5.2 Respiration Flashcards
What is the equation for aerobic respiration?
Glucose and oxygen —> carbon dioxide and water
Does how organisms acquire the reactants for respiration differ?
Yes
Humans and animals can inspire/expire
Fish use gills and lamella
Insects use spiracles
What are the stages of respiration?
Glycolysis
Link reaction
Krebs cycle
Electron transport chain
Where does glycolysis take place?
In the cytoplasm of the cell
Describe glycolysis?
Glucose (6 carbons) is turned into phosphorylate glucose using 2Pi from 2ATP molecules also forming 2ADP
This splits into two identical chains
From the phosphorylated glucose TP(3C) is formed via oxidation and using NAD into NADH GP(3C) is formed
Using 2ADP + 2Pi into 2ATP pyruvate(3C) is formed
Which enters the mitochondria via active transport
What are the overall products of glycolysis?
Pyruvate x2
ATP x2 (net)
NADH x2
Where does the link reaction take place?
In the matrix of the mitochondria
Describe the link reaction?
The whole reaction takes place twice in 2 identical chains
Pyruvate(3C) undergoes oxidative decarboxylation using NAD to NADH (reduction) whilst CO2 is released to form
Acetate(2C)
Acetyl coenzyme A is formed by adding CoA
What are the products of the link reaction?
Acetyl Coenzyme A x2
CO2 x2
NADH x2
Where does the Krebs cycle take place?
In the matrix of the mitochondria
What is the Krebs cycle also called?
Citric acid cycle
Describe the Krebs cycle?
A 4C acceptor molecule the acetyl coenzyme A adds acetate to the cycle (CoA goes back to the link reaction)
A 6C intermediate formed goes under oxidative decarboxylation using NAD - NADH (reduction) whilst CO2 is released
A 5C intermediate formed goes under oxidative decarboxylation using NAD - NADH (reduction) and ADP + Pi to form ATP whilst CO2 is released
A 4C intermediate uses NAD-NADH and FAD-FADH to turn back into the 4C acceptor molecule
How many Krebs cycles take place per glucose molecule?
2 Krebs cycles per 1 glucose molecule
What are the products formed in the Krebs cycle?
NADH x3 FADH x1 ATP x1 CoA x1 CO2 x2
Where does the electron transport chain take place?
In/on cristae
Describe the electron transport chain?
In the matrix NADH and FADH is oxidised to NAD and FAD giving electrons to a transmembrane protein (both also losing H+)
The electrons go through the transmembrane proteins and undergo redox reactions which releases energy used to transport H+ ions through the proteins
The H+ ion move back through a channel protein via facilitated diffusion which activates ATP synthase for ADP + Pi -> ATP
O2 is the terminal acceptor, removing H+ forming water to maintain to H+ conc gradient
What products are formed in the electron transport chain?
NAD x1
FAD x1
ATP x34
H2O (a lot)
How many ATP’s are made from 1 glucose molecule in total?
38 molecules of ATP
What can be used as alternative respiratory substrates?
Glycerol (from hydrolysed triglycerides)
A deaminated amino acid
Describe anaerobic respiration in animals?
Pyruvate + reduced NAD -> lactate + NAD
Describe anaerobic respiration in plants and microorganisms?
Pyruvate + reduced NAD -> ethanol + CO2 + NAD
Why does NAD need to be formed in anaerobic respiration?
To keep glycolysis going as 2 ATP molecules can still be produced even if the other three steps don’t work
