Respiration Flashcards
Why do we need respiration
To generate usable ATP for reactions in the body
Processes which require cellular respiration
- active transport
- endocytosis
- Exocytosis
- dna replication
- cell division
- protein synthesis
Site of aerobic respiration
Mitochondria
Mitochondria labelled
Features of mitochondria (structures in it)
Cristae
Matrix
Granules
Ribosome
Mitochondrial dna
Outer & inner (double) membrane
Four stages of aerobic respiration
Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation
Where does glycolysis occur
The cytosol (cell cytoplasm)
Overall reaction is glucose -> 2 pyruvate molecules + 2ATP + 2red.NAD: why does glucose have to be converted to pyruvate
Glucose too big to enter mitochondria, but pyruvate can
Main stages of glycolysis
1) phosphorylation of glucose to hexose biphosphate
2) splitting of hexose biphosphate into 2 T.P. Molecules
3) oxidation of TP molecules
What’s the coenzyme involved in glycolysis
NAD
What does NAD do in glycolysis
Accept H atoms from TP as it is oxidised, reducing NAD (x2)
Stage 1 of glycolysis = phosphorylation of glucose to hexose biphosphate: what happens here?
Glucose is phosphorylated by 2 ATP molecules, forming hexose biphosphate & 2 ADP as waste products
Where are the phosphate groups on hexose biphosphate
Carbon 1 & 6
Stage 3 of glycolysis: oxidation of TP molecule: what happens here?
- 2 TP molecules are oxidised to from to form 2 pyruvate molecules
- Hydrogen atom removed from each TP molecule by dehydrogenase enzymes & coenzyme NAD
- 2 NAD molecules accepts these H atoms & are reduced to from 2 reduced NAD molecules
- ADP (4 of them) molecules phosphorylated-> 4 ATP
In the link reaction, where does pyruvate from the cell cytoplasm go to?
The mitochondrial matrix
How is pyruvate moved from the cytoplasm to the mitochondrial matrix
- actively transported across double membrane of mitochondria
- using transport protein and ATP
Link reaction reactants
2 pyruvate + 2NAD + 2 CoA
Link reaction products
2CO2 + 2 reduced NAD + 2 acetyle CoA
Link reaction reactants & products equation
(This means the products of link reaction per glucose molecule btw x)
The link reaction is the only stage where (…) isn’t produced
ATP
What are the 2 stages of the link reaction
Oxidative decarboxylation & dehydrogenation of pyruvate
Formation of acetyl coenzyme A
What happens in the oxidative decarboxylation & dehydrogenation of pyruvate
How is acetyl coenzyme A formed
Where does the 3rd stage of respiration: the Kreb’s cycle: occur
In the matrix of the mitochondria
Function of the Krebs cycle
Oxidation of acetyl group from acetyl CoA to form CO2, reduced NAD & reduced FAS through the oxidation of citrate
Products of the Krebs cycle (per glucose molecule - 2 cycles)
Products of Krebs cycle per 1 cycle
3 reduced NAD
1 reduced FAD
2 carbon dioxide
1 ATP
Link reaction linked to Krebs cycle diagram
Explain the stages of the Krebs cycle using this diagram
- Acetyl group from Acetyl CoA & OOA (oxalacetate) react to form citrate
- Coenzyme A released
- Citrate oxidised to form
- 5C compound
- 1 CO2
- 1 reduced NAD - 5C compound further oxidised to form 4C intermediate compound + 1CO2 + 1 reduced NAD
- Substrate level phosphorylation occurs (ADP + phosphate group) producing 1 ATP
- A series of enzyme - catalysed redox reactions occur: to produce 1 reduced NAD, 1 reduced FAD, & OAA is regenerated so the cycle can repeat
What are the substrates that can be respired aerobically in the Kreb’s cycle
Fatty acids
Glycerol
Amino acids
Coenzymes involved in respiration? (3)
NAD
FAD
Acetyl CoA
What is acetyl CoA!
A nucleotide consisting of ribose, adenine & a vitamin
What are coenzymes
Where does the 4th stage of respiration: oxidative phosphorylation occur
Inner mitochondrial membrane
Whats the movement of protons during oxidative phosphorylation
-> matrix -> inter membrane space -> matrix
Steps of oxidative phosphorylation
What is the chemiosmosis theory
How is ATP formed as the protons re-enter the matrix
- flow of protons through proton channel in ATP synthase (located in the inner mitochondrial matrix)
- causes conformational change in ATP synthase
- this provides energy for ADP to combine with phosphate group
Products of oxidative phosphorylation (per glucose molecule)
Water & 28 ATP
Net gain of ATP per glucose per stage of respiration
Why is the theoretical yield of ATP not usually achieved
