Respiration Flashcards
4 stages of respiration
glycolysis, the link reaction, kerb cycle, oxidative phosphorylation
products of all 4 stages and how they are used in the next stage
glycolysis: glucose -> 2 pyruvate, 4ATP ( 2 net), 2 NADH
link: pyruvate -> acetyl coenzyme A, Co2, NADH
kerb cycle: acetyl coenzyme A -> 2 co2 , substrate level atp , 1 FADH, 3NADH
oxidative phosphorylation : FADH and NADH -> h+, e-,o2 = h2o, ATP
where does glycolysis occur
cytoplasm outside mitochondria
where do the link reaction and kerb cycle occur
matrix
where does oxidative phosphorylation occur
movement of h+ ions and electrons from the matrix across the inner membrane to the intermembrane space and back to the matrix again
importance of co enzymes
- required to transfer : protons, electrons and functional groups between many enzyme catalysed reactions
- NAD takes part in all stages of cellular respiration accepting 1 hydrogen at a time
- FAD is used to transfer hydrogens and electrons from the kerb cycle to the oxidative phosphorylation reaction
explain the glycolysis reaction
- glucose ( 6 carbon hexose sugar)
Phosphorylation: 2 molecules of ATP release 1 inorganic phosphate each which binds to the hexose - hexose bisphosphate (6 carbon 2 phosphates)
Lysis: binding of phosphates destabilises the molecule causing it to split - 2 triose phosphate (2x (3 carbon 1 phosphate) )
Phosphorylation: another phosphate group (found in the cytoplasm) is added to each triose phosphate - 2 triose bisphosphates (2x ( 3 carbon 2 phosphates) )
oxidation: 2 triose bisphosphate molecules are oxidised, hydrogens removed to make NADH
ATP formation: 4 molecules of ADP accept the 4 phosphates forming 4 ATP - 2 pyruvate molecules
products of glycolysis
net gain of 2 ATP
reduced NAD/ NADH
2 pyruvate molecules
explain the link reaction
2 lots of \:pyruvate ( 3 carbon) Decarboxylation - removal of 1 Co2 Reduction - removal of H \:acetyl group ( 2 carbon) + coenzyme A Combination - acetyl group and coenzyme A combine \:acetylcoenzyme A ( 2 carbon)
function of the combination stage during the link reaction
function of coenzyme A is to deliver the acetyl group to the kerb cycle once acetyl group has been released coenzyme A is reused in the link reaction
explain the kerb cycle
-acetyl coenzyme A reacts with oxaloacetate ( a 4 carbon molecule) to create a 6 carbon molecule, citrate
- coenzyme A is released to be reused in the link reaction
- series of redox reaction bring the citrate molecule back to a 4 carbon molecule
- decarboxylation and reduction of NAD takes citrate from 6c - a 5c intermediate compound
- decarboxylation, reduction of 2 NAD and 1 FAD, and synthesis of substrate level ATP
- products are: 2Co2, 3 NAD reduced to NADH, 1 FAD reduced to FADH, and substrate level ATP
Process happens twice becuase of 2 actyl coenzyme A’s
explain the oxidative phosphorylation reaction
1) reduced NAD/FAD are supplied from the kerb cycle
2) reduced NAD/FAD bind to complex 1 and are oxidised causing h+ and e- to dissociate
3) e- binds to electron carrier protein causing a series of redox reactions to occur as e- is passed along the electron transport chain
4) energy harnessed from these redox reactions is used to actively pump h+ from the matrix to the intermembrane space
5) active transport of h+ ions causes a concentration gradient
6) h+ ions move from an area of higher concentration ( intermembrane space) to an area of lower concentration ( matrix) through the ATP synthase molecule
7) movement of h+ ions causes ATP synthase molecule to rotate producing ATP
8) e- from electron transport chain combines wit h+ from ATP synthase molecule to form a hydrogen atom which binds with o2 ( present in matrix) to form h2o
Folded cristae provide a greater space for more elctron carrier protiens and ATP synthase molecules
Theoretical yield of ATP from to 1 molecule of glucose
32 ATP
Why is theoretical yield only theoretical
- Leaky membranes may allow H+ ions to diffuse back across the inner membrane, not through the ATP synthase molecule
- h+ may go elsewhere
- ATP may be used in the active transport of h+
Anaerobic respiration in mammals
Lactate fermentation
Glucose -> triose phosphate via phosphorylation and lysis ( uses 2 ATP)
triose phosphate -> pyruvate via the reduction of NAD, produces 4 ATP
Pyruvate is broken down by lactate dehydrogenase into lactate, this oxidises the reduced NAD
Cannot be sustained as lactate is converted to lactic acid which is toxic and harms cells
Has lower yelid because the : link reaction, krebs, and oxidative phosphorylation cannot continue
Anaerobic respiration in yeast
Ethanol fermentation
Glucose -> triose phosphate via phosphorylation and lysis ( uses 2 ATP)
triose phosphate -> pyruvate via the reduction of NAD, produces 4 ATP
Pyruvate is converted into ethanal ( co2 is removed) by pyruvate dehydrogenase
Ethanal is converted to ethanol by ethanol dehydrogenase, this process oxidises the reduced NAD
Respiratory substrate
Is a organic substance that can be used for respiration
Which molecules provide the most energy and why
Lipids provide twice as much energy as carbohydrates or proteins
This is because lipids contain more hydrogen carbon bonds ( more h atoms)
H atoms used to generate the most ATP is oxidative phosphorylation
Need for cellular respiration
To release energy to fuel living processes
E.g transporting stubstances across membranes, anabolic reactions, movement, maintaining body temprature
Structure of the mitochondria
Outer membrane - seperates the contents of the mitochondrion from the rest of the cell, creating cellular conditions ideal for aerboic respiration
Folded (cristae) Inner membrane - site of electron transport chain and ATP synthase molecule, both used in oxidative phosporylation
Intermembrane space - low ph due to high conc of h+ ions, creates conc graident across inner membrane during oxidative phosphorylation, essential for ATP synthesis
Matrix - contains enzymes for the krebs cycle and the link reaction, also contains mitochondrial DNA
Large SA due to presnce of cristea enables membrane to hold manu electron transport chain protiens and ATP synthase enzymes increase ATP production.
4 stages of respiration, description and location
Glycolysis- phosphorylation and splitting of glucose , cell cytoplasm
Link reaction - decarboxylation and dehydrogenation of pyruvate, matrix of mitochondria
Krebs cycle - cyclical pathway with enzyme controled reactions, matrix of mitochondria
Oxidative phosphorylation - production of ATP through oxidatipn of hydrogen atoms, inner membrane of mitochondria
Role of coenzyme A
Supplies the acetyl group from the link reaction to the krebs cycle
Respiratory quotients of different molecues
Co2 produced / oxygen consumed
Carbohydrates = 1
Proteins = 0.9
Lipids = 0.7
Why do different molecules have different energy values
Dependant on the number of hydrogen atoms become available when the molecule is broken down.
Hydrogen carrier molecues NAD and FAD pick them up, become redcued, and transfee them to the inner mitchondrial membrane
More hydrogens are then split in the electron transport chain creating a stronger proton graident meaning level of chemiosmosis is higher
Why are glass beeds usd in respirmoeters
Keep volume in both tubes the same, allows us to detect any change in volume
= volume means = pressure in both tubes, negating the effect of atmospheric pressure
Volume of beeds = voleume of substrates in other tube
Why does anaerboic respiration produce less ATP than aerobic respiartion
Aerobic respiration invloves glycoloysis, link reaction, krebs cycle, and oxidative phosphorylation which produced 32-36 ATP
Anaerobic respiration ivloves glycolysis then fermentation, only 2 ATP is produced. Other processes cannot continue as there is no oxygen to act as the final electron acceptor
Hydrogen acceptor in anerboic respiration of mammals / yeast
Mammals - pryuvate
Yeast - ethanal
How does pyruvate enter the mitochondria
Pyruvate travels to the mitochondrial matrix by active transport
How is being able to respire anaerobically a survival advantage
When oxygen Availability is low atp can still be produced for use in active processes
Order carbohydrates, lipids and proteins in terms of their relative energy values.
Lipids carbohydrate protein
Why anaerobic respiration in animals is reversible but not in yeast
In animals - Pyruvate is converted into lactate whilst no atoms or groups are lost and the enzyme lactate dehydrogenase are still present
In yeast - pryuvate is converted into ethanal and then ethanol where co2 is lost meaning it cannot be reversed by enzyme decarboxylase
