As they pass down they lose energy which some is used to pump H+ through the inner mitochondrial membrane and into the intermembrane space
4. Some energy lost as heat
5. H+ diffuse down a proton gradient into the matrix via ATP synthase
6. Electrons and H+ combine with O2 gas to form water
7. O2 is the final terminal electron acceptor.
Water is a waste product of aerobic respiration. describe how water is formed
- Oxygen is terminal electron acceptor
- Combines with electrons and protons to form water
Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP
- Reduced NAD and FAD
- electrons transferred from coenzyme to coenzyme through a series of redox reactions
- energy released as electrons pass down ETC
- Energy used to synthesise ATP from ADP + Pi
- Protons diffuse back through ATP synthase
describe how ATP is formed in the mitochondria
- Substrate-level phosphorylation/ ATP produced in the Kreb’s cycle
- krebs cycle produces reduced NAD and FAD
- Electrons released from these
- Electrons pass through ETC through a series of redox reactions
- energy released
- protons pumped into intermembrane space
ADP + pi –> ATP
describe the events of oxidative phosphorylation
- NAD reduced
- ETC on inner membrane
- H+ ions transferred from coenzyme to coenzyme through redox reactions
- Energy released as electrons passed on
- H+ pumped into intermembrane space
- protons flow back through stalked particles
- energy used to form atp
describe how oxidation takes place in the krebs cycle
- removal of hydrogen
- by enzymes/dehydrogenase
- Reduced NAD formed
- In kreb cycle FAD used as well
Alternative respiratory substrates: Lipids
Lipids hydrolysed into glycerol and fatty acids:
Glycerol is phosphorylated and converted into TP which enters glycolysis and the krebs cycle, fatty acids are broken down into 2 Carbon fragments and converted into acetyl co A. Oxidation of fatty acids yeilds many hydrogen atoms to reduce NAD/FAD to be used in oxidative phopshorylation.
To summarise: Triglycerides
/ \
Fatty acid Glycerol
I I
Acetyl Co A
TriosePhopshate
I I
Krebs Glycolysis
Alternative respiratory substrates: proteins
Amino acids removed (deamination)
Enter respiratory pathway at different stages depending on number of carbons: 3C- pyruvate
4C and 5C- Krebs cycle intermediates
Summary:
Proteins
I
Amino acids
I
Deamination
/ \
3C into pyruvate 4C and 5C
Anaerobic respiration
Link reaction, krebs cycle, ETC stop as there is no oxygen to act as final terminal acceptor
Glycolysis does not require oxygen and can continue in the abscence of O2, however to continue NAD must be regenerated
The H from reduced NAD is now accepted by pyruvate rather than passing through ETC
Pyruvate is reduced to lactate in animals and ethanol and CO2 in plants
Total net release of aerobic respiration
38 ATP
Respirometers
As the animal and plant respires- o2 is used for aerobic respiration, this reduces the volume in the chamber and reduces the pressure. KOH absorbs the CO2 released- the link moves from higher to lower pressure
Animal, aerobic, producing CO2
pressure with CO2 absorber: CO2 absorbed, decrease in pressure, liquid moves towards organism
pressure without CO2 absorber: Equillibrium, no movement
Yeast, Anaerobic, producing ethanol and CO2
Pressure with CO2 absorber: No O2 in and CO2 absorbed. equillibium. No movement
Without absorber: No oxygen used, no CO2 absorbed so builds up, pressure increases, liquid moves away from organism
Plant, aerobic, producing CO2
With CO2 absorber: CO2 absorbed, decrease in pressure, liquid moves towards organism
Without absorber: Equillibrium, no movement
Bacteria, aerobic producing CO2
With absorber: CO2 absorbed, decrease in pressure, liquid moves towards organism
Without: equillibrium, no movement
Bacteria, anaerobic, producing ethanol with CO2
With: CO2 absorbed, equillibrium, no movement
Without: No oxygen used, no CO2 absorbed, pressure increase, liquid moves away from organism
Maggot, anaerobic producing Lactate
With: No CO2 absorbed, no O2 uptake, equillibrium, no movement
Without: equillibrium, no movement
Reasons why respirometer should be left for 10 when placed in water bath
- Equillibrium reaches
- Allow for expansion
- allow respiration rate of seeds to stabilise
Plants produce ATP in their chloroplasts during photosynthesis. They also produce it during photosynthesis. Why is it important that produce it in both processes
- In the dark no ATP produced in photosynthesis
- Some tissue unable to photosynthesise
- ATP can’t move from cell to cell
- uses more ATP than produced in photosynthesis
- ATP needed for active transport
Describe how acetyl co enzyme A is formed in the link reaction
Hydrogen removed from pyruvate and CO2 released
Explain why converting pyruvate to lactate allows the continued production of ATP during anaerobic respiration.
regenerates NAD- NAD used in glycolysis
In muscles, some of the lactate is converted back to pyruvate when they are well supplied with oxygen. suggest an advantage
Lactic acid can cause cramp and fatigue
Explain why O2 is needed for the production of ATP on the cristae of the mitochondrion
ATP formed as electrons passes down the ETC
Electrons can’t be passed along with no O2 to accept them
Explain why the scientist did not use glucose
Glucose used in glycolysis- glucose can’t cross mitochondrial membrane
AR produces more ATP per molecule of glucose than anerobic. Explain why
O2 is the terminal acceptor, oxidative phosphorylation.
Only glycolysis used to produce ATP for anaerobic
Suggest an explanation for the effect of temperature on the rate of CO2 release
faster rate of respiration, more CO2 produced, enzymes faster, spiracles open more often.
