Respiration Flashcards
What is the respiration word equation?
Glucose + oxygen —-> CO2 + H2O
What is the symbol equation for respiration?
C6H12O6 + 6O2 —-> 6CO2 + 6H2O
Why is respiration important?
All living things respire
Form ATP from the breakdown of glucose
Cells use ATP as immediate energy source
What are the two types of respiration?
Anaerobic
Aerobic
What are coenzymes?
Complex organic molecules that are used by enzymes to accept or donate molecules in a reaction
What is respiration?
A series of reactions in which energy is transferred from organic compounds, such as carbohydrates to the temporary energy store, ATP
What are the four stages of respiration?
Glycolysis
Link Reaction
Krebs cycle
Oxidative phosphorylation
Where does glycolysis happen?
Cytoplasm of mitochondria
Where does LR happen?
Matrix of mitochondria
Where does krebs happen?
Matrix of mitochondria
Where does OP happen?
Cristae of mitochondria
Describe glycolysis
Activation of glucose by phosphorylation
Splitting phosphorylated glucose into 2X TP
Oxidation of TP = H removed from each TP then H transferred to NAD+ to form rNAD
Production of ATP = enzymes convert 3C TP to 3C pyruvate
2X ATP generated from ADP (net)
Why is 2X Pi added to glucose (in activation of glucose by phosphorylation in glycolysis)?
More reactive by adding 2X Pi
Provides energy to activate glucose + lower AE needed for following enzyme controlled reaction
Where does the 2X Pi come from in glycolysis?
Hydrolysis of ATP = 2X ATP spent
What is the total yield of glycolysis?
2X ATP - small but fast (used to phosphorylate glucose)
2X rNAD
2X pyruvate
Because respiration is carried out by all living things what does it provide evidence for?
Common ancestry
What does the link reaction do?
Link glycolysis to krebs
Why does the link reaction occur twice for every glucose molecule?
For each glucose molecule in glycolysis 2X pyruvate made
LR uses 1 pyruvate molecule so krebs can happen = 2x for every glucose molecule
What is the overall equation for 1 link reaction?
Pyruvate + NAD + CoA —-> Acetyl CoA + rNAD + CO2
What happens in the link reaction?
Pyruvate (3C) decarboxylated to form CO2
Remaining 2C product (acetate) combines with coenzyme A to form acetyl CoA
Oxidation reaction occurs where NAD collects H atoms = forms rNAD
What is not produced in the link reaction?
ATP
Where does acetyl CoA go from link reaction?
Krebs
Where does CO2 go from link reaction?
Released as waste
Where does rNAD go from link reaction?
Oxidative phosphorylation
Describe the process of the krebs cycle
Acetyl CoA (from LR) joins oxaloacetate to form citrate
CoA goes back to LR to be reused
6C citrate decarboxylated + dehydrogenated
H reduces NAD
5C compound formed
Converted to 4C molecule the decarboxylated + dehydrogenated
Forms rFAD + 2X rNAD
ATP produced
4C oxaloacetate then joins with acetyl CoA
STARTS AGAIN
How much ATP is formed in krebs?
Only small amount
What is taken away from krebs by coenzymes?
Majority of its potential energy
Later converted to ATP
What does NAD + FAD do?
Carry H atoms between molecules
What are the products of krebs?
2X CO2
1X ATP
rNAD + rFAD
What is the rNAD + rFAD from krebs later used in?
Oxidative phosphorylation
Why does OP happen in the cristae of membrane?
As enzymes proteins for OP are found here
Why is there a step by step approach?
Lots of energy released in one step = lots lost as heat
If released slowly over no. of steps = more energy available for use of organism
This is why NAD + FAD transfer electrons gradually
Describe the process of oxidative phosphorylation
H atoms from glycolysis + krebs join NAD + FAD
rNAD + rFAD donate e- donate to 1st e- transport module
e- pass along ETC in a series of redox reactions
As e- pass along chain they release energy, which causes active transport of H+ across inner mitochondrial membrane into inter membrane space
H+ gather in area between mitochondrial membranes
They then diffuse back into matrix through ATP synthase channels in inner mitochondrial membrane
At the end of the chain the electrons combine with the H+ + O2 —-> H2O
O2 = final acceptor of e- in transport chain
What are the glucose alternatives in respiration?
Lipids
Proteins
Describe the respiration of process of lipids
Hydrolysed into glycerol + fatty acids Glycerol = phosphorylated Converted to TP TP ----> pyruvate Then enters LR + krebs Fatty acids = hydrolysed into 2C fragments Converted to acetyl CoA Joins krebs
Why is it useful that oxidation of lipids produce lots of H atoms?
Useful coz they produce ATP during OP
How much more energy does lipids release in respiration compared to carbohydrates?
2X more
Describe the respiration process of proteins
Hydrolysed to amino acids
Deaminated (amino acid removed)
They enter respiratory pathway at different points depending on no. of carbons
4C compounds converted to intermediate in krebs
Why is O2 important?
O2 = final acceptor
H atoms produced in glycolysis + krebs can be converted to H2O + drive ATP production
What happens without O2?
Krebs cycle + ETC can’t take place
So pyruvate builds up
Also rNAD no longer releases H
Creates backlog rNAD = no NAD regenerated
What must rNAD (produced in glycolysis) be oxidised into and why?
NAD+ so it can be reused
If NAD+ remained what would happen?
There would be no carriers to take up H atoms released during glycolysis = glycolysis would stop
What happens to make sure NAD+ doesn’t remain?
NAD+ is replenished by pyruvate
Pyruvate accepts H from rNAD
Newly oxidised NAD+ can be reused in glycolysis
What are the two types of anaerobic respiration carried out by eukaryotic cells?
Plants + microorganisms (fungi + bacteria)
Animals
What is pyruvate converted to in plant + microorganism anaerobic respiration?
Ethanol + CO2
What is pyruvate converted to in animal anaerobic respiration?
Lactate
Describe the process of anaerobic respiration in plants + microorganisms
Pyruvate decarboxylated
Forms ethanal
Ethanal reduced by H atoms supplied by rNAD
Forms ethanol
What is the equation for the process of anaerobic respiration in plants + microorganisms?
Pyruvate + NADH —-> Ethanol + CO2 + NAD+
What are the uses of anaerobic respiration in plants + microorganisms?
Yeast + brewing industry
Yeast grown anaerobically
Ferments natural carbohydrates from plant products
eg. Grapes (wine)/ barley seeds (beer)
Why does anaerobic respiration occur in animals?
To overcome temporary O2 shortage
Survival advantage
What is an example of a survival advantage of anaerobic respiration?
H2O with low O2
Immediately after birth
Describe the process of anaerobic respiration in animals
rNAD (from glycolysis) accumulates in O2 shortage
Must be removed
Pyruvate takes up 2X H from NADH = lactate (via reduction)
So NAD+ regenerated
What is the equation for the process of anaerobic respiration in animals?
Pyruvate + NADH —-> Lactate + NAD+
What happens in animals when O2 is available again, after anaerobic respiration?
Lactate oxidised to pyruvate
Pyruvate can then be further oxidised to release energy
OR converted back to glucose
What is the problem with the process following O2 being available after anaerobic respiration?
Regeneration of glucose requires lots of ATP
(Produced in aerobic respiration)
Leads to O2 debt
What is O2 debt?
Where the athlete is continuing a high level of O2 consumption
What are the problems with lactate?
Muscles cramp + fatigue
Is an acid = pH changes = affects enzyme action
Removed by blood + taken to liver where converted to glycogen
